Dr. Fauci Warns That Vaccinated People "Need to Realize" This Now


Now that we're more than two years into the COVID pandemic, most of us feel like we have steadier footing against the virus than we did in March 2020. For one thing, we've learned so much about how COVID spreads and what we can do to keep ourselves safe. But we've also gotten access to vaccines and boosters, which may not stave off the possibility of contracting COVID entirely, but are still highly effective at preventing the direst outcomes. At the same time, the pandemic is rapidly evolving, and it's not time to let our guards down completely yet. In fact, there are some things that even the most COVID-cautious Americans might not fully grasp.

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In an April 6 appearance on Bloomberg's Balance of Power podcast, top White House COVID advisor Anthony Fauci, MD, spoke with host David Westin about the current state of the pandemic and what to prepare for next. Fauci began by talking about the issue of "background immunity," which refers to the large number of people who have some protection against COVID from vaccination or prior infection, and what that means for the possibility of another surge.

Unfortunately, Fauci explained, there's only so much this immunity can do—because it isn't long-lasting. "One of the things that people need to realize is that [COVID] immunity wanes, so it isn't like measles," he told Westin. "If you measure someone and take a look at their immunity to measles, that lasts a lifetime. The immunity to COVID … is something that wanes over a period of months."

That's especially important to consider as we face the rise of the BA.2 Omicron subvariant. As Fauci noted in his Balance of Power interview, BA.2 already accounts for 75 percent of cases in the U.S. and is even more infectious than the already highly contagious BA.1 Omicron variant. Many virus experts and health officials believe that the country's positive trajectory will soon be thwarted, with former Food & Drug Administration (FDA) commissioner Scott Gottlieb, MD, saying in an April 5 CNBC interview that BA.2 will cause a "national wave" of new COVID cases.

Fauci told Westin—as he has said repeatedly in recent weeks—that "over the next couple of weeks we are gonna see an uptick in cases." How serious that rise is, however, remains "difficult to predict." Background immunity from vaccination and prior infection comes into play by ideally preventing another surge in cases from becoming a surge in hospitalizations and deaths. But it's not yet known how durable that protection will be.

Vaccinated people—and those who have recovered from a COVID infection—could still get sick during the next surge. On a larger scale, waning immunity makes it hard to say how to achieve the sort of herd immunity that would prevent the worst outcomes. Herd immunity refers to the level of immunity within a community that keeps a virus from spreading. "The wild card in this is to be able to predict accurately what level of immunity over time will present us from getting either a large surge or a surge associated with hospitalizations," Fauci told Westin.

In the Balance of Power interview, Fauci said that a "very high percentage of the population" has been vaccinated and/or infected with COVID, with as many as 90 percent of Americans having some level of immunity to the virus. But because of waning immunity, the percentage of Americans who currently have a high level of protection is almost certainly much smaller.

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In a March 31 article for the Oxford Academic Journal of Infectious Diseases, Fauci and his colleagues at the National Institute of Allergy and Infectious Diseases (NIAID) wrote that "classic" herd immunity against COVID "almost certainly is an unattainable goal." That means that all Americans—including those fully vaccinated and boosted—will need to learn to live with the virus as numbers ebb and flow.

Waning COVID immunity does not mean people should panic about the rise of BA.2 cases in the U.S. As Yale Medicine notes, "Studies have shown that people who are fully vaccinated and have gotten boosters have strong protection against hospitalization from both BA.1 and BA.2." And a Feb. 25 article in Nature concluded that those who were infected with the original Omicron variant have substantial protection against the subvariant and are unlikely to become sick from BA.2.

The concern right now is more in looking toward the future. When Westin—who has been boosted and had an Omicron infection—asked Fauci if he needed another booster, Fauci assured him that his protection against the virus should be strong enough that it's "very unlikely" he would need another shot "for the immediate future." Looking toward the fall, however, Fauci said we need to think about "all of us, who will have waning immunity."

"I have not been infected, but I've been vaccinated and boosted, and certainly over a period of months it is very likely that my immune projection will diminish to the point of needing yet again another booster," he said.

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