The few adults who receive a COVID-19 mRNA vaccine but still become infected have a milder, shorter illness and lower viral RNA loads than their unvaccinated peers, finds a real-world US study yesterday in the New England Journal of Medicine.
The journal also features a UK study confirming that the Novavax vaccine offers 90% overall effectiveness and protects against the highly transmissible and potentially more deadly Alpha (B117) SARS-CoV-2 variant.
mRNA vaccines 91% effective after 2 doses
In the first study, a team led by the Centers for Disease Control and Prevention COVID-19 Response Team tested 3,975 coronavirus-naïve healthcare workers, first responders, and other essential workers who received one or two doses of the Pfizer/BioNTech or Moderna mRNA vaccine or were unvaccinated from Dec 14, 2020, to Apr 10, 2021. The study took place in Arizona, Florida, Minnesota, Oregon, Texas, and Utah.