People who became infected with Covid-19 after getting a messenger RNA vaccine carried less virus and had shorter cases than unvaccinated people who became infected, a study by government health researchers found.
Sixteen people in the study who got infected, despite taking a Pfizer Inc.
or Moderna Inc.
vaccine, had on average 40% less virus in their nose compared with the 155 unvaccinated people who became sick, according to the study, published online Wednesday in the New England Journal of Medicine.
The vaccinated individuals also had a 66% lower risk of having detectable virus for more than one week, and they had a shorter duration of illness, with about two fewer days spent in bed, the study said.
The findings provide further evidence supporting what health authorities promoting vaccinations have been saying for months: While getting vaccinated can’t prevent all cases, the relative few that develop tend to be milder.
“Even when people get vaccinated and did get infected, they were less likely to have an illness that causes a fever,” said Mark Thompson, an epidemiologist at the U.S. Centers for Disease Control and Prevention who helped lead the study.