Waning of COVID-19 vaccine effectiveness: individual and public health risk

High coverage rates of vaccination against COVID-19 are envisaged to end the pandemic. However, waning of vaccine-induced protection is a growing concern that has been fostered by data on vaccine effectiveness against the currently circulating omicron SARS-CoV-2 variant of concern (VOC). A systematic review and meta-regression by Daniel R Feikin and colleagues in The Lancet provides robust evidence of waning vaccine effectiveness over time. The authors identified 18 studies matching their inclusion criteria, of which three were randomised controlled trials (RCTs). Studies with participants of any age were included in the main analysis, with nine of 18 studies also including adolescents (aged ≥12 years). Information on sex or ethnicity distribution per study was not provided. Evidence from the meta-regression suggested a decrease in protection against SARS-CoV-2 infection by 21·0% (95% CI 13·9–29·8; on the basis of evidence from six studies) over a 6-month period from full vaccination across all ages and for...