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
Stark choices : Exploring health sector costs of policy responses to COVID-19 in low-income and middle-income countries
AbstractTorres-Rueda, S., Sweeney, S., Bozzani, F., Naylor, N. R., Baker, T., Pearson, C., Eggo, R., Procter, S. R., Davies, N., Quaife, M., Kitson, N., Keogh-Brown, M. R., Jensen, H. T., Saadi, N., Khan, M., Huda, M., Kairu, A., Zaidi, R., Barasa, E., … Vassall, A. (n.d.).Publication year
2021Journal title
BMJ Global HealthVolume
6Issue
12AbstractObjectives: COVID-19 has altered health sector capacity in low-income and middle-income countries (LMICs). Cost data to inform evidence-based priority setting are urgently needed. Consequently, in this paper, we calculate the full economic health sector costs of COVID-19 clinical management in 79 LMICs under different epidemiological scenarios. Methods: We used country-specific epidemiological projections from a dynamic transmission model to determine number of cases, hospitalisations and deaths over 1 year under four mitigation scenarios. We defined the health sector response for three base LMICs through guidelines and expert opinion. We calculated costs through local resource use and price data and extrapolated costs across 79 LMICs. Lastly, we compared cost estimates against gross domestic product (GDP) and total annual health expenditure in 76 LMICs. Results: COVID-19 clinical management costs vary greatly by country, ranging betweenStrategies to reduce the risk of SARS-CoV-2 importation from international travellers : Modelling estimations for the United Kingdom, July 2020
AbstractCMMID COVID-19 Working Group, A., Clifford, S., Quilty, B. J., Russell, T. W., Liu, Y., Chan, Y. W., Pearson, C. A., Eggo, R. M., Endo, A., Flasche, S., John Edmunds, W., Sherratt, K., Hué, S., Quaife, M., Bosse, N. I., Medley, G., Auzenbergs, M., Kucharski, A. J., Davies, N. G., … Abbas, K. (n.d.).Publication year
2021Journal title
EurosurveillanceVolume
26Issue
39AbstractBackground: To mitigate SARS-CoV-2 transmission risks from international air travellers, many countries implemented a combination of up to 14 days of self-quarantine upon arrival plus PCR testing in the early stages of the COVID-19 pandemic in 2020. Aim: To assess the effectiveness of quarantine and testing of international travellers to reduce risk of onward SARS-CoV-2 transmission into a destination country in the pre-COVID-19 vaccination era. Methods: We used a simulation model of air travellers arriving in the United Kingdom from the European Union or the United States, incorporating timing of infection stages while varying quarantine duration and timing and number of PCR tests. Results: Quarantine upon arrival with a PCR test on day 7 plus a 1-day delay for results can reduce the number of infectious arriving travellers released into the community by a median 94% (95% uncertainty interval (UI): 89–98) compared with a no quarantine/no test scenario. This reduction is similar to that achieved by a 14-day quarantine period (median>99%; 95% UI: 98–100). Even shorter quarantine periods can prevent a substantial amount of transmission; all strategies in which travellers spend at least 5 days (mean incubation period) in quarantine and have at least one negative test before release are highly effective (median reduction 89%; 95% UI: 83–95)). Conclusion: The effect of different screening strategies impacts asymptomatic and symptomatic individuals differently. The choice of an optimal quarantine and testing strategy for unvaccinated air travellers may vary based on the number of possible imported infections relative to domestic incidence.The CAPACITI Decision-Support Tool for National Immunization Programs
AbstractBotwright, S., Giersing, B. K., Meltzer, M. I., Kahn, A. L., Jit, M., Baltussen, R., El Omeiri, N., Biey, J. N., Moore, K. L., Thokala, P., Mwenda, J. M., Bertram, M., & Hutubessy, R. C. (n.d.).Publication year
2021Journal title
Value in HealthVolume
24Issue
8Page(s)
1150-1157AbstractObjectives: Immunization programs in low-income and middle-income countries (LMICs) are faced with an ever-growing number of vaccines of public health importance recommended by the World Health Organization, while also financing a greater proportion of the program through domestic resources. More than ever, national immunization programs must be equipped to contextualize global guidance and make choices that are best suited to their setting. The CAPACITI decision-support tool has been developed in collaboration with national immunization program decision makers in LMICs to structure and document an evidence-based, context-specific process for prioritizing or selecting among multiple vaccination products, services, or strategies. Methods: The CAPACITI decision-support tool is based on multi-criteria decision analysis, as a structured way to incorporate multiple sources of evidence and stakeholder perspectives. The tool has been developed iteratively in consultation with 12 countries across Africa, Asia, and the Americas. Results: The tool is flexible to existing country processes and can follow any type of multi-criteria decision analysis or a hybrid approach. It is structured into 5 sections: decision question, criteria for decision making, evidence assessment, appraisal, and recommendation. The Excel-based tool guides the user through the steps and document discussions in a transparent manner, with an emphasis on stakeholder engagement and country ownership. Conclusions: Pilot countries valued the CAPACITI decision-support tool as a means to consider multiple criteria and stakeholder perspectives and to evaluate trade-offs and the impact of data quality. With use, it is expected that LMICs will tailor steps to their context and streamline the tool for decision making.The impact of childhood pneumococcal conjugate vaccine immunisation on all-cause pneumonia admissions in Hong Kong : A 14-year population-based interrupted time series analysis
AbstractYu, Q., Li, X., Fan, M., Qiu, H., Wong, A. Y., Tian, L., Chui, C. S., Li, P. H., Lau, L. K., Chan, E. W., Goggins, W. B., Ip, P., Lum, T. Y., Hung, I. F., Cowling, B. J., Wong, I. C., & Jit, M. (n.d.).Publication year
2021Journal title
VaccineVolume
39Issue
19Page(s)
2628-2635AbstractBackground: Nine years after the introduction of pneumococcal conjugate vaccine (PCV) in the United States, Hong Kong (HK) introduced the vaccine to its universal childhood immunisation programme in 2009. We aimed to assess the impact of childhood PCV immunisation on all-cause pneumonia (ACP) admissions among the overall population of HK. Methods: In this population-based interrupted time series analysis, we used territory-wide population-representative electronic health records in HK to evaluate the vaccine impact. We identified hospitalised patients with a diagnosis of pneumonia from any cause between 2004 and 2017. We applied segmented Poisson regression to assess the gradual change in the monthly incidence of ACP admissions between pre- and post-vaccination periods. Negative outcome control, subgroup and sensitivity analyses were used to test the robustness of the main analysis. Findings: Over the 14-year study period, a total of 587,607 ACP episodes were identified among 357,950 patients. The monthly age-standardised incidence of ACP fluctuated between 33.42 and 87.44 per 100,000-persons. There was a marginal decreasing trend in pneumonia admissions after PCV introduction among overall population (incidence rate ratio [IRR]: 0·9965, 95% confidence interval [CI]: 0·9932–0·9998), and older adults (≥65 years, IRR: 0·9928, 95% CI: 0·9904–0·9953) but not in younger age groups. Interpretation: There was a marginally declining trend of overall ACP admissions in HK up to eight years after childhood PCV introduction. The significance disappeared when fitting sensitivity analyses. The results indicate the complexities of using non-specific endpoints for measuring vaccine effect and the necessity of enhancing serotype surveillance systems for replacement monitoring. Funding: Health and Medical Research Fund, Food and Health Bureau of the Government of Hong Kong (Reference number: 18171272).The impact of local and national restrictions in response to COVID-19 on social contacts in England : a longitudinal natural experiment
AbstractCMMID COVID-19 Working Group, A., Jarvis, C. I., Gimma, A., van Zandvoort, K., Wong, K. L., Abbas, K., Villabona-Arenas, C. J., O’Reilly, K., Quaife, M., Rosello, A., Kucharski, A. J., Gibbs, H. P., Atkins, K. E., Barnard, R. C., Bosse, N. I., Procter, S. R., Meakin, S. R., Sun, F. Y., Abbott, S., … Klepac, P. (n.d.).Publication year
2021Journal title
BMC MedicineVolume
19Issue
1AbstractBackground: England’s COVID-19 response transitioned from a national lockdown to localised interventions. In response to rising cases, these were supplemented by national restrictions on contacts (the Rule of Six), then 10 pm closing for bars and restaurants, and encouragement to work from home. These were quickly followed by a 3-tier system applying different restrictions in different localities. As cases continued to rise, a second national lockdown was declared. We used a national survey to quantify the impact of these restrictions on epidemiologically relevant contacts. Methods: We compared paired measures on setting-specific contacts before and after each restriction started and tested for differences using paired permutation tests on the mean change in contacts and the proportion of individuals decreasing their contacts. Results: Following the imposition of each measure, individuals tended to report fewer contacts than they had before. However, the magnitude of the changes was relatively small and variable. For instance, although early closure of bars and restaurants appeared to have no measurable effect on contacts, the work from home directive reduced mean daily work contacts by 0.99 (95% confidence interval CI] 0.03–1.94), and the Rule of Six reduced non-work and school contacts by a mean of 0.25 (0.01–0.5) per day. Whilst Tier 3 appeared to also reduce non-work and school contacts, the evidence for an effect of the lesser restrictions (Tiers 1 and 2) was much weaker. There may also have been some evidence of saturation of effects, with those who were in Tier 1 (least restrictive) reducing their contacts markedly when they entered lockdown, which was not reflected in similar changes in those who were already under tighter restrictions (Tiers 2 and 3). Conclusions: The imposition of various local and national measures in England during the summer and autumn of 2020 has gradually reduced contacts. However, these changes are smaller than the initial lockdown in March. This may partly be because many individuals were already starting from a lower number of contacts.The impact of non-pharmaceutical interventions on SARS-CoV-2 transmission across 130 countries and territories
AbstractCMMID COVID-19 Working Group, A., Liu, Y., Morgenstern, C., Kelly, J., Lowe, R., Munday, J., Villabona-Arenas, C. J., Gibbs, H., Pearson, C. A., Prem, K., Leclerc, Q. J., Meakin, S. R., Edmunds, W. J., Jarvis, C. I., Gimma, A., Funk, S., Quaife, M., Russell, T. W., Emory, J. C., … Jit, M. (n.d.).Publication year
2021Journal title
BMC MedicineVolume
19Issue
1AbstractBackground: Non-pharmaceutical interventions (NPIs) are used to reduce transmission of SARS coronavirus 2 (SARS-CoV-2) that causes coronavirus disease 2019 (COVID-19). However, empirical evidence of the effectiveness of specific NPIs has been inconsistent. We assessed the effectiveness of NPIs around internal containment and closure, international travel restrictions, economic measures, and health system actions on SARS-CoV-2 transmission in 130 countries and territories. Methods: We used panel (longitudinal) regression to estimate the effectiveness of 13 categories of NPIs in reducing SARS-CoV-2 transmission using data from January to June 2020. First, we examined the temporal association between NPIs using hierarchical cluster analyses. We then regressed the time-varying reproduction number (Rt) of COVID-19 against different NPIs. We examined different model specifications to account for the temporal lag between NPIs and changes in Rt, levels of NPI intensity, time-varying changes in NPI effect, and variable selection criteria. Results were interpreted taking into account both the range of model specifications and temporal clustering of NPIs. Results: There was strong evidence for an association between two NPIs (school closure, internal movement restrictions) and reduced Rt. Another three NPIs (workplace closure, income support, and debt/contract relief) had strong evidence of effectiveness when ignoring their level of intensity, while two NPIs (public events cancellation, restriction on gatherings) had strong evidence of their effectiveness only when evaluating their implementation at maximum capacity (e.g. restrictions on 1000+ people gathering were not effective, restrictions on < 10 people gathering were). Evidence about the effectiveness of the remaining NPIs (stay-at-home requirements, public information campaigns, public transport closure, international travel controls, testing, contact tracing) was inconsistent and inconclusive. We found temporal clustering between many of the NPIs. Effect sizes varied depending on whether or not we included data after peak NPI intensity. Conclusion: Understanding the impact that specific NPIs have had on SARS-CoV-2 transmission is complicated by temporal clustering, time-dependent variation in effects, and differences in NPI intensity. However, the effectiveness of school closure and internal movement restrictions appears robust across different model specifications, with some evidence that other NPIs may also be effective under particular conditions. This provides empirical evidence for the potential effectiveness of many, although not all, actions policy-makers are taking to respond to the COVID-19 pandemic.The importance of saturating density dependence for population-level predictions of SARS-CoV-2 resurgence compared with density-independent or linearly density-dependent models, England, 23 March to 31 July 2020
AbstractCMMID COVID-19 Working Group, A., Nightingale, E. S., Brady, O. J., Yakob, L., Gimma, A., Jit, M., Jarvis, C. I., Waterlow, N. R., Procter, S. R., Auzenbergs, M., Tully, D. C., Simons, D., Endo, A., Hellewell, J., Lowe, R., Foss, A. M., van Zandvoort, K., Pearson, C. A., Showering, A., … Clifford, S. (n.d.).Publication year
2021Journal title
EurosurveillanceVolume
26Issue
49AbstractBackground: Population-level mathematical models of outbreaks typically assume that disease transmission is not impacted by population density (‘frequency-dependent’) or that it increases linearly with density (‘density-dependent’). Aim: We sought evidence for the role of population density in SARS-CoV-2 transmission. Methods: Using COVID-19-associated mortality data from England, we fitted multiple functional forms linking density with transmission. We projected forwards beyond lockdown to ascertain the consequences of different functional forms on infection resurgence. Results: COVID-19-associated mortality data from England show evidence of increasing with population density until a saturating level, after adjusting for local age distribution, deprivation, proportion of ethnic minority population and proportion of key workers among the working population. Projections from a mathematical model that accounts for this observation deviate markedly from the current status quo for SARS-CoV-2 models which either assume linearity between density and transmission (30% of models) or no relationship at all (70%). Respectively, these classical model structures over- and underestimate the delay in infection resurgence following the release of lockdown. Conclusion: Identifying saturation points for given populations and including transmission terms that account for this feature will improve model accuracy and utility for the current and future pandemics.The importance of supplementary immunisation activities to prevent measles outbreaks during the COVID-19 pandemic in Kenya
AbstractJit, M., LSHTM CMMID COVID-19 Working Group, A., Mburu, C. N., Ojal, J., Chebet, R., Akech, D., Karia, B., Tuju, J., Sigilai, A., Abbas, K., Jit, M., Funk, S., Smits, G., van Gageldonk, P. G., van der Klis, F. R., Tabu, C., Nokes, D. J., Munday, J. D., Pearson, C. A., … Quaife, M. (n.d.).Publication year
2021Journal title
BMC MedicineVolume
19Issue
1AbstractBackground: The COVID-19 pandemic has disrupted routine measles immunisation and supplementary immunisation activities (SIAs) in most countries including Kenya. We assessed the risk of measles outbreaks during the pandemic in Kenya as a case study for the African Region. Methods: Combining measles serological data, local contact patterns, and vaccination coverage into a cohort model, we predicted the age-adjusted population immunity in Kenya and estimated the probability of outbreaks when contact-reducing COVID-19 interventions are lifted. We considered various scenarios for reduced measles vaccination coverage from April 2020. Results: In February 2020, when a scheduled SIA was postponed, population immunity was close to the herd immunity threshold and the probability of a large outbreak was 34% (8–54). As the COVID-19 contact restrictions are nearly fully eased, from December 2020, the probability of a large measles outbreak will increase to 38% (19–54), 46% (30–59), and 54% (43–64) assuming a 15%, 50%, and 100% reduction in measles vaccination coverage. By December 2021, this risk increases further to 43% (25–56), 54% (43–63), and 67% (59–72) for the same coverage scenarios respectively. However, the increased risk of a measles outbreak following the lifting of all restrictions can be overcome by conducting a SIA with ≥ 95% coverage in under-fives. Conclusion: While contact restrictions sufficient for SAR-CoV-2 control temporarily reduce measles transmissibility and the risk of an outbreak from a measles immunity gap, this risk rises rapidly once these restrictions are lifted. Implementing delayed SIAs will be critical for prevention of measles outbreaks given the roll-back of contact restrictions in Kenya.The potential for vaccination-induced herd immunity against the SARS-CoV-2 B.1.1.7 variant
AbstractCMMID COVID-19 Working Group, A., Hodgson, D., Flasche, S., Jit, M., Kucharski, A. J., Abbott, S., Edmunds, W. J., Davies, N. G., Eggo, R. M., Medley, G., Lei, J., Liu, Y., Tully, D. C., McCarthy, C. V., Mee, P., Endo, A., Hellewell, J., Funk, S., Jombart, T., … Abbas, K. (n.d.).Publication year
2021Journal title
EurosurveillanceVolume
26Issue
20AbstractWe assess the feasibility of reaching the herd immunity threshold against SARS-CoV-2 through vaccination, considering vaccine effectiveness (VE), transmissibility of the virus and the level of pre-existing immunity in populations, as well as their age structure. If highly transmissible variants of concern become dominant in areas with low levels of naturally-acquired immunity and/or in populations with large proportions of < 15 year-olds, control of infection without non-pharmaceutical interventions may only be possible with a VE ≥ 80%, and coverage extended to children. Initial reports of vaccine effectiveness against severe acute respiratory syndrome coronavirus 2 (SARSCoV-2), the virus responsible for coronavirus disease (COVID-19), have suggested a substantial reduction of the risk of infection [1]. Nevertheless, with the emergence of more transmissible variants such as B.1.1.7 [2], how large-scale immunisation programmes against SARS-CoV-2 will perform is currently unclear. This study assesses the potential of COVID-19 vaccination to generate herd immunity and takes into account vaccine effectiveness, naturally-acquired immunity and achievable vaccination coverage (depending on the population age structure), as well as two transmissibility scenarios ((i) with pre-B.1.1.7, and (ii) with exclusively B.1.1.7 variants).The potential health and economic value of SARS-CoV-2 vaccination alongside physical distancing in the UK : a transmission model-based future scenario analysis and economic evaluation
AbstractCentre for the Mathematical Modelling of Infectious Diseases COVID-19 working group, A., Sandmann, F. G., Davies, N. G., Vassall, A., Edmunds, W. J., Jit, M., Sun, F. Y., Villabona-Arenas, C. J., Nightingale, E. S., Showering, A., Knight, G. M., Sherratt, K., Liu, Y., Abbas, K., Funk, S., Endo, A., Hellewell, J., Rosello, A., Lowe, R., … Clifford, S. (n.d.).Publication year
2021Journal title
The Lancet Infectious DiseasesVolume
21Issue
7Page(s)
962-974AbstractBackground: In response to the COVID-19 pandemic, the UK first adopted physical distancing measures in March, 2020. Vaccines against SARS-CoV-2 became available in December, 2020. We explored the health and economic value of introducing SARS-CoV-2 immunisation alongside physical distancing in the UK to gain insights about possible future scenarios in a post-vaccination era. Methods: We used an age-structured dynamic transmission and economic model to explore different scenarios of UK mass immunisation programmes over 10 years. We compared vaccinating 75% of individuals aged 15 years or older (and annually revaccinating 50% of individuals aged 15–64 years and 75% of individuals aged 65 years or older) to no vaccination. We assumed either 50% vaccine efficacy against disease and 45-week protection (worst-case scenario) or 95% vaccine efficacy against infection and 3-year protection (best-case scenario). Natural immunity was assumed to wane within 45 weeks. We also explored the additional impact of physical distancing on vaccination by assuming either an initial lockdown followed by voluntary physical distancing, or an initial lockdown followed by increased physical distancing mandated above a certain threshold of incident daily infections. We considered benefits in terms of quality-adjusted life-years (QALYs) and costs, both to the health-care payer and the national economy. We discounted future costs and QALYs at 3·5% annually and assumed a monetary value per QALY of £20 000 and a conservative long-run cost per vaccine dose of £15. We explored and varied these parameters in sensitivity analyses. We expressed the health and economic benefits of each scenario with the net monetary value: QALYs × (monetary value per QALY) – costs. Findings: Without the initial lockdown, vaccination, and increased physical distancing, we estimated 148·0 million (95% uncertainty interval 48·5–198·8) COVID-19 cases and 3·1 million (0·84–4·5) deaths would occur in the UK over 10 years. In the best-case scenario, vaccination minimises community transmission without future periods of increased physical distancing, whereas SARS-CoV-2 becomes endemic with biannual epidemics in the worst-case scenario. Ongoing transmission is also expected in intermediate scenarios with vaccine efficacy similar to published clinical trial data. From a health-care perspective, introducing vaccination leads to incremental net monetary values ranging from £12·0 billion to £334·7 billion in the best-case scenario and from –£1·1 billion to £56·9 billion in the worst-case scenario. Incremental net monetary values of increased physical distancing might be negative from a societal perspective if national economy losses are persistent and large. Interpretation: Our model findings highlight the substantial health and economic value of introducing SARS-CoV-2 vaccination. Smaller outbreaks could continue even with vaccines, but population-wide implementation of increased physical distancing might no longer be justifiable. Our study provides early insights about possible future post-vaccination scenarios from an economic and epidemiological perspective. Funding: National Institute for Health Research, European Commission, Bill & Melinda Gates Foundation.Who should be prioritized for COVID-19 vaccination in China? A descriptive study
AbstractYang, J., Zheng, W., Shi, H., Yan, X., Dong, K., You, Q., Zhong, G., Gong, H., Chen, Z., Jit, M., Viboud, C., Ajelli, M., & Yu, H. (n.d.).Publication year
2021Journal title
BMC MedicineVolume
19Issue
1AbstractBackground: All countries are facing decisions about which population groups to prioritize for access to COVID-19 vaccination after the first vaccine products have been licensed, at which time supply shortages are inevitable. Our objective is to define the key target populations, their size, and priority for a COVID-19 vaccination program in the context of China. Methods: On the basis of utilitarian and egalitarian principles, we define and estimate the size of tiered target population groups for a phased introduction of COVID-19 vaccination, considering evolving goals as vaccine supplies increase, detailed information on the risk of illness and transmission, and past experience with vaccination during the 2009 influenza pandemic. Using publicly available data, we estimated the size of target population groups, and the number of days needed to vaccinate 70% of the target population. Sensitivity analyses considered higher vaccine coverages and scaled up vaccine delivery relative to the 2009 pandemic. Results: Essential workers, including staff in the healthcare, law enforcement, security, nursing homes, social welfare institutes, community services, energy, food and transportation sectors, and overseas workers/students (49.7 million) could be prioritized for vaccination to maintain essential services in the early phase of a vaccination program. Subsequently, older adults, individuals with underlying health conditions and pregnant women (563.6 million) could be targeted for vaccination to reduce the number of individuals with severe COVID-19 outcomes, including hospitalizations, critical care admissions, and deaths. In later stages, the vaccination program could be further extended to target adults without underlying health conditions and children (784.8 million), in order to reduce symptomatic infections and/or to stop virus transmission. Given 10 million doses administered per day, and a two-dose vaccination schedule, it would take 1 week to vaccinate essential workers but likely up to 7 months to vaccinate 70% of the overall population. Conclusions: The proposed framework is general but could assist Chinese policy-makers in the design of a vaccination program. Additionally, this exercise could be generalized to inform other national and regional strategies for use of COVID-19 vaccines, especially in low- and middle-income countries.World Health Organization Expert Working Group : Recommendations for assessing morbidity associated with enteric pathogens
AbstractHasso-Agopsowicz, M., Lopman, B. A., Lanata, C. F., Rogawski McQuade, E. T., Kang, G., Prudden, H. J., Khalil, I., Platts-Mills, J. A., Kotloff, K., Jit, M., Riddle, M. S., Pavlinac, P. B., Luz, P. M., Pitzer, V. E., Breiman, R. F., & Giersing, B. K. (n.d.).Publication year
2021Journal title
VaccineVolume
39Issue
52Page(s)
7521-7525AbstractBackground: Diarrhoeal infections are one of the leading causes of child's mortality and morbidity. Vaccines against Shigella, enterotoxigenic E. coli (ETEC), norovirus and invasive non-typhoidal Salmonella are in clinical development, however, their full value in terms of short and long-term health and socio-economic burden needs to be evaluated and communicated, to rationalise investment in vaccine development, and deployment. While estimates of mortality of enteric infections exist, the long-term morbidity estimates are scarce and have not been systematically collected. Methods: The World Health Organization (WHO) has convened a Burden of Enteric Diseases Morbidity Working Group (BoED MWG) who identified key workstreams needed to characterise the morbidity burden of enteric infections. The group also identified four criteria for the prioritisation of pathogens of which impact on long-term morbidity needs to be assessed. Results: The BoED MWG suggested to identify and analyse the individual level data from historical datasets to estimate the impact of enteric infections and confounders on long-term morbidity, including growth faltering and cognitive impairment in children (workstream 1); to conduct a systematic review of evidence on the association of aetiology specific diarrhoea with short- and long- term impact on growth, including stunting, and possibly cognitive impairment in children, while accounting for potential confounders (workstream 2); and to conduct a systematic review of evidence on the association of aetiology specific diarrhoea with short- and long- term impact on health outcomes in adults. The experts prioritised four pathogens for this work: Campylobacter jejuni, ETEC (LT or ST), norovirus (G1 or G2), and Shigella (dysenteriae, flexneri, sonnei). Conclusions: The proposed work will contribute to improving the understanding of the impact of enteric pathogens on long-term morbidity. The timing of this work is critical as all four pathogens have vaccine candidates in the clinical pipeline and decisions about investments in development, manufacturing or vaccine procurement and use are expected to be made soon.A review of the costs of delivering maternal immunisation during pregnancy
AbstractProcter, S. R., Salman, O., Pecenka, C., Gonçalves, B. P., Paul, P., Hutubessy, R., Lambach, P., Lawn, J. E., & Jit, M. (n.d.).Publication year
2020Journal title
VaccineVolume
38Issue
40Page(s)
6199-6204AbstractBackground: Routine maternal immunisation against influenza and pertussis are recommended by the WHO to protect mother and child, and new vaccines are under development. Introducing maternal vaccines into national programmes requires an understanding of vaccine delivery costs – particularly in low resource settings. Methods: We searched Medline, Embase, Econlit, and Global Health for studies reporting costs of delivering vaccination during pregnancy but excluded studies that did not separate the vaccine purchase price. Extracted costs were inflated and converted to 2018 US dollars. Results: Sixteen studies were included, of which two used primary data to estimate vaccine delivery costs. Costs per dose ranged from $0.55 to $0.64 in low-income countries, from $1.25 to $6.55 for middle-income countries, and from $5.76 to $39.87 in high-income countries. Conclusions: More research is needed on the costs of delivering maternal immunisation during pregnancy, and of integrating vaccine delivery into existing programmes of antenatal care especially in low and middle-income countries.Access and Unmet Needs of Orphan Drugs in 194 Countries and 6 Areas : A Global Policy Review With Content Analysis
AbstractChan, A. Y., Chan, V. K., Olsson, S., Fan, M., Jit, M., Gong, M., Zhang, S., Ge, M., Pathadka, S., Chung, C. C., Chung, B. H., Chui, C. S., Chan, E. W., Wong, G. H., Lum, T. Y., Wong, I. C., Ip, P., & Li, X. (n.d.).Publication year
2020Journal title
Value in HealthVolume
23Issue
12Page(s)
1580-1591AbstractObjectives: Three hundred million people living with rare diseases worldwide are disproportionately deprived of in-time diagnosis and treatment compared with other patients. This review provides an overview of global policies that optimize development, licensing, pricing, and reimbursement of orphan drugs. Methods: Pharmaceutical legislation and policies related to access and regulation of orphan drugs were examined from 194 World Health Organization member countries and 6 areas. Orphan drug policies (ODPs) were identified through internet search, emails to national pharmacovigilance centers, and systematic academic literature search. Texts from selected publications were extracted for content analysis. Results: One hundred seventy-two drug regulation documents and 77 academic publications from 162 countries/areas were included. Ninety-two of 200 countries/areas (46.0%) had documentation on ODPs. Thirty-four subthemes from content analysis were categorized into 6 policy themes, namely, orphan drug designation, marketing authorization, safety and efficacy requirements, price regulation, incentives that encourage market availability, and incentives that encourage research and development. Countries/areas with ODPs were statistically wealthier (gross national income per capita = $10 875 vs $3950, PAge-dependent effects in the transmission and control of COVID-19 epidemics
AbstractCMMID COVID-19 Working Group, A., Davies, N. G., Klepac, P., Liu, Y., Prem, K., Jit, M., Pearson, C. A., Quilty, B. J., Kucharski, A. J., Gibbs, H., Clifford, S., Gimma, A., van Zandvoort, K., Munday, J. D., Diamond, C., Edmunds, W. J., Houben, R. M., Hellewell, J., Russell, T. W., … Eggo, R. M. (n.d.).Publication year
2020Journal title
Nature MedicineVolume
26Issue
8Page(s)
1205-1211AbstractThe COVID-19 pandemic has shown a markedly low proportion of cases among children1–4. Age disparities in observed cases could be explained by children having lower susceptibility to infection, lower propensity to show clinical symptoms or both. We evaluate these possibilities by fitting an age-structured mathematical model to epidemic data from China, Italy, Japan, Singapore, Canada and South Korea. We estimate that susceptibility to infection in individuals under 20 years of age is approximately half that of adults aged over 20 years, and that clinical symptoms manifest in 21% (95% credible interval: 12–31%) of infections in 10- to 19-year-olds, rising to 69% (57–82%) of infections in people aged over 70 years. Accordingly, we find that interventions aimed at children might have a relatively small impact on reducing SARS-CoV-2 transmission, particularly if the transmissibility of subclinical infections is low. Our age-specific clinical fraction and susceptibility estimates have implications for the expected global burden of COVID-19, as a result of demographic differences across settings. In countries with younger population structures—such as many low-income countries—the expected per capita incidence of clinical cases would be lower than in countries with older population structures, although it is likely that comorbidities in low-income countries will also influence disease severity. Without effective control measures, regions with relatively older populations could see disproportionally more cases of COVID-19, particularly in the later stages of an unmitigated epidemic.Assessing the value of human papillomavirus vaccination in Gavi-eligible low-income and middle-income countries
AbstractOchalek, J., Abbas, K., Claxton, K., Jit, M., & Lomas, J. (n.d.).Publication year
2020Journal title
BMJ Global HealthVolume
5Issue
10AbstractIntroduction Estimating the value of providing effective healthcare interventions in a country requires an assessment of whether the improvement in health outcomes they offer exceeds the improvement in health that would have been possible if the resources required had, instead, been made available for other healthcare activities in that country. This potential alternative use of the same resources represents the health opportunity cost of providing the intervention. Without such assessments, there is a danger that blanket recommendations made by international organisations will lead to the adoption of healthcare interventions that are not cost effective in some countries, even given existing donor mechanisms intended to support their affordability. Methods We assessed the net health impact to 46 Gavi-eligible countries of achieving one of the WHO's proposed 90-70-90 targets for cervical cancer elimination, which includes 90% coverage of human papillomavirus (HPV) vaccination among girls by 15 years of age, using published estimates of the expected additional benefits and costs in each country and estimates of the marginal productivity of each healthcare system. We calculated the maximum price each country could afford to pay for HPV vaccination to be cost effective by assessing the net health impact that would be expected to be generated at different potential prices. Results At Gavi negotiated prices, HPV vaccination offers net health benefits across most Gavi-eligible countries included in this study. However, if Gavi-eligible countries faced the average price faced by non-Gavi eligible countries, providing HPV vaccination would result in reduced overall population health in most countries. Conclusion Estimates of the net health impact of providing a healthcare intervention can be used to assess the benefit (or lack of) to countries of adhering to global guidance, inform negotiations with donors, as well as pricing negotiations and the value of developing new healthcare interventions.Burden and Cost of Hospitalization for Respiratory Syncytial Virus in Young Children, Singapore
AbstractTam, C. C., Tam, C. C., Tam, C. C., Tam, C. C., Yeo, K. T., Yeo, K. T., Tee, N., Tee, N., Lin, R., Mak, T. M., Thoon, K. C., Jit, M., Yung, C. F., Yung, C. F., & Yung, C. F. (n.d.).Publication year
2020Journal title
Emerging Infectious DiseasesVolume
26Issue
7Page(s)
1489-1496AbstractRespiratory syncytial virus (RSV) is the most common cause of pediatric acute lower respiratory tract infection worldwide. Detailed data on the health and economic burden of RSV disease are lacking from tropical settings with year-round RSV transmission. We developed a statistical and economic model to estimate the annual incidence and healthcare cost of medically attended RSV disease among young children in Singapore, using Monte Carlo simulation to account for uncertainty in model param-eters. RSV accounted for 708 hospitalizations in childrenCaregiver and service provider vaccine confidence following the Changchun Changsheng vaccine incident in China : A cross-sectional mixed methods study
AbstractTu, S., Sun, F. Y., Chantler, T., Zhang, X., Jit, M., Han, K., Rodewald, L., Du, F., Yu, H., Hou, Z., & Larson, H. (n.d.).Publication year
2020Journal title
VaccineVolume
38Issue
44Page(s)
6882-6888AbstractIntroduction: The Changchun Changsheng Vaccine Incident (CCVI) occurred mid-2018 and involved irregularities in the manufacture and quality control of diphtheria-tetanus-acellular-pertussis and rabies vaccines. This study investigates vaccine confidence amongst Chinese caregivers and vaccination-service providers (VSPs) six months after the CCVI. Methods: Quantitative surveys were conducted in January 2019 with 2124 caregivers of children and 555 VSPs in three areas in China. The proportions of respondents who agreed to the four statements from the Vaccine Confidence Index™ were used to measure vaccine confidence. Descriptive and univariate analyses were performed to study the level of vaccine confidence. Semi-structured interviews were conducted with 48 caregivers, 43 VSPs and 9 immunization program managers. Interviews were analyzed thematically using a combination of deductive and inductive coding. Media surveillance was conducted to monitor public responses to the CCVI. Results: Media surveillance indicated that public attention to vaccine-related issues increased sharply immediately post-CCVI but declined rapidly thereafter. Six months post-CCVI, 96.0% of caregivers and the same proportion of VSPs reported that vaccination was important and compatible with their religious beliefs. 82.7% and 88.2% of caregivers agreed that vaccines were safe and effective. 92.8% and 94.6% of VSPs agreed that vaccines were safe and effective. Both caregivers and VSPs reported an immediate decline in vaccine confidence post-CCVI. In most cases this trust was regained over time following government and public health responses, however some people remained hesitant about vaccinating their children. Many VSPs were overwhelmed by consultations, workload and psychological pressure after the CCVI. Conclusion: After an initial decline, vaccine confidence recovered to pre-incident levels six months after the CCVI. However, some caregivers moved from the higher to the lower end of the vaccine confidence spectrum, pointing to the need to promote the acceptance of vaccination especially given the need for new vaccines to control the coronavirus epidemic.Cervical screening : ESGO-EFC position paper of the European Society of Gynaecologic Oncology (ESGO) and the European Federation of Colposcopy (EFC)
AbstractKyrgiou, M., Arbyn, M., Bergeron, C., Bosch, F. X., Dillner, J., Jit, M., Kim, J., Poljak, M., Nieminen, P., Sasieni, P., Kesic, V., Cuzick, J., & Gultekin, M. (n.d.).Publication year
2020Journal title
British Journal of CancerVolume
123Issue
4Page(s)
510-517AbstractThis paper summarises the position of ESGO and EFC on cervical screening based on existing guidelines and opinions of a team of lead experts. HPV test is replacing cytology as this offers greater protection against cervical cancer and allows longer screening intervals. Only a dozen of HPV tests are considered as clinically validated for screening. The lower specificity of HPV test dictates the use of triage tests that can select women for colposcopy. Reflex cytology is currently the only well validated triage test; HPV genotyping and p16 immunostaining may be used in the future, although methylation assays and viral load also look promising. A summary of quality assurance benchmarks is provided, and the importance to audit the screening histories of women who developed cancer is noted as a key objective. HPV-based screening is more cost-effective than cytology or cotesting. HPV-based screening should continue in the post-vaccination era. Only a fraction of the female population is vaccinated, and this varies across countries. A major challenge will be to personalise screening frequency according to vaccination status. Still the most important factor for successful prevention by screening is high population coverage and organised screening. Screening with self-sampling to reach under-screened women is promising.Changing travel patterns in China during the early stages of the COVID-19 pandemic
AbstractLSHTM CMMID COVID-19 Working Group, A., Gibbs, H., Liu, Y., Pearson, C. A., Jarvis, C. I., Grundy, C., Quilty, B. J., Diamond, C., Simons, D., Gimma, A., Leclerc, Q. J., Auzenbergs, M., Lowe, R., O’Reilly, K., Quaife, M., Hellewell, J., Knight, G. M., Jombart, T., Klepac, P., … Eggo, R. M. (n.d.).Publication year
2020Journal title
Nature communicationsVolume
11Issue
1AbstractUnderstanding changes in human mobility in the early stages of the COVID-19 pandemic is crucial for assessing the impacts of travel restrictions designed to reduce disease spread. Here, relying on data from mainland China, we investigate the spatio-temporal characteristics of human mobility between 1st January and 1st March 2020, and discuss their public health implications. An outbound travel surge from Wuhan before travel restrictions were implemented was also observed across China due to the Lunar New Year, indicating that holiday travel may have played a larger role in mobility changes compared to impending travel restrictions. Holiday travel also shifted healthcare pressure related to COVID-19 towards locations with lower healthcare capacity. Network analyses showed no sign of major changes in the transportation network after Lunar New Year. Changes observed were temporary and did not lead to structural reorganisation of the transportation network during the study period.Cost-effectiveness of bivalent versus monovalent vaccines against hand, foot and mouth disease
AbstractJit, M., Liu, D., Leung, K., Jit, M., Yu, H., Yang, J., Liao, Q., Liu, F., Zheng, Y., & Wu, J. T. (n.d.).Publication year
2020Journal title
Clinical Microbiology and InfectionVolume
26Issue
3Page(s)
373-380AbstractObjectives: Enterovirus 71 (EV71) and coxsackievirus A16 (CA16) were responsible for 43.3% (235 123/543 243) and 24.8% (134 607/543 243) of all laboratory-confirmed hand, foot and mouth disease (HFMD) cases during 2010–2015 in China. Three monovalent EV71 vaccines have been licensed in China while bivalent EV71/CA16 vaccines are under development. A comparative cost-effectiveness analysis of bivalent EV71/CA16 versus monovalent EV71 vaccination would be useful for informing the additional value of bivalent HFMD vaccines in China. Methods: We used a static model parameterized with the national HFMD surveillance data during 2010–2013, virological HFMD surveillance records from all 31 provinces in mainland China during 2010–2013 and caregiver survey data of costs and health quality of life during 2012–2013. We estimated the threshold vaccine cost (TVC), defined as the maximum additional cost that could be paid for a cost-effective bivalent EV71/CA16 vaccine over a monovalent EV71 vaccine, as the outcome. The base case analysis was performed from a societal perspective. Several sensitivity analyses were conducted by varying assumptions governing HFMD risk, costs, discounting and vaccine efficacy. Results: In the base case, choosing the bivalent EV71/CA16 over monovalent EV71 vaccination would be cost-effective only if the additional cost of the bivalent EV71/CA16 compared with the monovalent EV71 vaccine is less than €4.7 (95% CI 4.2–5.2). Compared with the TVC in the base case, TVC increased by up to €8.9 if all the test-negative cases were CA16-HFMD; decreased by €1.1 with an annual discount rate of 6% and exclusion of the productivity loss; and increased by €0.14 and €0.3 with every 1% increase in bivalent vaccine efficacy against CA16-HFMD and differential vaccine efficacy against EV71-HFMD, respectively. Conclusions: Bivalent EV71/CA16 vaccines can be cost-effective compared with monovalent EV71 vaccines, if suitably priced. Our study provides further evidence for determining the optimal use of HFMD vaccines in routine paediatric vaccination programme in China.Cost-effectiveness of introducing national seasonal influenza vaccination for adults aged 60 years and above in mainland China : A modelling analysis
AbstractYang, J., Atkins, K. E., Feng, L., Baguelin, M., Wu, P., Yan, H., Lau, E. H., Wu, J. T., Liu, Y., Cowling, B. J., Jit, M., & Yu, H. (n.d.).Publication year
2020Journal title
BMC MedicineVolume
18Issue
1AbstractBackground: China has an aging population with an increasing number of adults aged ≥ 60 years. Influenza causes a heavy disease burden in older adults, but can be alleviated by vaccination. We assessed the cost-effectiveness of a potential government-funded seasonal influenza vaccination program in older adults in China. Methods: We characterized the health and economic impact of a fully funded influenza vaccination program for older adults using China-specific influenza disease burden, and related cost data, etc. Using a decision tree model, we calculated the incremental costs per quality-adjusted life year (QALY) gained of vaccination from the societal perspective, at a willingness-to-pay threshold equivalent to GDP per capita (US$8840). Moreover, we estimated the threshold vaccination costs, under which the fully funded vaccination program is cost-effective using GDP per capita as the willingness-to-pay threshold. Results: Compared to current self-paid vaccination, a fully funded vaccination program is expected to prevent 19,812 (95% uncertainty interval, 7150-35,783) influenza-like-illness outpatient consultations per year, 9418 (3386-17,068) severe acute respiratory infection hospitalizations per year, and 8800 (5300-11,667) respiratory excess deaths due to influenza per year, and gain 70,212 (42,106-93,635) QALYs per year. Nationally, the incremental costs per QALY gained of the vaccination program is US$4832 (3460-8307), with a 98% probability of being cost-effective. The threshold vaccination cost is US$10.19 (6.08-13.65). However, variations exist between geographical regions, with Northeast and Central China having lower probabilities of cost-effectiveness. Conclusions: Our results support the implementation of a government fully funded older adult vaccination program in China. The regional analysis provides results across settings that may be relevant to other countries with similar disease burden and economic status, especially for low- and middle-income countries where such analysis is limited.Early dynamics of transmission and control of COVID-19 : a mathematical modelling study
AbstractCentre for Mathematical Modelling of Infectious Diseases COVID-19 Working Group, A., Kucharski, A. J., Russell, T. W., Diamond, C., Liu, Y., Edmunds, J., Funk, S., Eggo, R. M., Sun, F., Jit, M., Munday, J. D., Davies, N., Gimma, A., van Zandvoort, K., Gibbs, H., Hellewell, J., Jarvis, C. I., Clifford, S., Quilty, B. J., … Flasche, S. (n.d.).Publication year
2020Journal title
The Lancet Infectious DiseasesVolume
20Issue
5Page(s)
553-558AbstractBackground: An outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to 95 333 confirmed cases as of March 5, 2020. Understanding the early transmission dynamics of the infection and evaluating the effectiveness of control measures is crucial for assessing the potential for sustained transmission to occur in new areas. Combining a mathematical model of severe SARS-CoV-2 transmission with four datasets from within and outside Wuhan, we estimated how transmission in Wuhan varied between December, 2019, and February, 2020. We used these estimates to assess the potential for sustained human-to-human transmission to occur in locations outside Wuhan if cases were introduced. Methods: We combined a stochastic transmission model with data on cases of coronavirus disease 2019 (COVID-19) in Wuhan and international cases that originated in Wuhan to estimate how transmission had varied over time during January, 2020, and February, 2020. Based on these estimates, we then calculated the probability that newly introduced cases might generate outbreaks in other areas. To estimate the early dynamics of transmission in Wuhan, we fitted a stochastic transmission dynamic model to multiple publicly available datasets on cases in Wuhan and internationally exported cases from Wuhan. The four datasets we fitted to were: daily number of new internationally exported cases (or lack thereof), by date of onset, as of Jan 26, 2020; daily number of new cases in Wuhan with no market exposure, by date of onset, between Dec 1, 2019, and Jan 1, 2020; daily number of new cases in China, by date of onset, between Dec 29, 2019, and Jan 23, 2020; and proportion of infected passengers on evacuation flights between Jan 29, 2020, and Feb 4, 2020. We used an additional two datasets for comparison with model outputs: daily number of new exported cases from Wuhan (or lack thereof) in countries with high connectivity to Wuhan (ie, top 20 most at-risk countries), by date of confirmation, as of Feb 10, 2020; and data on new confirmed cases reported in Wuhan between Jan 16, 2020, and Feb 11, 2020. Findings: We estimated that the median daily reproduction number (Rt) in Wuhan declined from 2·35 (95% CI 1·15–4·77) 1 week before travel restrictions were introduced on Jan 23, 2020, to 1·05 (0·41–2·39) 1 week after. Based on our estimates of Rt, assuming SARS-like variation, we calculated that in locations with similar transmission potential to Wuhan in early January, once there are at least four independently introduced cases, there is a more than 50% chance the infection will establish within that population. Interpretation: Our results show that COVID-19 transmission probably declined in Wuhan during late January, 2020, coinciding with the introduction of travel control measures. As more cases arrive in international locations with similar transmission potential to Wuhan before these control measures, it is likely many chains of transmission will fail to establish initially, but might lead to new outbreaks eventually. Funding: Wellcome Trust, Health Data Research UK, Bill & Melinda Gates Foundation, and National Institute for Health Research.Effect of pediatric influenza vaccination on antibiotic resistance, England and Wales
AbstractChae, C., Davies, N. G., Jit, M., & Atkins, K. E. (n.d.).Publication year
2020Journal title
Emerging Infectious DiseasesVolume
26Issue
1Page(s)
138-142AbstractVaccines against viral infections have been proposed to reduce prescribing of antibiotics and thereby help control resistant bacterial infections. However, by combining published data sources, we predict that pediatric live attenuated influenza vaccination in England and Wales will not substantially reduce antibiotic consumption or adverse health outcomes associated with antibiotic resistance.Effectiveness of isolation, testing, contact tracing, and physical distancing on reducing transmission of SARS-CoV-2 in different settings : a mathematical modelling study
AbstractCMMID COVID-19 Working Group, A., Kucharski, A. J., Klepac, P., Conlan, A. J., Kissler, S. M., Tang, M. L., Fry, H., Gog, J. R., Edmunds, W. J., Emery, J. C., Medley, G., Munday, J. D., Russell, T. W., Leclerc, Q. J., Diamond, C., Procter, S. R., Gimma, A., Sun, F. Y., Gibbs, H. P., … Davies, N. G. (n.d.).Publication year
2020Journal title
The Lancet Infectious DiseasesVolume
20Issue
10Page(s)
1151-1160AbstractBackground: The isolation of symptomatic cases and tracing of contacts has been used as an early COVID-19 containment measure in many countries, with additional physical distancing measures also introduced as outbreaks have grown. To maintain control of infection while also reducing disruption to populations, there is a need to understand what combination of measures—including novel digital tracing approaches and less intensive physical distancing—might be required to reduce transmission. We aimed to estimate the reduction in transmission under different control measures across settings and how many contacts would be quarantined per day in different strategies for a given level of symptomatic case incidence. Methods: For this mathematical modelling study, we used a model of individual-level transmission stratified by setting (household, work, school, or other) based on BBC Pandemic data from 40 162 UK participants. We simulated the effect of a range of different testing, isolation, tracing, and physical distancing scenarios. Under optimistic but plausible assumptions, we estimated reduction in the effective reproduction number and the number of contacts that would be newly quarantined each day under different strategies. Results: We estimated that combined isolation and tracing strategies would reduce transmission more than mass testing or self-isolation alone: mean transmission reduction of 2% for mass random testing of 5% of the population each week, 29% for self-isolation alone of symptomatic cases within the household, 35% for self-isolation alone outside the household, 37% for self-isolation plus household quarantine, 64% for self-isolation and household quarantine with the addition of manual contact tracing of all contacts, 57% with the addition of manual tracing of acquaintances only, and 47% with the addition of app-based tracing only. If limits were placed on gatherings outside of home, school, or work, then manual contact tracing of acquaintances alone could have an effect on transmission reduction similar to that of detailed contact tracing. In a scenario where 1000 new symptomatic cases that met the definition to trigger contact tracing occurred per day, we estimated that, in most contact tracing strategies, 15 000–41 000 contacts would be newly quarantined each day. Interpretation: Consistent with previous modelling studies and country-specific COVID-19 responses to date, our analysis estimated that a high proportion of cases would need to self-isolate and a high proportion of their contacts to be successfully traced to ensure an effective reproduction number lower than 1 in the absence of other measures. If combined with moderate physical distancing measures, self-isolation and contact tracing would be more likely to achieve control of severe acute respiratory syndrome coronavirus 2 transmission. Funding: Wellcome Trust, UK Engineering and Physical Sciences Research Council, European Commission, Royal Society, Medical Research Council.