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Effects of adjusting public health, travel, and social measures during the roll-out of COVID-19 vaccination: a modelling study.
Lancet Public Health. 2021 09; 6(9):e674-e682.LP

Abstract

BACKGROUND

Since the emergence of the COVID-19 pandemic in late 2019, various public health and social measures (PHSMs) have been used to suppress and mitigate the spread of SARS-CoV-2. With mass vaccination programmes against COVID-19 being rolled out in many countries in early 2021, we aimed to evaluate to what extent travel restrictions and other PHSMs can be relaxed without exacerbating the local and global spread of COVID-19.

METHODS

We adapted an existing age-structured susceptible-infectious-removed model of SARS-CoV-2 transmission dynamics that can be parameterised with country-specific age demographics and contact patterns to simulate the effect of vaccination and PHSM relaxation on transmission. We varied assumptions by age-specific susceptibility and infectiousness, vaccine uptake, contact patterns, and age structures. We used Hong Kong as a case study and assumed that, before vaccination, the population is completely susceptible to SARS-CoV-2 infection. We applied our model to 304 jurisdictions (27 countries and 277 sub-national administrative regions from eight countries). We assumed that PHSMs have suppressed the effective reproductive number (Re) to fall between 1·0 and 9·0 locally before the commencement of vaccination programmes. We evaluated the levels of PHSMs that should be maintained during the roll-out of COVID-19 vaccination to avoid a large local outbreak of COVID-19, with different assumptions about vaccine efficacy, vaccination coverage, and travel restrictions. We assumed that the maximum capacity of the health system, in terms of daily hospital admissions, is 0·005% of the population size.

FINDINGS

At vaccine efficacy of 0·80 in reducing susceptibility to SARS-CoV-2 infection, 0·50 in reducing SARS-CoV-2 infectivity, and 0·95 in reducing symptomatic COVID-19 diseases, vaccination coverage would have to be 100% for all individuals aged 30 or older to avoid an outbreak, when relaxing PHSMs, that would overload the local health-care system, assuming a pre-vaccination Re of 2·5. Testing and quarantine of at least 5 days would have to be maintained for inbound travellers to minimise the risk of reintroducing a local outbreak until high vaccination coverages are attained locally and overseas in most countries.

INTERPRETATION

Gradual relaxation of PHSMs should be carefully planned during the roll-out of vaccination programmes, and easing of travel restrictions weighed against risk of reintroducing outbreaks, to avoid overwhelming health systems and minimise deaths related to COVID-19.

FUNDING

Health and Medical Research Fund and the General Research Fund.

Authors+Show Affiliations

WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China; Laboratory of Data Discovery for Health, Hong Kong Science Park, Hong Kong Special Administrative Region, China. Electronic address: ksmleung@hku.hk.WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China; Laboratory of Data Discovery for Health, Hong Kong Science Park, Hong Kong Special Administrative Region, China.WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China; Laboratory of Data Discovery for Health, Hong Kong Science Park, Hong Kong Special Administrative Region, China.

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

34388389

Citation

Leung, Kathy, et al. "Effects of Adjusting Public Health, Travel, and Social Measures During the Roll-out of COVID-19 Vaccination: a Modelling Study." The Lancet. Public Health, vol. 6, no. 9, 2021, pp. e674-e682.
Leung K, Wu JT, Leung GM. Effects of adjusting public health, travel, and social measures during the roll-out of COVID-19 vaccination: a modelling study. Lancet Public Health. 2021;6(9):e674-e682.
Leung, K., Wu, J. T., & Leung, G. M. (2021). Effects of adjusting public health, travel, and social measures during the roll-out of COVID-19 vaccination: a modelling study. The Lancet. Public Health, 6(9), e674-e682. https://doi.org/10.1016/S2468-2667(21)00167-5
Leung K, Wu JT, Leung GM. Effects of Adjusting Public Health, Travel, and Social Measures During the Roll-out of COVID-19 Vaccination: a Modelling Study. Lancet Public Health. 2021;6(9):e674-e682. PubMed PMID: 34388389.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Effects of adjusting public health, travel, and social measures during the roll-out of COVID-19 vaccination: a modelling study. AU - Leung,Kathy, AU - Wu,Joseph T, AU - Leung,Gabriel M, Y1 - 2021/08/11/ PY - 2021/04/30/received PY - 2021/06/23/revised PY - 2021/07/12/accepted PY - 2021/8/14/pubmed PY - 2021/9/3/medline PY - 2021/8/13/entrez SP - e674 EP - e682 JF - The Lancet. Public health JO - Lancet Public Health VL - 6 IS - 9 N2 - BACKGROUND: Since the emergence of the COVID-19 pandemic in late 2019, various public health and social measures (PHSMs) have been used to suppress and mitigate the spread of SARS-CoV-2. With mass vaccination programmes against COVID-19 being rolled out in many countries in early 2021, we aimed to evaluate to what extent travel restrictions and other PHSMs can be relaxed without exacerbating the local and global spread of COVID-19. METHODS: We adapted an existing age-structured susceptible-infectious-removed model of SARS-CoV-2 transmission dynamics that can be parameterised with country-specific age demographics and contact patterns to simulate the effect of vaccination and PHSM relaxation on transmission. We varied assumptions by age-specific susceptibility and infectiousness, vaccine uptake, contact patterns, and age structures. We used Hong Kong as a case study and assumed that, before vaccination, the population is completely susceptible to SARS-CoV-2 infection. We applied our model to 304 jurisdictions (27 countries and 277 sub-national administrative regions from eight countries). We assumed that PHSMs have suppressed the effective reproductive number (Re) to fall between 1·0 and 9·0 locally before the commencement of vaccination programmes. We evaluated the levels of PHSMs that should be maintained during the roll-out of COVID-19 vaccination to avoid a large local outbreak of COVID-19, with different assumptions about vaccine efficacy, vaccination coverage, and travel restrictions. We assumed that the maximum capacity of the health system, in terms of daily hospital admissions, is 0·005% of the population size. FINDINGS: At vaccine efficacy of 0·80 in reducing susceptibility to SARS-CoV-2 infection, 0·50 in reducing SARS-CoV-2 infectivity, and 0·95 in reducing symptomatic COVID-19 diseases, vaccination coverage would have to be 100% for all individuals aged 30 or older to avoid an outbreak, when relaxing PHSMs, that would overload the local health-care system, assuming a pre-vaccination Re of 2·5. Testing and quarantine of at least 5 days would have to be maintained for inbound travellers to minimise the risk of reintroducing a local outbreak until high vaccination coverages are attained locally and overseas in most countries. INTERPRETATION: Gradual relaxation of PHSMs should be carefully planned during the roll-out of vaccination programmes, and easing of travel restrictions weighed against risk of reintroducing outbreaks, to avoid overwhelming health systems and minimise deaths related to COVID-19. FUNDING: Health and Medical Research Fund and the General Research Fund. SN - 2468-2667 UR - https://www.unboundmedicine.com/medline/citation/34388389/Effects_of_adjusting_public_health_travel_and_social_measures_during_the_roll_out_of_COVID_19_vaccination:_a_modelling_study_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S2468-2667(21)00167-5 DB - PRIME DP - Unbound Medicine ER -