Unexposed populations and potential COVID-19 burden in European countries

We estimate the potential remaining COVID-19 burden in 19 European countries by estimating the proportion of each country's population that has acquired immunity to severe disease through infection or vaccination. Our results suggest that many European countries could still face a substantial burden of hospitalisations and deaths, particularly those with lower vaccine coverage, less historical transmission, and/or older populations. Continued non-pharmaceutical interventions and efforts to achieve high vaccine coverage are required in these countries to limit severe COVID-19 outcomes.