Health officials need more information on whether COVID-19 booster vaccines would increase the risk of serious side effects, a Centers for Disease Control and Prevention (CDC) official said on Tuesday.
Deputy Director for Infectious Diseases Jay Butler told reporters that current data shows the risk of developing both rare and common side effects after the COVID-19 shot was higher after the second dose.
"We're keenly interested in knowing whether or not a third dose may be associated with any higher risk of adverse reactions, particularly some of those more severe – although very rare – side effects," he said during a briefing.
The U.S. has not determined whether it will be offering a third dose to fully vaccinated residents, despite Pfizer and BioNTech announcing last week that they will seek authorization from the Food and Drug Administration to provide a third dose of their vaccine.
Officials say more data is needed. Andrew Pavia, a fellow with the Infectious Diseases Society of America, said the National Institutes of Health has already launched studies on whether a third dose is necessary and safe.
“We’ll get those answers fairly soon, we hope,” Pavia said. “But until we have those answers, we can’t answer [the] very good question: Will side effects be more common?”
The debate over booster shots has ramped up in recent days as Pfizer and BioNTech prepare to ask for FDA authorization and as Israel has begun administering third Pfizer doses to those with weakened immune systems.
WHO Director-General Tedros Adhanom Ghebreyesus spoke out against calls for booster vaccines, saying the priority needs to focus on getting initial doses to vulnerable people in need worldwide first.