Vaccine effectiveness and confounding

Factors affect both vaccination status and Covid-19 death rates.

One major question during the pandemic is: how effective are vaccines? Observational studies look at people without vaccines, comparing outcomes to vaccinated people.

Two possible study designs are:

• Prospective cohort: the study follows groups of individuals over time. The study then examines how vaccination affect outcomes (such as Covid-19 deaths).
• Matched control: the study…