Estimating COVID-19 vaccine effectiveness against severe acute respiratory infections (SARI) hospitalisations associated with laboratory-confirmed SARS-CoV-2

Many critical questions remain about the effectiveness of COVID-19 vaccines in real-world settings. These questions can only be answered in post-introduction vaccine effectiveness studies.This guidance document outlines an approach to leverage existing surveillance systems for Severe Acute Respiratory Infection (SARI) to estimate COVID-19 vaccine effectiveness (VE) in preventing SARI associated with laboratory-confirmed SARS-CoV-2 using existing SARI surveillance systems. The approach uses the test-negative design to evaluate VE; cases are SARI patients who tested positive for SARS-CoV-2, and controls are SARI patients who tested negative for SARS-CoV-2.