Measles resurgence: an outbreak investigation in Chimanimani District, Manicaland Province, Zimbabwe, 2022

Introduction: Measles is a vaccine-preventable disease. Children who are unvaccinated, below 5 years of age, or malnourished are at risk of severe disease. There were five laboratory-confirmed measles IgM-positive cases in the week ending July 17, 2022, in Chimanimani District. We investigated factors associated with contracting measles in Chimanimani District. Methods: We conducted a 1:1 unmatched case-control study. A case was a Chimanimani District resident aged below 15 years who had measles signs and symptoms or tested IgM positive between August 06 and September 06, 2022. Controls were neighbours without measles. Cases were randomly selected. We recruited 126 cases and 126 controls. An interviewer-administered questionnaire and line list were used to obtain data about the outbreak. District vaccination coverage was analysed from annual reports. We conducted bivariate and multivariate analysis. Results: Majority 102 (81.0%) of measles cases were unvaccinated while 58 (46.0%) controls were unvaccinated. Chimanimani District measles vaccination coverage ranged between 70–89% during 2018-2022. Children of caregivers that objected COVID-19 vaccinations were more likely to contract measles [Odds Ratio (OR) 4.80, 95% Confidence Interval (CI) 2.63-8.76)]. Being unvaccinated [Adjusted Odds Ratio (AOR) 4.06, 95% CI (2.21-7.48)], age of child less than five years [AOR 2.25, 95% CI (1.24-4.08)] and belonging to the Apostolic religion [AOR 2.78, 95% CI (1.48-5.19)] were independent risk factors for contracting measles. Conclusion: Measles outbreak occurred due to low vaccination coverage amidst a huge proportion of vaccine objectors, a highly susceptible population, and a lack of herd immunity. To attain and sustain herd immunity, we recommend increasing routine and supplementary vaccination coverage to at least 95%.