COVID Booster Loses Potency After 4 Months, Fauci Says 'There May Be the Need' for Fourth Dose

Greg Nash-Pool/Getty Images Dr. Anthony Fauci

A fourth dose of the COVID-19 vaccine might be necessary for some Americans.

New data from the Centers for Disease Control and Prevention (CDC) finds that the mRNA shot's protection begins to decline after about four months, according to a study released Friday.

Although vaccine effectiveness against COVID-related hospitalizations was at 91 percent during the first two months after a third dose, it decreased to 78 percent by the fourth month.

The study, which was conducted during the Omicron-dominate phase of the pandemic, focused on those who sought medical treatment for COVID symptoms. It did not include a breakdown of age or whether their third dose was a booster or part of their primary inoculation series, which the CDC recommends for some immunocompromised people.

"There may be the need for yet again another boost — in this case, a fourth-dose boost for an individual receiving the mRNA — that could be based on age, as well as underlying conditions," Dr. Anthony Fauci, the nation's top infectious disease expert, told reporters Tuesday.

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LUIS ACOSTA/AFP via Getty Pfizer-BioNTech's COVID-19 vaccine

Fauci clarified that recommendations for a fourth dose will likely not be made "across the board for everyone," adding: "It very likely will take into account what subset of people have a diminished, or not, protection against the important parameters such as hospitalization."

The CDC's update comes after the COVID-19 death toll in the U.S. surpassed 900,000 last week, less than two months after it reached 800,000. President Joe Biden urged Americans who hadn't gotten their shots yet to get vaccinated as he marked the tragic milestone.

"Vaccines and boosters have proven incredibly effective, and offer the highest level of protection," he said. "Two hundred and fifty million Americans have stepped up to protect themselves, their families, and their communities by getting at least one shot — and we have saved more than one million American lives as a result."

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As of Feb. 11, about 75.8 percent of Americans have received at least one dose of a COVID-19 vaccine, and 64.3 percent are fully vaccinated, according to the CDC's COVID Data Tracker. Just 42.7 percent of fully vaccinated people have gotten a booster dose, for which 50.2 percent are eligible.

A recent report from the Centers for Disease Control showed that unvaccinated people in the U.S. were 53 times more likely to die of COVID-19 compared to those who are vaccinated and boosted.

"We can save even more lives — and spare countless families from the deepest pain imaginable — if everybody does their part," Biden said.

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