Megan Redshaw

A new peer-reviewed study shows two doses of an mRNA COVID-19 vaccine yield negative protection against symptomatic SARS-CoV-2 infection, while previous infection without vaccination offers about 50% immunity.

The findings, published June 15 in the New England Journal of Medicine (NEJM) analyzed information from more than 100,000 Omicron-infected and non-infected residents in Qatar from Dec. 23, 2021, through Feb. 21, 2022.

The authors compared the effectiveness of the Pfizer and Moderna COVID-19 vaccines, natural immunity from previous infection with other variants and hybrid immunity (a combination of infection and vaccination) against symptomatic Omicron infection and severe, critical and fatal disease.