National Institute of Allergy and Infectious Diseases Director Anthony Fauci said this week during a press briefing for the White House COVID-19 Response Team that "we do not know" if a fourth COVID-19 shot will be needed.

"We do not know at this point, but we are collecting data that hopefully will inform us about that," Fauci said when asked the possibility of more COVID-19 booster shots by a reporter, according to the Washington Examiner.

"I think there's a reasonable chance that the durability for protection following the third dose will be longer than the durability of protection that I just showed in one of my slides," Fauci said. "If that's the case, we may not need to get boosted every six months or so."

But he added that the data could show that additional doses are necessary down the line.

"If so, we will address it," he said. "We will find out the data, we will make it public, and we will act accordingly."

Fauci told Business Insider last week that his mission is to "make it crystal clear that if you have been vaccinated — go get boosted," adding that the booster campaign will "keep people out of the hospital" and "keep people from dying."

He said that "the effect of boost is very, very favorable to preventing people from getting infected."

Insider noted that there is evidence that in rare cases, young men under the age of 30 have an increased risk of heart inflammation after receiving the mRNA vaccines, and Fauci agreed with those who want to wait for more safety data on boosters, saying that it’s important to ensure "that all the safety data indicate that the benefit-risk ratio for younger people" will "still weigh heavily in the form of the benefit." 

He went on to say that for the vast majority of people, the COVID-19 booster shot is a safe and effective way of protecting against the virus.

"We have got to get almost everybody who's gotten the primary vaccination regimen, we've got to get all of them boosted," Fauci said. "Even though, for the most part, the vaccines absent the boost protect quite well — particularly among younger people — against hospitalization."

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