Does the healthy vaccinee bias rule them all? Association of COVID-19 vaccination status and all cause mortality from an analysis of data from 2.2 million individual health records

Vaccination against COVID-19 was the key measure in battling the pandemic and its effectiveness against death and severe course has been demonstrated in a multitude of studies. However, a vast majority of these studies (apart from registration studies) were observational. It has been proposed that observational studies are subject to inherent biases, including differences in testing strategies between vaccinated and unvaccinated groups or in determining the cause of death (with COVID vs due to COVID)[1,2].
Source: International Journal of Infectious Diseases - Category: Infectious Diseases Authors: Source Type: research