CDC COVID-19 Study Shows mRNA Vaccines Reduce Risk of Infection by 91 Percent for Fully Vaccinated People
The extended CDC HEROES-RECOVER study, enrolling healthcare workers, first responders, frontline workers, and other essential workers shows that mRNA COVID-19 vaccines authorized by the FDA lower the risk of infection by 91% for fully vaccinated people and 81% for partially vaccinated people.
The study is also one of the first to demonstrate that the mRNA vaccine benefits people who get COVID-19 despite full or partial vaccination. 3,975 participants tested themselves for SARS-CoV-2 weekly for 17 weeks, and positive results were then tested for the amount of detectable virus in the nose (i.e., viral load) and the number of days participants tested positive (i.e., viral shedding). Along with a reduced risk of infection, and milder and shorter infection, fully or partially vaccinated people also had 40% lower viral load and lower viral shedding by 6 days, as well as a 66% lower likelihood to test positive for SARS-CoV-2 for over one week compared to those who were unvaccinated. This could relate to a reduced likelihood for vaccinated people to spread the virus to others.
“Findings from the extended timeframe of this study add to accumulating evidence that mRNA COVID-19 vaccines are effective and should prevent most infections — but that full vaccinated people who still get COVID-19 are likely to have a milder, shorter illness and appear to be less likely to spread the virus to others. These benefits are another important reason to get vaccinated,” said CDC Director Rochelle P. Walensky, MD, MPH.
The study findings support CDC’s recommendation to get fully vaccinated, and CDC continues to assess the efficacy of FDA-authorized COVID-19 vaccines in different settings and different groups of people.