When will we know if booster COVID shots are needed? Fauci estimates a timeline

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Dr. Anthony Fauci says we’ll likely know by this fall whether booster COVID-19 vaccines will be necessary.

The nation’s top infectious disease expert said Sunday on ABC’s “This Week” that the need for another dose of the vaccine depends on “correlate immunity” against the coronavirus.

“When the slope starts coming down you can predict when you’re going to get below the safe level or you could start seeing breakthrough infections,” Fauci said. “I believe by the time we get to the end of the summer and the beginning of the fall, we’ll have a pretty good idea of whether we definitely or not need to give people boosts and when we need to give it to them.”

Fauci’s comments come as drugmakers Pfizer and Moderna have indicated a third dose of their vaccines — both of which currently require two doses to be fully effective — could be necessary.

Research has shown both shots offer more than 90% protection against COVID-19 for at least six months. But it remains unclear how long that protection will last, and vaccine makers are working to determine whether additional doses will be needed as more contagious variants of the coronavirus spread across the United States.

Moderna CEO Stéphane Bancel told CNBC last week that the company hopes to have a booster shot for its vaccine ready by the fall. Previously, Corinne M. Le Goff, Moderna’s chief commercial officer, said during a call with investors that countries that have “achieved high vaccine coverage” should be able to focus on administering booster shots by 2022 or the end of 2021, Business Insider reported.

Last week, Pfizer CEO Albert Bourla said people who received the Pfizer vaccine will “likely” need a third dose sometime after receiving their second.

“A likely scenario is there will be likely a need for a third dose somewhere between six and 12 months, and then from there, there would be an annual revaccination,” Bourla said during a CVS Health livestream. “But all of that needs to be confirmed, and again, the variants will play a key role. It is extremely important to suppress the pool of people that can be susceptible to the virus because they are vaccinated with high-efficacy vaccines.”

Alex Gorsky, CEO of Johnson & Johnson, told CNBC in February that people may need to get vaccinated against COVID-19 annually. The Johnson & Johnson vaccine — which federal health officials called for a pause on after six women developed extremely rare blood clots within two weeks of vaccination — requires just one dose.

These booster shots could help protect against COVID-19 infections among fully vaccinated people, called “breakthrough infections.”

Breakthrough cases are rare and usually mild. The Centers for Disease Control and Prevention told CNN on Thursday that, of the 77 million Americans who have been fully vaccinated, about 5,800 people have contracted the virus. Of those, 396 required hospitalization and 74 died.

Fauci said on NBC’s “Meet the Press” on Sunday that the decision about a booster will be a “public health decision.”

“It’s not going to be a decision that’s going to made by a pharmaceutical company,” he said. “We’re partners with them because they’re supplying it. It’ll be an FDA, CDC decision. The CDC will use their advisory committee and immunization practices the way they always do.”