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

C. N. Mburu*, J. Ojal, R. Chebet, D. Akech, B. Karia, J. Tuju, A. Sigilai, K. Abbas, M. Jit, S. Funk, G. Smits, P. G.M. van Gageldonk, F. R.M. van der Klis, C. Tabu, D. J. Nokes, LSHTM CMMID COVID-19 Working Group, Jag Scott, S. Flasche, Imo Adetifa

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Background: 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.

Original languageEnglish
Article number35
JournalBMC Medicine
Issue number1
Early online date3 Feb 2021
Publication statusE-pub ahead of print - 3 Feb 2021


  • COVID-19
  • Measles
  • Outbreak
  • Supplementary immunisation activities
  • Vaccination coverage


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