Comparing SARS-CoV-2 infection rate of vaccinated and unvaccinated populations doesn’t reflect the real COVID-19 vaccine effectiveness
Vaccinated and unvaccinated populations may differ in many characteristics, such as age, population size, social behavior or health seeking behavior. These differences must be taken into consideration when comparing the SARS-CoV-2 infection rates between vaccinated and unvaccinated populations. Failure to do so may lead to biased conclusions. Studies accounting for these differences showed that COVID-19 vaccines effectively reduce the risk of getting sick.