COVID-19 Vaccine Effectiveness Studies against Symptomatic and Severe Outcomes during the Omicron Period in Four Countries in the Eastern Mediterranean Region

Vaccines Volume 12, Issue 8, 906

The WHO Regional Office for the Eastern Mediterranean supported a regional study of COVID-19 vaccine effectiveness against different clinical outcomes in four countries between June 2021 and August 2023. Health worker cohort studies were conducted in Egypt and Pakistan, and test-negative design case-control studies in Iran and Jordan among patients with severe acute respiratory infection during the Omicron-dominant period. Effectiveness against hospitalisation for a complete primary series was modest, and estimates for individual products, booster doses and secondary outcomes were inconclusive. The study illustrates the design and analysis challenges of conducting vaccine effectiveness studies late in a pandemic, and the country capacities built in the process.