Cohort and Matched-Cohort Studies

Observational analyses estimate vaccine effectiveness.

There are several studies of vaccine effectiveness in England and Scotland. There have also been analyses of the vaccine roll-out in Israel.

Despite having similar names, vaccine effectiveness is a different concept to efficacy.

Vaccine efficacy is about reductions in disease. A trial compares vaccinated volunteers to a control group. The trial places people into groups at random. Researchers estimate how well the vaccine does at…