CDC study finds vaccinated people have milder disease in rare breakthrough infections

Coronavirus update: Latest Covid-19 vaccine and US reopening news Most adults in the US have received at least one dose of a coronavirus vaccine, and about 66% said in a recent survey that their lives are at least somewhat back to normal. Follow here for the latest. By Melissa Macaya, <a href="/profiles/melissa-mahtani">Melissa Mahtani</a>, Mike Hayes, <a href="/profiles/meg-wagner">Meg Wagner</a> and <a href="/profiles/veronica-rocha">Veronica Rocha</a>, CNN CNN

New data from CDC on effectiveness of Pfizer and Moderna COVID-19 vaccines

People who have been vaccinated against coronavirus are more than 90% protected against infection and, if they do become infected, they have milder disease than unvaccinated people, a new Centers for Disease Control and Prevention study shows.

The ongoing, real-life study also shows even partially vaccinated people are 81% less likely to become infected than unvaccinated people, the CDC team reported.

The study of more than 3,900 health care staff, first responders and other frontline essential workers who have been tested weekly since December showed that so far 5% have tested positive for coronavirus. Only 16 of the 204 people who became infected had been vaccinated.

The findings are reported in an online preprint on the medrxiv site and have not been peer-reviewed or published in a medical journal.

“This adds to the growing body of real-world evidence of their effectiveness,” the CDC said in a statement.

The workers got either Pfizer/BioNTech’s or Moderna’s two-dose coronavirus vaccine and have been testing themselves weekly since December, regardless of whether they have symptoms. That’s the only way to tell if the vaccines prevent asymptomatic infections.

Those who got “breakthrough” infections after one or two doses of vaccine had 40% less virus in their bodies and were 58% less likely to have fever. They spent two fewer days in bed than unvaccinated Covid-19 patients.