The importance of supplementary immunisation activities to prevent measles outbreaks during the COVID-19 pandemic in Kenya

BMC Medicine

P. G. M. van Gageldonk¹  G. Smits¹  F. R. M. van der Klis¹  M. Jit²  S. Funk²  K. Abbas²  S. Flasche²  R. Chebet³  A. Sigilai³  B. Karia³  J. Tuju³  D. Akech³  J. Ojal⁴  IMO Adetifa⁴  JAG Scott⁴  C. N. Mburu⁴  D. J. Nokes⁵  C. Tabu⁶ 

[1] Department of Immunosurveillance, Centre for Infectious Diseases Control, National Institute of Public Health and the Environment (RIVM), Bilthoven, The Netherlands;Department of Infectious Diseases Epidemiology, London School of Hygiene and Tropical Medicine, London, UK;KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya;KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya;Department of Infectious Diseases Epidemiology, London School of Hygiene and Tropical Medicine, London, UK;KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya;School of Life Sciences and Zeeman Institute for Systems Biology and Infectious Disease Epidemiology Research (SBIDER), University of Warwick, Coventry, UK;National Vaccine and Immunisation Programme, Ministry of Health, Nairobi, Kenya;

关键词: Measles;    Vaccination coverage;    Outbreak;    COVID-19;    Supplementary immunisation activities;   

DOI  :  10.1186/s12916-021-01906-9

来源: Springer

【 摘 要 】

BackgroundThe 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.MethodsCombining 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.ResultsIn 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.ConclusionWhile 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.

【 授权许可】

CC BY