An evaluation of the measles surveillance system, and descriptive epidemiology of measles in Kenya (2020 – 2021)

Introduction: Measles remains a significant public health concern worldwide, with a global case fatality rate of 3-5%, rising to 10% during epidemics. Infants under one year are most vulnerable, with fatality rates of 20-30%. In Kenya, measles surveillance is conducted through the Integrated Disease Surveillance and Response platform. We evaluated the measles surveillance system to assess its effectiveness and conducted a descriptive epidemiological analysis of measles data to understand the distribution of measles cases in Kenya in 2020 and 2021. Methods: We evaluated attributes of the surveillance system using the United States Centers for Disease Control and Prevention (US-CDC) guidelines for surveillance system evaluation. For the evaluation, we interviewed surveillance, clinical and laboratory staff to assess system attributes using a graded questionnaire. Measles is suspected in persons with fever, rash and either cough, coryza or conjunctivitis. A confirmed case is a suspected measles case that has been investigated and has serological confirmation of recent virus infection (IgM positive) having not received measles vaccination in the 30 days preceding specimen collection. We conducted a descriptive analysis of measles cases in 2020 and 2021. Results: The measles surveillance system is simple, sensitive and stable with a PVP of 9.8%, though data gaps exist. A measles outbreak was declared in May 2020, and a reactive supplementary immunization activity (SIA) held in June 2021. A total of 2077 measles cases were reported, including 188 laboratory-confirmed cases. Garissa County reported the highest number of confirmed cases (44). The annual incidence rate of measles was 1.78 per million in 2020, and 2.03 per million in 2021. Conclusion: The surveillance system is effective, although outbreak response was delayed. Measles appears to be endemic in Kenya, with a rising incidence rate. Recommendations include improved training for surveillance officers and clinicians, data quality audits, timely outbreak responses, and the development of a measles elimination strategy.