New research comparing Pfizer and Moderna COVID-19 vaccines raises questions about differences in mortality, but independent scientists say Florida's top health official is drawing conclusions the evidence cannot support.
The study, published Nov. 4 in the scientific journal Global Epidemiology, examined mortality during the year following an initial COVID-19 vaccination. Researchers reported that adults receiving Pfizer's vaccine had a 40% higher relative risk of death from any cause compared with matched individuals who received Moderna's vaccine.
But the distinction between an observed statistical association and evidence of vaccine-related harm is central to understanding the findings.
The study did not include an unvaccinated comparison group, did not establish that Pfizer caused deaths and did not determine whether either vaccine increased mortality compared with remaining unvaccinated.
Nevertheless, the findings quickly became the basis for sweeping claims about COVID-19 vaccine safety, highlighting the challenges of communicating complex scientific research in an increasingly polarized public health environment.
