A journalist questioned Dr. Jay Butler, deputy director for infectious diseases at the Centers for Disease Control and Prevention (CDC) and Dr. Andrew Pavia, pediatric infectious diseases specialist at University of Utah School of Medicine, over potential safety concerns behind a third dose, noting some fully vaccinated people have sought out booster shots on their own.
“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,” Butler told a virtual briefing. He reiterated data suggesting local reactions and rare side effects occur more frequently after the second dose in two-dose regimens.
While several drug manufacturers have developed booster dose strategies involving variant-specific jabs, and have theorized that boosters could become necessary as soon as September, federal health authorities last week said fully vaccinated Americans “do not need” an extra dose at this time.
Pavia said several ongoing studies by the National Institutes of Health are assessing a third dose in a mix-and-match approach (or administering vaccines from different manufacturers) and also by the same manufacturer.
“We’ll get those answers fairly soon we hope,” he said.
Scientists have not yet found evidence of waning immunity or declining levels of antibodies in fully vaccinated individuals, they reiterated, and questions remain whether boosters are necessary, when, and for whom. Ongoing work by the FDA and a panel of independent experts advising the CDC look to provide answers. Butler said researchers are concerned about older adults above age 75 who face the highest risk of severe COVID-19, and those with weakened immune systems, or immunocompromised individuals, some of whom don’t respond as well to vaccination.