Atlanta, GA–A new CDC study finds the mRNA COVID-19 vaccines authorized by the Food and Drug Administration (Pfizer-BioNTech and Moderna) reduce the risk of infection by 91 percent for fully vaccinated people. This adds to the growing body of real-world evidence of their effectiveness.
Importantly, this study also is among the first to show that mRNA vaccination benefits people who get COVID-19 despite being fully vaccinated (14 or more days after dose 2) or partially vaccinated (14 or more days after dose 1 to 13 days after dose 2).
The findings come from four weeks of additional data collected in CDC’s HEROES-RECOVER study of health care workers, first responders, frontline workers, and other essential workers. These groups are more likely to be exposed to the virus that causes COVID-19 because of their occupations. Preliminary results from this study were first announced in March 2021.
Other study findings suggest that fully or partially vaccinated people who got COVID-19 might be less likely to spread the virus to others. For example, fully or partially vaccinated study participants had 40 percent less detectable virus in their nose (i.e., a lower viral load), and the virus was detected for six fewer days (i.e., viral shedding) compared to those who were unvaccinated when infected.
In addition, people who were partially or fully vaccinated were 66 percent less likely to test positive for SARS-CoV-2 infection for more than one week compared to those who were unvaccinated. While these indicators are not a direct measure of a person’s ability to spread the virus, they have been correlated with reduced spread of other viruses, such as varicella and influenza.