Guidance for evaluating COVID-19 vaccine effectiveness

Many critical questions remain about the effectiveness of COVID-19 vaccines in real-world settings. Real-world vaccine effectiveness can be impacted by factors such as vaccine transportation and storage, and the proportion of the target population receiving the vaccine. Real-world vaccine effectiveness studies can answer questions about effectiveness by age-group and risk factors for COVID-19 disease, duration of vaccine protection, protection against transmission, relative effectiveness of different kinds of vaccines, and effectiveness of COVID-19 vaccines against SARS-CoV-2 variants of concern.

WHO/Europe has developed guidance to support countries and institutions that are interested in conducting research on COVID-19 vaccine effectiveness through a cohort study of health workers, a priority population for COVID-19 vaccination.

This guidance complements existing WHO Unity Studies, which focus on sero-epidemiological investigations. Evaluations of COVID-19 vaccine effectiveness should be conducted only after site-specific protocols are developed and approved by the relevant local ethical review committees.

Cohort study to measure COVID-19 vaccine effectiveness among health workers in the WHO European Region

Guidance and methodology for a prospective cohort study to evaluate the effectiveness of the COVID-19 vaccine in health workers

Estimating COVID-19 vaccine effectiveness against severe acute respiratory infections (‎SARI)‎ hospitalisations associated with laboratory-confirmed SARS-CoV-2: an evaluation using the test-negative design

Guidance on estimating COVID-19 vaccine effectiveness against laboratory-confirmed SARS-CoV-2 in patients hospitalized with severe acute respiratory infections (‎SARI)‎

WHO Unity Studies