Immunocompromised participants were much more likely to have received at least four doses of COVID-19 vaccine than their otherwise healthy peers (73% vs 30%).

People with weakened immune systems—most of whom were vaccinated—made up 4% of a random sample of more than 12 million people in England in 2023 yet represented 22% of both COVID-19 hospital admissions and deaths, according to new findings from the INvestigation oF cOvid-19 Risk among iMmunocompromised populations (INFORM) study.