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.
Bibliographical noteFunding Information: This research is funded by an MRC/DFID African Research Leader Fellowship (MR/S005293/1: IMOA, CNM, RC, and AS). IMOA and JAGS have received grants from the Gavi, the Vaccine Alliance. JA GS is funded by a Wellcome Trust Senior Research Fellowship (214320) and the NIHR Health Protection Research Unit in Immunisation. DJN is funded by the Department of International Development and Wellcome [220985/z/20/z]. We thank Dr. Laura Hammitt, Ms. Angela Karani, the residents of the Kilifi Health and Demographic Surveillance System, and the dedicated team of fieldworkers, administrative staff, clinicians, and laboratory staff who worked on this study. We acknowledge the continued collaboration of colleagues and the leadership in the Kilifi County Department of Health. This report is published with the permission of the Director of the Kenya Medical Research Institute.
This research was partly funded by the Bill & Melinda Gates Foundation (INV-003174: MJ). BMGF (OPP1157270: KA). This project has received funding from the European Union’s Horizon 2020 research and innovation programme - project EpiPose (101003688: MJ). This research was partly funded by the National Institute for Health Research (NIHR) using UK aid from the UK Government to support global health research. The views expressed in this publication are those of the author(s) and not necessarily those of the NIHR or the UK Department of Health and Social Care (16/137/109: MJ; NIHR200929: MJ; NIHR Global Health Research Unit on Mucosal Pathogens: JO). Wellcome Trust (208812/Z/17/Z: SFlasche; 210758/Z/18/Z: SFunk).
The following authors were part of the Centre for Mathematical Modelling of Infectious Disease 2019-nCoV working group. Each contributed in processing, cleaning, and interpretation of data, interpreted findings, contributed to the manuscript, and approved the work for publication: James D Munday, Carl A B Pearson, Simon R Procter, Oliver Brady, David Simons, Rachel Lowe, W John Edmunds, Katharine Sherratt, Rosanna C Barnard, Alicia Rosello, Adam J Kucharski, Fiona Yueqian Sun, Nikos I Bosse, Petra Klepac, Yang Liu, Kiesha Prem, Gwenan M Knight, Akira Endo, Sam Abbott, Emily S Nightingale, Thibaut Jombart, Jon C Emery, Georgia R Gore-Langton, Joel Hellewell, James W Rudge, Hamish P Gibbs, Kathleen O’Reilly, Kevin van Zandvoort, Yung-Wai Desmond Chan, Damien C Tully, Anna M Foss, Christopher I Jarvis, Katherine E. Atkins, Samuel Clifford, Matthew Quaife, Billy J Quilty, Rein M G J Houben, Rosalind M Eggo, Graham Medley, Sophie R Meakin, Timothy W Russell, Nicholas G. Davies, Charlie Diamond, Arminder K Deol, C Julian Villabona-Arenas, Stéphane Hué, Megan Auzenbergs, Quentin J Leclerc, Amy Gimma.
The following funding sources are acknowledged as providing funding for the working group authors. Alan Turing Institute (AE). BBSRC LIDP (BB/M009513/1: DS). This research was partly funded by the Bill & Melinda Gates Foundation (INV-001754: MQ; INV-003174: KP, YL; NTD Modelling Consortium OPP1184344: CABP, GFM; OPP1180644: SRP; OPP1183986: ESN; OPP1191821: KO’R, MA). DFID/Wellcome Trust (Epidemic Preparedness Coronavirus research programme 221303/Z/20/Z: CABP, KvZ). DTRA (HDTRA1-18-1-0051: JWR). Elrha R2HC/UK DFID/Wellcome Trust/This research was partly funded by the National Institute for Health Research (NIHR) using UK aid from the UK Government to support global health research. The views expressed in this publication are those of the author(s) and not necessarily those of the NIHR or the UK Department of Health and Social Care (KvZ). ERC Starting Grant (#757699: JCE, MQ, RMGJH). This project has received funding from the European Union’s Horizon 2020 research and innovation programme - project EpiPose (101003688: KP, PK, RCB, WJE, YL). This research was partly funded by the Global Challenges Research Fund (GCRF) project ‘RECAP’ managed through RCUK and ESRC (ES/P010873/1: AG, CIJ, TJ). HDR UK (MR/S003975/1: RME). Nakajima Foundation (AE). NIHR (16/136/46: BJQ; 16/137/109: BJQ, CD, FYS, YL; Health Protection Research Unit for Immunisation NIHR200929: NGD; Health Protection Research Unit for Modelling Methodology HPRU-2012-10096: TJ; PR-OD-1017-20002: AR, WJE). Royal Society (Dorothy Hodgkin Fellowship: RL; RP\EA\180004: PK). UK DHSC/UK Aid/NIHR (ITCRZ 03010: HPG). UK MRC (LID DTP MR/N013638/1: GRGL, QJL; MC_PC_19065: AG, NGD, RME, SC, TJ, WJE, YL; MR/P014658/1: GMK). The authors of this research receive funding from UK Public Health Rapid Support Team funded by the United Kingdom Department of Health and Social Care (TJ). Wellcome Trust (206250/Z/17/Z: AJK, TWR; 206471/Z/17/Z: OJB; 208812/Z/17/Z: SC; 210758/Z/18/Z: JDM, JH, KS, NIB, SA, SRM). No funding (AKD, AMF, CJVA, DCT, KEA, SH, YWDC).
The United Kingdom’s Medical Research Council and the Department for International Development.
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Citation: Mburu, C.N., Ojal, J., Chebet, R. et al. The importance of supplementary immunisation activities to prevent measles outbreaks during the COVID-19 pandemic in Kenya. BMC Med 19, 35 (2021).
- Supplementary immunisation activities
- Vaccination coverage