According to the study published Wednesday in the New England Journal of Medicine, among the 417 Rockefeller University employees who were completely vaccinated with Pfizer or Moderna shots, two of them, approximately 5.5%, had advanced infections. .
“We have characterized good faith examples of vaccine advancement that manifest as clinical symptoms,” the researchers wrote in their study. “These observations do not in any way undermine the importance of urgent efforts at the federal and state levels to vaccinate the U.S. population. They also support efforts to advance a new vaccine booster (as well as a vaccine). against coronavirus) to provide greater protection against variants. “
Researchers at Rockefeller University found that coronavirus variants with several differences from the original virus caused advanced infections.
One variant that infected one of the patients had the E484K mutation, which was first found in variant B.1.351 originally identified in South Africa. E484K has been called an “escape mutant” because it has been shown to escape some antibodies produced by coronavirus vaccines. One of the mutations found in the infections of the two study participants included D614G, which emerged early in the pandemic.
One of the advanced infections was in a 51-year-old healthy woman who received her second dose of the Modern vaccine on February 19th. Nineteen days later, he tested positive for Covid-19 on March 10 after developing symptoms.
The other advanced infection was in a 65-year-old healthy woman who received her second dose of the Pfizer vaccine on Feb. 9. It was later learned that his partner, who was not vaccinated, tested positive for Covid-19 on 3 March. in the following days, the woman developed her own symptoms. On March 17 it tested positive for Covid-19.
More research is needed to determine whether similar findings related to advanced or variant infections will emerge among a larger group of participants from various parts of the United States.
Experts say some advanced cases of Covid-19 are expected in people who have been completely vaccinated, as no vaccine is 100% effective.
The CDC said there were advanced cases in people of all ages who had been vaccinated, but just over 40% were in people 60 or older. They were also more common in women and 29% were asymptomatic.
The agency said it has developed a national database of Covid-19 advances so that state health departments can report them.
“Infections from vaccine advances make up a small percentage of people who are fully vaccinated. The CDC recommends that all eligible people get a COVID-19 vaccine as soon as they are available,” the CDC said in a statement to CNN.
CNN’s Ben Tinker and Maggie Fox contributed to this report.