The number of cases of a heart inflammation condition in 16-to-24-year-olds was higher than expected after they received their second dose of Pfizer or Moderna’s Covid-19 vaccines, the Centers for Disease Control and Prevention said Thursday, citing preliminary data from its vaccine safety monitor system.
There have been 275 reported cases of myocarditis or pericarditis, which are inflammation conditions involving the heart, in people ages 16 to 24 as of May 31, according to a CDC presentation that was prepared for a Food and Drug Administration advisory panel meeting Thursday.
The FDA’s Vaccines and Related Biological Products Advisory Committee is holding a meeting to discuss the use of Covid-19 vaccines in children as young as 6 months old.
The expected number of cases was between 10 and 102, according to the CDC.
There have been a total of 475 reported cases of myocarditis or pericarditis in people age 30 and younger, according to the CDC. Most patients who were hospitalized, or 81% of them, had full recovery from their systems, the agency said. As of May 31, 15 people remain hospitalized, with three in intensive care.
The majority of cases appear to occur in men and the median time to onset of symptoms is two to three days, according to the CDC.
The CDC’s vaccine safety group said last month it was looking into heart inflammation conditions in a “relatively few” people who received Covid vaccinations.
The cases were predominantly in adolescents and young adults and usually occurred within four days after getting the shot, the CDC said at the time. The condition was seen more often in men and most cases appear to be mild, the agency said, though officials are following up with the patients.
The CDC is coordinating its investigation with the FDA, which last month authorized the Pfizer-BioNTech vaccine for adolescents ages 12 to 15.
“We still don’t know whether this is truly related to the vaccine,” Dr. Peter Marks, the director of the FDA’s Center for Biologics Evaluation and Research, said during a virtual Q&A event on May 27. He added that the “handful” of cases reported have been “very mild, lasting a day or two” and usually happened after a second dose.
This is a developing story. Please check back for updates.