Mark Jit
Mark Jit
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Chair and Professor of the Department of Global and Environmental Health
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Professional overview
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Mark Jit is the inaugural chair and a professor in the Department of Global and Environmental Health. He was formerly head of the Department of Infectious Disease Epidemiology & Dynamics and co-director of the Global Health Economics Centre (GHECO) at the London School of Hygiene & Tropical Medicine (LSHTM). He holds honorary appointments at LSHTM as well as the University of Hong Kong (HKU) and the National University of Singapore (NUS).
Dr. Jit’s research focuses on epidemiological and economic modeling of vaccines to support evidence-based public health decision making. He has published papers covering a range of vaccine-preventable or potentially vaccine-preventable diseases including COVID-19, measles, HPV, pneumococcus, rotavirus, influenza, Group B Streptococcus, dengue, EV71 and RSV as well as methodological papers advancing the ways vaccines are evaluated. This work has influenced many of the major changes to immunization policy in countries around the world. Dr. Jit has served on a number of expert advisory committees in the UK as well as for international organizations such as the World Health Organization. He also organises or contributes to academic and professional courses on vaccine modeling, economics and decision science around the world.
Dr. Jit received his BSc and PhD in Mathematics from University College London, specializing in mathematical biology, and a Master of Public Health degree from King’s College London.
Visit Dr. Jit's Google Scholar's page to learn more about his research portfolio.
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Education
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BSc, Mathematics, University College LondonPhD, Mathematics, University College LondonMPH, Public Health, King's College London
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Honors and awards
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Clarivate Highly Cited Researcher (20222023)Fellow of the Academy of Medical Sciences (2023)Training Fund Award, Health Protection Agency (2007)Andrew Rosen Prize, University College London (1999)Institute of Mathematics and its Applications Award (1998)Departmental Research Studentship, University College London (1998)Student Union Commendation, University College London (1997)Fillon Prize, University College London (1996)Pathfinder Award, University College London (1995)
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Publications
Publications
Meeting Report: WHO Workshop on modelling global mortality and aetiology estimates of enteric pathogens in children under five. Cape Town, 28–29th November 2018
AbstractPrudden, H. J., Hasso-Agopsowicz, M., Black, R. E., Troeger, C., Reiner, R. C., Breiman, R. F., Jit, M., Kang, G., Lamberti, L., Lanata, C. F., Lopman, B. A., Ndifon, W., Pitzer, V. E., Platts-Mills, J. A., Riddle, M. S., Smith, P. G., Hutubessy, R., & Giersing, B. (n.d.).Publication year
2020Journal title
VaccineVolume
38Issue
31Page(s)
4792-4800AbstractInvestment in vaccine product development should be guided by up-to-date and transparent global burden of disease estimates, which are also fundamental to policy recommendation and vaccine introduction decisions. For low- and middle-income countries (LMICs), vaccine prioritization is primarily driven by the number of deaths caused by different pathogens. Enteric diseases are known to be a major cause of death in LMICs. The two main modelling groups providing mortality estimates for enteric diseases are the Institute for Health Metrics and Evaluation (IHME) at the University of Washington, Seattle and the Maternal Child Epidemiology Estimation (MCEE) group, led by Johns Hopkins Bloomberg School of Public Health. Whilst previous global diarrhoea mortality estimates for under five-year-olds from these two groups were closely aligned, more recent estimates for 2016 have diverged, particularly with respect to numbers of deaths attributable to different enteric pathogens. This has impacted prioritization and investment decisions for vaccines in the development pipeline. The mission of the Product Development for Vaccines Advisory Committee (PDVAC) at the World Health Organisation (WHO) is to accelerate product development of vaccines and technologies that are urgently needed and ensure they are appropriately targeted for use in LMICs. At their 2018 meeting, PDVAC recommended the formation of an independent working group of subject matter experts to explore the reasons for the difference between the IHME and MCEE estimates, and to assess the respective strengths and limitations of the estimation approaches adopted, including a review of the data on which the estimates are based. Here, we report on the proceedings and recommendations from a consultation with the working group of experts, the IHME and MCEE modelling groups, and other key stakeholders. We briefly review the methodological approaches of both groups and provide a series of proposals for investigating the drivers for the differences in enteric disease burden estimates.Optimizing Benefits of Testing Key Workers for Infection with SARS-CoV-2: A Mathematical Modeling Analysis
AbstractSandmann, F. G., White, P. J., Ramsay, M., & Jit, M. (n.d.).Publication year
2020Journal title
Clinical Infectious DiseasesVolume
71Issue
12Page(s)
3196-3203AbstractBackground: Internationally, key workers such as healthcare staff are advised to stay at home if they or household members experience coronavirus disease 2019 (COVID-19)-like symptoms. This potentially isolates/quarantines many staff without SARS-CoV-2, while not preventing transmission from staff with asymptomatic infection. We explored the impact of testing staff on absence durations from work and transmission risks to others. Methods: We used a decision-analytic model for 1000 key workers to compare the baseline strategy of (S0) no RT-PCR testing of workers to testing workers (S1) with COVID-19-like symptoms in isolation, (S2) without COVID-19-like symptoms but in household quarantine, and (S3) all staff. We explored confirmatory re-testing scenarios of repeating all initial tests, initially positive tests, initially negative tests, or no re-testing. We varied all parameters, including the infection rate (0.1-20%), proportion asymptomatic (10-80%), sensitivity (60-95%), and specificity (90-100%). Results: Testing all staff (S3) changes the risk of workplace transmission by-56.9 to +1.0 workers/1000 tests (with reductions throughout at RT-PCR sensitivity ≥65%), and absences by-0.5 to +3.6 days/test but at heightened testing needs of 989.6-1995.9 tests/1000 workers. Testing workers in household quarantine (S2) reduces absences the most by 3.0-6.9 days/test (at 47.0-210.4 tests/1000 workers), while increasing risk of workplace transmission by 0.02-49.5 infected workers/1000 tests (which can be minimized when re-testing initially negative tests). Conclusions: Based on optimizing absence durations or transmission risk, our modeling suggests testing staff in household quarantine or all staff, depending on infection levels and testing capacities.Quantifying the economic cost of antibiotic resistance and the impact of related interventions: Rapid methodological review, conceptual framework and recommendations for future studies
AbstractJit, M., Ng, D. H. L., Luangasanatip, N., Sandmann, F., Atkins, K. E., Robotham, J. V., & Pouwels, K. B. (n.d.).Publication year
2020Journal title
BMC MedicineVolume
18Issue
1AbstractBackground: Antibiotic resistance (ABR) poses a major threat to health and economic wellbeing worldwide. Reducing ABR will require government interventions to incentivise antibiotic development, prudent antibiotic use, infection control and deployment of partial substitutes such as rapid diagnostics and vaccines. The scale of such interventions needs to be calibrated to accurate and comprehensive estimates of the economic cost of ABR. Methods: A conceptual framework for estimating costs attributable to ABR was developed based on previous literature highlighting methodological shortcomings in the field and additional deductive epidemiological and economic reasoning. The framework was supplemented by a rapid methodological review. Results: The review identified 110 articles quantifying ABR costs. Most were based in high-income countries only (91/110), set in hospitals (95/110), used a healthcare provider or payer perspective (97/110), and used matched cohort approaches to compare costs of patients with antibiotic-resistant infections and antibiotic-susceptible infections (or no infection) (87/110). Better use of methods to correct biases and confounding when making this comparison is needed. Findings also need to be extended beyond their limitations in (1) time (projecting present costs into the future), (2) perspective (from the healthcare sector to entire societies and economies), (3) scope (from individuals to communities and ecosystems), and (4) space (from single sites to countries and the world). Analyses of the impact of interventions need to be extended to examine the impact of the intervention on ABR, rather than considering ABR as an exogeneous factor. Conclusions: Quantifying the economic cost of resistance will require greater rigour and innovation in the use of existing methods to design studies that accurately collect relevant outcomes and further research into new techniques for capturing broader economic outcomes.Quantifying the impact of physical distance measures on the transmission of COVID-19 in the UK
AbstractJarvis, C. I., Van Zandvoort, K., Gimma, A., Prem, K., Auzenbergs, M., O’Reilly, K., Medley, G., Emery, J. C., Houben, R. M., Davies, N., Nightingale, E. S., Flasche, S., Jombart, T., Hellewell, J., Abbott, S., Munday, J. D., Bosse, N. I., Funk, S., Sun, F., … Edmunds, W. J. (n.d.).Publication year
2020Journal title
BMC MedicineVolume
18Issue
1AbstractBackground: To mitigate and slow the spread of COVID-19, many countries have adopted unprecedented physical distancing policies, including the UK. We evaluate whether these measures might be sufficient to control the epidemic by estimating their impact on the reproduction number (R 0, the average number of secondary cases generated per case). Methods: We asked a representative sample of UK adults about their contact patterns on the previous day. The questionnaire was conducted online via email recruitment and documents the age and location of contacts and a measure of their intimacy (whether physical contact was made or not). In addition, we asked about adherence to different physical distancing measures. The first surveys were sent on Tuesday, 24 March, 1 day after a "lockdown" was implemented across the UK. We compared measured contact patterns during the "lockdown" to patterns of social contact made during a non-epidemic period. By comparing these, we estimated the change in reproduction number as a consequence of the physical distancing measures imposed. We used a meta-analysis of published estimates to inform our estimates of the reproduction number before interventions were put in place. Results: We found a 74% reduction in the average daily number of contacts observed per participant (from 10.8 to 2.8). This would be sufficient to reduce R 0 from 2.6 prior to lockdown to 0.62 (95% confidence interval [CI] 0.37-0.89) after the lockdown, based on all types of contact and 0.37 (95% CI = 0.22-0.53) for physical (skin to skin) contacts only. Conclusions: The physical distancing measures adopted by the UK public have substantially reduced contact levels and will likely lead to a substantial impact and a decline in cases in the coming weeks. However, this projected decline in incidence will not occur immediately as there are significant delays between infection, the onset of symptomatic disease, and hospitalisation, as well as further delays to these events being reported. Tracking behavioural change can give a more rapid assessment of the impact of physical distancing measures than routine epidemiological surveillance.Reconstructing the early global dynamics of under-ascertained COVID-19 cases and infections
Failed generating bibliography.AbstractPublication year
2020Journal title
BMC MedicineVolume
18Issue
1AbstractBackground: Asymptomatic or subclinical SARS-CoV-2 infections are often unreported, which means that confirmed case counts may not accurately reflect underlying epidemic dynamics. Understanding the level of ascertainment (the ratio of confirmed symptomatic cases to the true number of symptomatic individuals) and undetected epidemic progression is crucial to informing COVID-19 response planning, including the introduction and relaxation of control measures. Estimating case ascertainment over time allows for accurate estimates of specific outcomes such as seroprevalence, which is essential for planning control measures. Methods: Using reported data on COVID-19 cases and fatalities globally, we estimated the proportion of symptomatic cases (i.e. any person with any of fever ≥ 37.5 °C, cough, shortness of breath, sudden onset of anosmia, ageusia or dysgeusia illness) that were reported in 210 countries and territories, given those countries had experienced more than ten deaths. We used published estimates of the baseline case fatality ratio (CFR), which was adjusted for delays and under-ascertainment, then calculated the ratio of this baseline CFR to an estimated local delay-adjusted CFR to estimate the level of under-ascertainment in a particular location. We then fit a Bayesian Gaussian process model to estimate the temporal pattern of under-ascertainment. Results: Based on reported cases and deaths, we estimated that, during March 2020, the median percentage of symptomatic cases detected across the 84 countries which experienced more than ten deaths ranged from 2.4% (Bangladesh) to 100% (Chile). Across the ten countries with the highest number of total confirmed cases as of 6 July 2020, we estimated that the peak number of symptomatic cases ranged from 1.4 times (Chile) to 18 times (France) larger than reported. Comparing our model with national and regional seroprevalence data where available, we find that our estimates are consistent with observed values. Finally, we estimated seroprevalence for each country. As of 7 June, our seroprevalence estimates range from 0% (many countries) to 13% (95% CrI 5.6–24%) (Belgium). Conclusions: We found substantial under-ascertainment of symptomatic cases, particularly at the peak of the first wave of the SARS-CoV-2 pandemic, in many countries. Reported case counts will therefore likely underestimate the rate of outbreak growth initially and underestimate the decline in the later stages of an epidemic. Although there was considerable under-reporting in many locations, our estimates were consistent with emerging serological data, suggesting that the proportion of each country’s population infected with SARS-CoV-2 worldwide is generally low.Response strategies for COVID-19 epidemics in African settings: a mathematical modelling study
Failed generating bibliography.AbstractPublication year
2020Journal title
BMC MedicineVolume
18Issue
1AbstractBackground: The health impact of COVID-19 may differ in African settings as compared to countries in Europe or China due to demographic, epidemiological, environmental and socio-economic factors. We evaluated strategies to reduce SARS-CoV-2 burden in African countries, so as to support decisions that balance minimising mortality, protecting health services and safeguarding livelihoods. Methods: We used a Susceptible-Exposed-Infectious-Recovered mathematical model, stratified by age, to predict the evolution of COVID-19 epidemics in three countries representing a range of age distributions in Africa (from oldest to youngest average age: Mauritius, Nigeria and Niger), under various effectiveness assumptions for combinations of different non-pharmaceutical interventions: self-isolation of symptomatic people, physical distancing and ‘shielding’ (physical isolation) of the high-risk population. We adapted model parameters to better represent uncertainty about what might be expected in African populations, in particular by shifting the distribution of severity risk towards younger ages and increasing the case-fatality ratio. We also present sensitivity analyses for key model parameters subject to uncertainty. Results: We predicted median symptomatic attack rates over the first 12 months of 23% (Niger) to 42% (Mauritius), peaking at 2–4 months, if epidemics were unmitigated. Self-isolation while symptomatic had a maximum impact of about 30% on reducing severe cases, while the impact of physical distancing varied widely depending on percent contact reduction and R0. The effect of shielding high-risk people, e.g. by rehousing them in physical isolation, was sensitive mainly to residual contact with low-risk people, and to a lesser extent to contact among shielded individuals. Mitigation strategies incorporating self-isolation of symptomatic individuals, moderate physical distancing and high uptake of shielding reduced predicted peak bed demand and mortality by around 50%. Lockdowns delayed epidemics by about 3 months. Estimates were sensitive to differences in age-specific social mixing patterns, as published in the literature, and assumptions on transmissibility, infectiousness of asymptomatic cases and risk of severe disease or death by age. Conclusions: In African settings, as elsewhere, current evidence suggests large COVID-19 epidemics are expected. However, African countries have fewer means to suppress transmission and manage cases. We found that self-isolation of symptomatic persons and general physical distancing are unlikely to avert very large epidemics, unless distancing takes the form of stringent lockdown measures. However, both interventions help to mitigate the epidemic. Shielding of high-risk individuals can reduce health service demand and, even more markedly, mortality if it features high uptake and low contact of shielded and unshielded people, with no increase in contact among shielded people. Strategies combining self-isolation, moderate physical distancing and shielding could achieve substantial reductions in mortality in African countries. Temporary lockdowns, where socioeconomically acceptable, can help gain crucial time for planning and expanding health service capacity.Routine childhood immunisation during the COVID-19 pandemic in Africa: a benefit–risk analysis of health benefits versus excess risk of SARS-CoV-2 infection
Failed generating bibliography.AbstractPublication year
2020Journal title
The Lancet Global HealthVolume
8Issue
10Page(s)
e1264-e1272AbstractBackground: National immunisation programmes globally are at risk of suspension due to the severe health system constraints and physical distancing measures in place to mitigate the ongoing COVID-19 pandemic. We aimed to compare the health benefits of sustaining routine childhood immunisation in Africa with the risk of acquiring severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection through visiting routine vaccination service delivery points. Methods: We considered a high-impact scenario and a low-impact scenario to approximate the child deaths that could be caused by immunisation coverage reductions during COVID-19 outbreaks. In the high-impact scenario, we used previously reported country-specific child mortality impact estimates of childhood immunisation for diphtheria, tetanus, pertussis, hepatitis B, Haemophilus influenzae type b, Streptococcus pneumoniae, rotavirus, measles, meningitis A, rubella, and yellow fever to approximate the future deaths averted before 5 years of age by routine childhood vaccination during a 6-month COVID-19 risk period without catch-up campaigns. In the low-impact scenario, we approximated the health benefits of sustaining routine childhood immunisation on only the child deaths averted from measles outbreaks during the COVID-19 risk period. We assumed that contact-reducing interventions flattened the outbreak curve during the COVID-19 risk period, that 60% of the population will have been infected by the end of that period, that children can be infected by either vaccinators or during transport, and that upon child infection the whole household will be infected. Country-specific household age structure estimates and age-dependent infection-fatality rates were applied to calculate the number of deaths attributable to the vaccination clinic visits. We present benefit–risk ratios for routine childhood immunisation, with 95% uncertainty intervals (UIs) from a probabilistic sensitivity analysis. Findings: In the high-impact scenario, for every one excess COVID-19 death attributable to SARS-CoV-2 infections acquired during routine vaccination clinic visits, 84 (95% UI 14–267) deaths in children could be prevented by sustaining routine childhood immunisation in Africa. The benefit–risk ratio for the vaccinated children is 85 000 (4900–546 000), for their siblings (<20 years) is 75 000 (4400–483 000), for their parents or adult carers (aged 20–60 years) is 769 (148–2700), and for older adults (>60 years) is 96 (14–307). In the low-impact scenario that approximates the health benefits to only the child deaths averted from measles outbreaks, the benefit–risk ratio to the households of vaccinated children is 3 (0–10); if the risk to only the vaccinated children is considered, the benefit–risk ratio is 3000 (182–21 000). Interpretation: The deaths prevented by sustaining routine childhood immunisation in Africa outweigh the excess risk of COVID-19 deaths associated with vaccination clinic visits, especially for the vaccinated children. Routine childhood immunisation should be sustained in Africa as much as possible, while considering other factors such as logistical constraints, staff shortages, and reallocation of resources during the COVID-19 pandemic. Funding: Gavi, the Vaccine Alliance; Bill & Melinda Gates Foundation.Shaping meeting to explore the value of a coordinated work plan for epidemic and pandemic influenza vaccine preparedness
Failed generating bibliography.AbstractPublication year
2020Journal title
VaccineVolume
38Issue
16Page(s)
3179-3183AbstractIn March 2019, a group of global health leaders with expertise in influenza, vaccinology and pandemic preparedness was convened for a meeting titled “Shaping Meeting to explore the value of a coordinated work plan for epidemic and pandemic influenza vaccine preparedness.” Influenza epidemics occur annually in every country in the world, resulting in significant global burden of illness and deaths. While every country is effected, most deaths and severe disease occur in low- and lower middle-income countries (LIC and LMIC). Influenza immunization programs that limit the burden of disease, deaths, and reduce economic impact are a fundamental public health intervention for seasonal epidemics. In addition, they provide the experience, systems and infrastructure for the timely and efficient use of vaccines and other medical countermeasures critical for effective pandemic responses. Pandemic influenza response activities, including vaccination efforts, will be most effective if used and practiced regularly. Consequently, countries with seasonal influenza prevention and control programs should be better prepared for, and have more effective pandemic responses than countries without such programs. A decade after the 2009 pandemic, despite ongoing prevention efforts, most LICs and LMICs still lack access to robust seasonal influenza immunization programs. Given this current state, meeting participants concluded that there is critical need to advance the expansion and strengthening of seasonal influenza immunization programs in LICs and LMICs not only to reduce the economic and public health effects of annual influenza epidemics, but also to increase preparedness to mitigate the threat of future pandemics and improve global heath security. Many government and private sectors, in a whole of government approach, need to be working together to support and advance countries' epidemic and pandemic influenza capacities preparedness objectives. Accomplishment of these objectives can be achieved with a coordinated work plan developed and guided by an alliance of international stakeholders, to include, among others, government, and nongovernment organization representation, civil society representatives, vaccine manufacturers, international organizations, and health security and influenza experts.Systematic Review on the Acute Cost-of-illness of Sepsis and Meningitis in Neonates and Infants
AbstractSalman, O., Procter, S. R., McGregor, C., Paul, P., Hutubessy, R., Lawn, J. E., & Jit, M. (n.d.).Publication year
2020Journal title
Pediatric Infectious Disease JournalVolume
39Issue
1Page(s)
35-40AbstractBackground: Sepsis and meningitis in neonates and infants are a source of substantial morbidity, mortality and economic loss. The objective of this review is to estimate the acute costs associated with treating sepsis, meningitis and meningococcal septicemia, in neonates and infants, worldwide. Methods: The electronic databases Medline, Embase and EconLit were searched and exported on November 24, 2018. Studies that reported an average hospitalization cost for confirmed cases of sepsis, meningitis or meningococcal septicemia were eligible for our review. Descriptive data were extracted and reported costs were inflated and converted. A narrative synthesis of the costs was conducted. Results: Our review identified 20 studies reporting costs of sepsis, meningitis and/or meningococcal septicemia. Costs ranged from $55 to $129,632 for sepsis and from $222 to $33,635 for meningitis (in 2017 US dollars). One study estimated the cost of meningococcal septicemia to be $56,286. All reported costs were estimated from the perspective of the healthcare provider or payer. Most studies were from the United States, which also had the highest costs. Only a few studies were identified for low- and middle-income countries, which reported lower costs than high-income countries for both sepsis and meningitis. Conclusions: Sepsis and meningitis in neonates and infants are associated with substantial costs to the healthcare system and showed a marked difference across global income groups. However, more research is needed to inform costs in low- and middle-income settings and to understand the economic costs borne by families and wider society.The contribution of asymptomatic sars-cov-2 infections to transmission on the diamond princess cruise ship
Failed generating bibliography.AbstractPublication year
2020Journal title
eLifeVolume
9Page(s)
1-68AbstractA key unknown for SARS-CoV-2 is how asymptomatic infections contribute to transmission. We used a transmission model with asymptomatic and presymptomatic states, calibrated to data on disease onset and test frequency from the Diamond Princess cruise ship outbreak, to quantify the contribution of asymptomatic infections to transmission. The model estimated that 74% (70-78%, 95% posterior interval) of infections proceeded asymptomatically. Despite intense testing, 53% (51-56%) of infections remained undetected, most of them asymptomatic. Asymptomatic individuals were the source for 69% (20-85%) of all infections. The data did not allow identification of the infectiousness of asymptomatic infections, however low ranges (0-25%) required a net reproduction number for individuals progressing through presymptomatic and symptomatic stages of at least 15. Asymptomatic SARS-CoV-2 infections may contribute substantially to transmission. Control measures, and models projecting their potential impact, need to look beyond the symptomatic cases if they are to understand and address ongoing transmission.The contribution of pre-symptomatic infection to the transmission dynamics of COVID-2019
Failed generating bibliography.AbstractPublication year
2020Journal title
Wellcome Open ResearchVolume
5AbstractBackground: Pre-symptomatic transmission can be a key determinant of the effectiveness of containment and mitigation strategies for infectious diseases, particularly if interventions rely on syndromic case finding. For COVID-19, infections in the absence of apparent symptoms have been reported frequently alongside circumstantial evidence for asymptomatic or pre-symptomatic transmission. We estimated the potential contribution of pre-symptomatic cases to COVID-19 transmission. Methods: Using the probability for symptom onset on a given day inferred from the incubation period, we attributed the serial interval reported from Shenzen, China, into likely pre-symptomatic and symptomatic transmission. We used the serial interval derived for cases isolated more than 6 days after symptom onset as the no active case finding scenario and the unrestricted serial interval as the active case finding scenario. We reported the estimate assuming no correlation between the incubation period and the serial interval alongside a range indicating alternative assumptions of positive and negative correlation. Results: We estimated that 23% (range accounting for correlation: 12 - 28%) of transmissions in Shenzen may have originated from pre-symptomatic infections. Through accelerated case isolation following symptom onset, this percentage increased to 46% (21 - 46%), implying that about 35% of secondary infections among symptomatic cases have been prevented. These results were robust to using reported incubation periods and serial intervals from other settings. Conclusions: Pre-symptomatic transmission may be essential to consider for containment and mitigation strategies for COVID-19.The effect of control strategies to reduce social mixing on outcomes of the COVID-19 epidemic in Wuhan, China: a modelling study
Failed generating bibliography.AbstractPublication year
2020Journal title
The Lancet Public HealthVolume
5Issue
5Page(s)
e261-e270AbstractBackground: In December, 2019, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a novel coronavirus, emerged in Wuhan, China. Since then, the city of Wuhan has taken unprecedented measures in response to the outbreak, including extended school and workplace closures. We aimed to estimate the effects of physical distancing measures on the progression of the COVID-19 epidemic, hoping to provide some insights for the rest of the world. Methods: To examine how changes in population mixing have affected outbreak progression in Wuhan, we used synthetic location-specific contact patterns in Wuhan and adapted these in the presence of school closures, extended workplace closures, and a reduction in mixing in the general community. Using these matrices and the latest estimates of the epidemiological parameters of the Wuhan outbreak, we simulated the ongoing trajectory of an outbreak in Wuhan using an age-structured susceptible-exposed-infected-removed (SEIR) model for several physical distancing measures. We fitted the latest estimates of epidemic parameters from a transmission model to data on local and internationally exported cases from Wuhan in an age-structured epidemic framework and investigated the age distribution of cases. We also simulated lifting of the control measures by allowing people to return to work in a phased-in way and looked at the effects of returning to work at different stages of the underlying outbreak (at the beginning of March or April). Findings: Our projections show that physical distancing measures were most effective if the staggered return to work was at the beginning of April; this reduced the median number of infections by more than 92% (IQR 66–97) and 24% (13–90) in mid-2020 and end-2020, respectively. There are benefits to sustaining these measures until April in terms of delaying and reducing the height of the peak, median epidemic size at end-2020, and affording health-care systems more time to expand and respond. However, the modelled effects of physical distancing measures vary by the duration of infectiousness and the role school children have in the epidemic. Interpretation: Restrictions on activities in Wuhan, if maintained until April, would probably help to delay the epidemic peak. Our projections suggest that premature and sudden lifting of interventions could lead to an earlier secondary peak, which could be flattened by relaxing the interventions gradually. However, there are limitations to our analysis, including large uncertainties around estimates of R0 and the duration of infectiousness. Funding: Bill & Melinda Gates Foundation, National Institute for Health Research, Wellcome Trust, and Health Data Research UK.The effect of time since measles vaccination and age at first dose on measles vaccine effectiveness – A systematic review
AbstractHughes, S. L., Bolotin, S., Khan, S., Li, Y., Johnson, C., Friedman, L., Tricco, A. C., Hahné, S. J., Heffernan, J. M., Dabbagh, A., Durrheim, D. N., Orenstein, W. A., Moss, W. J., Jit, M., & Crowcroft, N. S. (n.d.).Publication year
2020Journal title
VaccineVolume
38Issue
3Page(s)
460-469AbstractBackground: In settings where measles has been eliminated, vaccine-derived immunity may in theory wane more rapidly due to a lack of immune boosting by circulating measles virus. We aimed to assess whether measles vaccine effectiveness (VE) waned over time, and if so, whether differentially in measles-eliminated and measles-endemic settings. Methods: We performed a systematic literature review of studies that reported VE and time since vaccination with measles-containing vaccine (MCV). We extracted information on case definition (clinical symptoms and/or laboratory diagnosis), method of vaccination status ascertainment (medical record or vaccine registry), as well as any biases which may have arisen from cold chain issues and a lack of an age at first dose of MCV. We then used linear regression to evaluate VE as a function of age at first dose of MCV and time since MCV. Results: After screening 14,782 citations, we identified three full-text articles from measles-eliminated settings and 33 articles from measles-endemic settings. In elimination settings, two-dose VE estimates increased as age at first dose of MCV increased and decreased as time since MCV increased; however, the small number of studies available limited interpretation. In measles-endemic settings, one-dose VE increased by 1.5% (95% CI 0.5, 2.5) for every month increase in age at first dose of MCV. We found no evidence of waning VE in endemic settings. Conclusions: The paucity of data from measles-eliminated settings indicates that additional studies and approaches (such as studies using proxies including laboratory correlates of protection) are needed to answer the question of whether VE in measles-eliminated settings wanes. Age at first dose of MCV was the most important factor in determining VE. More VE studies need to be conducted in elimination settings, and standards should be developed for information collected and reported in such studies.The effect of travel restrictions on the geographical spread of COVID-19 between large cities in China: A modelling study
AbstractQuilty, B. J., Diamond, C., Liu, Y., Gibbs, H., Russell, T. W., Jarvis, C. I., Prem, K., Pearson, C. A., Clifford, S., Flasche, S., Emery, J. C., Auzenbergs, M., Davies, N., Nightingale, E. S., Van Zandvoort, K., Jombart, T., Deol, A. K., Edmunds, W. J., Hellewell, J., … Jit, M. (n.d.).Publication year
2020Journal title
BMC MedicineVolume
18Issue
1AbstractBackground: To contain the spread of COVID-19, a cordon sanitaire was put in place in Wuhan prior to the Lunar New Year, on 23 January 2020. We assess the efficacy of the cordon sanitaire to delay the introduction and onset of local transmission of COVID-19 in other major cities in mainland China. Methods: We estimated the number of infected travellers from Wuhan to other major cities in mainland China from November 2019 to February 2020 using previously estimated COVID-19 prevalence in Wuhan and publicly available mobility data. We focused on Beijing, Chongqing, Hangzhou, and Shenzhen as four representative major cities to identify the potential independent contribution of the cordon sanitaire and holiday travel. To do this, we simulated outbreaks generated by infected arrivals in these destination cities using stochastic branching processes. We also modelled the effect of the cordon sanitaire in combination with reduced transmissibility scenarios to simulate the effect of local non-pharmaceutical interventions. Results: We find that in the four cities, given the potentially high prevalence of COVID-19 in Wuhan between December 2019 and early January 2020, local transmission may have been seeded as early as 1-8 January 2020. By the time the cordon sanitaire was imposed, infections were likely in the thousands. The cordon sanitaire alone did not substantially affect the epidemic progression in these cities, although it may have had some effect in smaller cities. Reduced transmissibility resulted in a notable decrease in the incidence of infection in the four studied cities. Conclusions: Our results indicate that sustained transmission was likely occurring several weeks prior to the implementation of the cordon sanitaire in four major cities of mainland China and that the observed decrease in incidence was likely attributable to other non-pharmaceutical, transmission-reducing interventions.The impact of maternal RSV vaccine to protect infants in Gavi-supported countries: Estimates from two models
AbstractBaral, R., Li, X., Willem, L., Antillon, M., Vilajeliu, A., Jit, M., Beutels, P., & Pecenka, C. (n.d.).Publication year
2020Journal title
VaccineVolume
38Issue
33Page(s)
5139-5147AbstractBackground: Interventions to protect young infants against respiratory syncytial virus (RSV) are in advanced phases of development and are expected to be available in the foreseeable future. Gavi, the Vaccine Alliance, included maternal vaccines and infant monoclonal antibodies for RSV as part of the 2018 vaccine investment strategy (VIS) and decided to support these products subject to licensure, World Health Organization prequalification, Strategic Advisory Group of Experts recommendation, and meeting the financial assumptions used as the basis of the investment case. Impact estimates reported in this manuscript were used to inform the Gavi VIS. Methods: We compared two independent vaccine impact models to evaluate a potential maternal RSV vaccine's impact on infant health in 73 Gavi-supported countries. Key inputs were harmonized across both models. We analyzed various scenarios to evaluate the effect of uncertain model parameters such as vaccine efficacy, duration of infant protection, and infant disease burden. Estimates of averted cases, severe cases, hospitalizations, deaths, and disability-adjusted life years (DALYs) were calculated over the 2023–2035 horizon. Findings: A maternal RSV vaccine with 60% efficacy offering 5 months of infant protection implemented across 73 low- and middle-income countries could avert 10.1–12.5 million cases, 2.8–4.0 million hospitalizations, 123.7–177.7 thousand deaths, and 8.5–11.9 million DALYs among infants under 6 months of age for the duration of analysis (2023–2035). Maternal RSV vaccination was projected to avert up to 42% of estimated RSV deaths among infants under 6 months in year 2035. Alternative scenario analyses with higher disease burden assumptions showed that a maternal vaccine could avert as many as 325–355 thousand deaths among infants under 6 months. Interpretation: RSV maternal immunization is projected to substantially reduce mortality and morbidity among young infants if introduced across Gavi-supported countries. Funding: This work was supported by Bill & Melinda Gates Foundation, Seattle, WA, and Respiratory Syncytial Virus Consortium in Europe. The findings and conclusions contained within are those of the authors and do not necessarily reflect positions or policies of the Bill & Melinda Gates Foundation or of the Respiratory Syncytial Virus Consortium. LW is supported by Research Foundation–Flanders (1234620 N).The impact of vaccination on gender equity: Conceptual framework and human papillomavirus (HPV) vaccine case study
AbstractPortnoy, A., Clark, S., Ozawa, S., & Jit, M. (n.d.).Publication year
2020Journal title
International Journal for Equity in HealthVolume
19Issue
1AbstractBackground: Although the beneficial effects of vaccines on equity by socioeconomic status and geography are increasingly well-documented, little has been done to extend these analyses to examine the linkage between vaccination and gender equity. In this paper, evidence from the published literature is used to develop a conceptual framework demonstrating the potential impact of vaccination on measures of gender equity. This framework is then applied to human papillomavirus (HPV) vaccination in three countries with different economic and disease burden profiles to establish a proof of concept in a variety of contexts. Methods: We conducted a literature review examining evidence on the linkage between health outcomes and dimensions of gender equity. We utilized the Papillomavirus Rapid Interface for Modelling and Economics (PRIME) model to estimate cervical cancer incidence and deaths due to HPV types 16/18 by age in each country. We estimated labor force participation and fertility effects from improvements in health, and converted these into inputs consistent with those used to calculate the United Nations Gender Inequality Index to assess gender equity. Results: In our case study, we found that HPV vaccination among girls could help narrow socioeconomic gender disparities by quantifying the main pathways by which HPV vaccination improves health, which enables improvement in gender equity indicators such as labor force participation and maternal mortality ratios. While these improvements are small when averaged over the entire population, the components measured - labor force participation and maternal mortality ratio - account for 50% of the index scores. Conclusions: This proof of concept model is a starting point to inform future health and economic analyses that might incorporate the impact of gender equity as an additional impact of vaccination in improving the health and well-being of the population.The role of vaccines in combating antimicrobial resistance
Jit, M., & Cooper, B. (n.d.). In Challenges to Tackling Antimicrobial Resistance (1–).Publication year
2020Page(s)
181-206Using a real-world network to model localized COVID-19 control strategies
Failed generating bibliography.AbstractPublication year
2020Journal title
Nature MedicineVolume
26Issue
10Page(s)
1616-1622AbstractCase isolation and contact tracing can contribute to the control of COVID-19 outbreaks1,2. However, it remains unclear how real-world social networks could influence the effectiveness and efficiency of such approaches. To address this issue, we simulated control strategies for SARS-CoV-2 transmission in a real-world social network generated from high-resolution GPS data that were gathered in the course of a citizen-science experiment3,4. We found that tracing the contacts of contacts reduced the size of simulated outbreaks more than tracing of only contacts, but this strategy also resulted in almost half of the local population being quarantined at a single point in time. Testing and releasing non-infectious individuals from quarantine led to increases in outbreak size, suggesting that contact tracing and quarantine might be most effective as a ‘local lockdown’ strategy when contact rates are high. Finally, we estimated that combining physical distancing with contact tracing could enable epidemic control while reducing the number of quarantined individuals. Our findings suggest that targeted tracing and quarantine strategies would be most efficient when combined with other control measures such as physical distancing.A Scoping Review of Investment Cases for Vaccines and Immunization Programs
AbstractSim, S. Y., Jit, M., Constenla, D., Peters, D. H., & Hutubessy, R. C. (n.d.).Publication year
2019Journal title
Value in HealthVolume
22Issue
8Page(s)
942-952AbstractBackground: Many investment cases have recently been published intending to show the value of new health investments, but without consistent methodological approaches. Objectives: To conduct a scoping review of existing investment cases (using vaccines and immunization programs as an example), identify common characteristics that define these investment cases, and examine their role within the broader context of the vaccine development and introduction. Methods: A systematic search was conducted from January 1980 to November 2017 to identify investment cases in the area of vaccines and immunization programs from gray literature and electronic bibliographic databases. Investment case outcomes, objectives, key variables, target audiences, and funding sources were extracted and analyzed according to their reporting frequency. Results: We found 24 investment cases, and most of them aim to provide information for decisions (12 cases) or advocate for a specific agenda (9 cases). Outcomes presented fell into 4 broad categories—burden of disease, cost of investment, impact of investment, and other considerations for implementation. Number of deaths averted (70%), incremental cost-effectiveness ratios (67%), and reduction in health and socioeconomic inequalities (54%) were the most frequently reported outcome measures for impact of investment. Health system capacity (79%) and vaccine financing landscape (75%) were the most common considerations for implementation. A sizable proportion (41.4%) of investment cases did not reveal their funding sources. Conclusions: This review describes information that is critical to decision making about resource mobilization and allocation concerning vaccines. Global efforts to harmonize investment cases more broadly will increase transparency and comparability.Adjusting for Inflation and Currency Changes Within Health Economic Studies
AbstractTurner, H. C., Lauer, J. A., Tran, B. X., Teerawattananon, Y., & Jit, M. (n.d.).Publication year
2019Journal title
Value in HealthVolume
22Issue
9Page(s)
1026-1032AbstractObjectives: Within health economic studies, it is often necessary to adjust costs obtained from different time periods for inflation. Nevertheless, many studies do not report the methods used for this in sufficient detail. In this article, we outline the principal methods used to adjust for inflation, with a focus on studies relating to healthcare interventions in low- and middle-income countries. We also discuss issues relating to converting local currencies to international dollars and US$ and adjusting cost data collected from other countries or previous studies. Methods: We outlined the 3 main methods used to adjust for inflation for studies in these settings: exchanging the local currency to US$ or international dollars and then inflating using US inflation rates (method 1); inflating the local currency using local inflation rates and then exchanging to US$ or international dollars (method 2); splitting the costs into tradable and nontradable resources and using method 1 on the tradable resources and method 2 on the nontradable resources (method 3). Results: In a hypothetical example of adjusting a cost of US$100 incurred in Vietnam from 2006 to 2016 prices, the adjusted cost from the 3 methods were US$116.84, US$172.09, and US$161.04, respectively. Conclusions: The different methods for adjusting for inflation can yield substantially different results. We make recommendations regarding the most appropriate method for various scenarios. Moving forward, it is vital that studies report the methodology they use to adjust for inflation more transparently.Antimicrobial Resistance in the Asia Pacific region: A meeting report
AbstractYam, E. L. Y., Hsu, L. Y., Yap, E. P. H., Yeo, T. W., Lee, V., Schlundt, J., Lwin, M. O., Limmathurotsakul, D., Jit, M., Dedon, P., Turner, P., & Wilder-Smith, A. (n.d.).Publication year
2019Journal title
Antimicrobial Resistance and Infection ControlVolume
8Issue
1AbstractThe Asia Pacific region, home to two-thirds of the world's population and ten of the least developed countries, is considered a regional hot-spot for the emergence and spread of antimicrobial resistance (AMR). Despite this, there is a dearth of high-quality regional data on the extent of AMR. Recognising the urgency to close this gap, Singapore organised a meeting to discuss the problems in the region and frame a call for action. Representatives from across the region and beyond attended the meeting on the "Antimicrobial Resistance in the Asia Pacific & its impact on Singapore" held in November 2018. This meeting report is a summary of the discussions on the challenges and progress in surveillance, drivers and levers of AMR emergence, and the promising innovations and technologies that could be used to combat the increasing threat of AMR in the region. Enhanced surveillance and research to provide improved evidence-based strategies and policies are needed. The major themes that emerged for an action plan are working towards a tailored solution for the region by harnessing the One Health approach, enhancing inter-country collaborations, and collaboratively leverage upon new emerging technologies. A regionally coordinated effort that is target-driven, sustainable and builds on a framework facilitating communication and governance will strengthen the fight against AMR in the Asia Pacific region.Clinical impact and cost-effectiveness of primary cytology versus human papillomavirus testing for cervical cancer screening in England
AbstractBains, I., Choi, Y. H., Soldan, K., & Jit, M. (n.d.).Publication year
2019Journal title
International Journal of Gynecological CancerVolume
29Issue
4Page(s)
669-675AbstractObjectives In England, human papillomavirus (HPV) testing is to replace cytological screening by 2019-2020. We conducted a model-based economic evaluation to project the long-term clinical impact and cost-effectiveness of routine cytology versus HPV testing. Methods An individual-based model of HPV acquisition, natural history, and cervical cancer screening was used to compare cytological screening and HPV testing with cytology triage for women aged 25-64 years (with either 3- or 5-year screening intervals for women aged under 50 years). The model was fitted to data from England's National Health Service Cervical Screening Programme. Both clinical and economic outcomes were projected to inform cost-effectiveness analyses. Results HPV testing is likely to decrease annual cytology testing (by 2.76 million), cervical cancer incidence (by 290 cases), and health system costs (by £13 million). It may increase the number of colposcopies, although this could be reduced without leading to more cancers compared with primary cytology by increasing the interval between screens to 5 years. The impact in terms of quality-adjusted life-years (QALYs) depends on the quality of life weight given to colposcopies versus cancer. Conclusions England's move from cytology to HPV screening may potentially be life-saving and cost-effective. Cost-effectiveness can be improved further by extending the interval between screens or using alternative triage methods such as partial or full genotyping.Combining serological and contact data to derive target immunity levels for achieving and maintaining measles elimination
AbstractFunk, S., Knapp, J. K., Lebo, E., Reef, S. E., Dabbagh, A. J., Kretsinger, K., Jit, M., Edmunds, W. J., & Strebel, P. M. (n.d.).Publication year
2019Journal title
BMC MedicineVolume
17Issue
1AbstractBackground: Vaccination has reduced the global incidence of measles to the lowest rates in history. However, local interruption of measles virus transmission requires sustained high levels of population immunity that can be challenging to achieve and maintain. The herd immunity threshold for measles is typically stipulated at 90-95%. This figure does not easily translate into age-specific immunity levels required to interrupt transmission. Previous estimates of such levels were based on speculative contact patterns based on historical data from high-income countries. The aim of this study was to determine age-specific immunity levels that would ensure elimination of measles when taking into account empirically observed contact patterns. Methods: We combined estimated immunity levels from serological data in 17 countries with studies of age-specific mixing patterns to derive contact-adjusted immunity levels. We then compared these to case data from the 10 years following the seroprevalence studies to establish a contact-adjusted immunity threshold for elimination. We lastly combined a range of hypothetical immunity profiles with contact data from a wide range of socioeconomic and demographic settings to determine whether they would be sufficient for elimination. Results: We found that contact-adjusted immunity levels were able to predict whether countries would experience outbreaks in the decade following the serological studies in about 70% of countries. The corresponding threshold level of contact-adjusted immunity was found to be 93%, corresponding to an average basic reproduction number of approximately 14. Testing different scenarios of immunity with this threshold level using contact studies from around the world, we found that 95% immunity would have to be achieved by the age of five and maintained across older age groups to guarantee elimination. This reflects a greater level of immunity required in 5-9-year-olds than established previously. Conclusions: The immunity levels we found necessary for measles elimination are higher than previous guidance. The importance of achieving high immunity levels in 5-9-year-olds presents both a challenge and an opportunity. While such high levels can be difficult to achieve, school entry provides an opportunity to ensure sufficient vaccination coverage. Combined with observations of contact patterns, further national and sub-national serological studies could serve to highlight key gaps in immunity that need to be filled in order to achieve national and regional measles elimination.Determinants of methicillin-resistant Staphylococcus aureus (MRSA) prevalence in the Asia-Pacific region: A systematic review and meta-analysis
AbstractLim, W. W., Wu, P., Bond, H. S., Wong, J. Y., Ni, K., Seto, W. H., Jit, M., & Cowling, B. J. (n.d.).Publication year
2019Journal title
Journal of Global Antimicrobial ResistanceVolume
16Page(s)
17-27AbstractObjectives: Published literature on methicillin-resistant Staphylococcus aureus (MRSA) in the Asia–Pacific region was reviewed to document the prevalence of MRSA in the region and to examine the impact of variability in study design on the reported MRSA prevalence data. Methods: This review included studies reporting MRSA prevalence between 2000 and 2016. Studies were excluded if they did not contain complete information on antimicrobial susceptibility testing (AST) methods. Primary outcomes were the proportion of MRSA among S. aureus isolates (resistance proportion) or among individual samples (prevalence). Results: A total of 229 studies in 19 countries/territories were included in the study. There was substantial heterogeneity in both outcomes (resistance proportion, I 2 = 99.59%; prevalence, I 2 = 99.83%), precluding pooled averages, and meta-regression analyses revealed that these variations were explained by country income status and participant characteristics but not by methodological differences in AST. Also, no significant secular changes in MRSA prevalence or resistance proportions in Asia-Pacific were found. Conclusion: The resistance proportions and prevalence of MRSA infections in Asia-Pacific are comparable with those reported in other regions with no significant secular changes in the past decade. Country income status and characteristics of the sample population explained more variation in the reported resistance proportions and prevalence of MRSA than methodological differences in AST across locations in the region.Effect and cost-effectiveness of pneumococcal conjugate vaccination: a global modelling analysis
AbstractChen, C., Cervero Liceras, F., Flasche, S., Sidharta, S., Yoong, J., Sundaram, N., & Jit, M. (n.d.).Publication year
2019Journal title
The Lancet Global HealthVolume
7Issue
1Page(s)
e58-e67AbstractBackground: Introduction of pneumococcal conjugate vaccines (PCVs) has substantially reduced disease burden due to Streptococcus pneumoniae, a leading cause of childhood morbidity and mortality globally. However, PCVs are among the most expensive vaccines, hindering their introduction in some settings and threatening sustainability in others. We aimed to assess the effect and cost-effectiveness of introduction of 13-valent PCV (PCV13) vaccination globally. Methods: We assessed the incremental cost-effectiveness ratio of PCV13 introduction by integrating two models: an ecological model (a parsimonious, mechanistic model validated with data from post-seven-valent PCV introduction in 13 high-income settings) to predict the effect of PCV on childhood invasive pneumococcal disease, and a decision-tree model to predict a range of clinical presentations and economic outcomes under vaccination and no-vaccination strategies. The models followed 30 birth cohorts up to age 5 years in 180 countries from 2015 to 2045. One-way scenario and probabilistic sensitivity analyses were done to explore model uncertainties. Findings: We estimate that global PCV13 use could prevent 0·399 million child deaths (95% credible interval 0·208 million to 0·711 million) and 54·6 million disease episodes (51·8 million to 58·1 million) annually. Global vaccine costs (in 2015 international dollars) of $15·5 billion could be partially offset by health-care savings of $3·19 billion (2·62 billion to 3·92 billion) and societal cost savings of $2·64 billion (2·13 billion to 3·28 billion). PCV13 use is probably cost-effective in all six UN regions. The 71 countries eligible for support from Gavi, the Vaccine Alliance, account for 83% of PCV13-preventable deaths but only 18% of global vaccination costs. The expected cost of PCV vaccination globally is around $16 billion per year. Interpretation: Our findings highlight the value of Gavi's support for PCV introduction in low-income countries and of efforts to improve the affordability of PCVs in countries not eligible for, or transitioning from, Gavi support. Funding: World Health Organization; Gavi, the Vaccine Alliance; and the Bill & Melinda Gates Foundation.