Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, speaks during a Senate hearing on Health, Education, Labor and Pensions in the Dirksen Senate office building in Washington, DC, the United States, July 20, 2021.

Stefani Reynolds | Reutesr

White House senior medical advisor Dr. Anthony Fauci said Thursday everyone will “likely” need a booster dose of Covid-19 vaccines one day.

“We are already seeing signs of a reduction in the shelf life of the vaccines,” Fauci told CBS This Morning.

However, he said that it is unlikely that they will be widespread anytime soon. The priority, Fauci said, is to give a booster to people with compromised immune systems, including cancer patients and transplanted organs.

“We don’t feel at this point that we don’t need a booster vaccination right now, apart from the immunocompromised people,” he said.

Fauci’s comments come on the same day the Food and Drug Administration is expected to approve the third Covid vaccination for people with compromised immune systems, a highly anticipated move designed to protect some of the most at-risk Americans from the highly contagious Delta variant.

Such people, including cancer and HIV patients, make up only about 2.7% of the adult US population, but account for about 44% of hospitalized breakthrough Covid cases in which a person is fully vaccinated, according to recent data from a Centers for Disease Advisory Group on Control and Prevention becomes infected.

Studies suggest that a third shot might help people whose immune systems don’t respond as well to a first or second dose.

Covid vaccine makers, including Pfizer and Moderna, have repeatedly argued that everyone will need a booster dose at some point and possibly additional doses each year, just like they did with seasonal flu. Pfizer has announced that it will be asking the FDA to approve boosters as it sees signs of waning immunity.

The US drug maker cited data from Israel, where officials report that the two-dose vaccine is now only 39% effective in the country. The vaccine is still highly effective against serious illness, hospital admissions and deaths, according to Israeli health officials.

The CDC does not currently recommend booster doses of the vaccines for otherwise healthy people. But Fauci, who spoke on NBC’s “TODAY” Thursday, said, “inevitably there will be a time when we need to get boosts.”

“No vaccine, at least not within this category, will offer unlimited protection,” he said.