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With the Delta Variant, Do I Need a Covid Booster Shot?

With the #coronavirus #DeltaVariant, Do I Need a #COVID19 Booster Shot?

Although studies of a third dose are underway, experts agree that the vaccines are still working well, even against the Delta variant, and that booster shots are not necessary right now.

Covid-19 booster shots are in the news, but chances are that Americans won’t be getting an extra shot in the arm any time soon.

A surprise announcement from the vaccine maker Pfizer-BioNTech that it plans to seek authorization for a booster shot in the United States has prompted new worries among the general public about the effectiveness of Covid vaccines against the highly contagious Delta variant.

Pfizer said it plans to seek authorization for a booster shot in the coming weeks, citing the possibility that protection against the coronavirus will wane six to 12 months after full immunization with the current two-shot regimen.

But Pfizer’s talk of booster shots has been dismissed as premature by some of the world’s leading vaccine experts, who note that all evidence suggests that the Pfizer shots, along with the Moderna and Johnson & Johnson vaccines, continue to provide strong protection against Covid-19.

A joint statement by the Centers for Disease Control and Prevention and the Food and Drug Administration offered a quick rebuke to the Pfizer announcement, noting that public health officials, not private pharmaceutical companies, would make the decision about booster shots.

“Americans who have been fully vaccinated do not need a booster shot at this time,” the statement said. “We are prepared for booster doses if and when the science demonstrates that they are needed.”

Even so, searches on Google for booster shots surged amid continuing worries about the Delta variant and the risk of breakthrough infections among the vaccinated. Adding to the confusion is the news that Israel’s Ministry of Health said on Monday it would begin offering a third dose of the Pfizer vaccine to adults with weakened immune systems, including cancer and organ transplant patients, in the country’s first step toward booster shots for the most vulnerable.

So is a booster shot in your future? We talked to leading experts about whether booster shots are imminent and why it may be risky to give extra doses to the fully vaccinated in wealthy countries when many people around the world haven’t gotten their first shots. Here are answers to common questions.

Why is Pfizer talking about booster shots?

All of the vaccine companies have been studying booster shots for months, just in case they’re needed in the future. But Pfizer’s announcement that it’s ready to seek approval came as a surprise.

In a news release, Pfizer-BioNTech cited recent data from Israel’s Ministry of Health announcing that although the vaccine remains about 93 percent effective at preventing serious illness and hospitalization, the vaccine is about 64 percent effective at stopping breakthrough infections, or infections that occur in those who are fully vaccinated, with or without symptoms. That figure is down from about 95 percent in May, before the highly infectious Delta variant became widespread.

Experts say the data from Israel hasn’t been peer-reviewed and may be complicated by a number of variables. Other studies from Britain, Scotland and Canada show the Pfizer vaccine is still about 80 percent to 88 percent effective against the Delta variant.

But Pfizer said that the findings from Israel were consistent with its own vaccine studies, and that it planned to present its data to federal health officials. A booster given six months after the second dose of the vaccine increases the potency of antibodies against the original coronavirus and the Beta variant, the form first detected in South Africa, by five- to tenfold, the company said, and it believes a vaccine booster would perform similarly against the Delta variant.

“We continue to believe that it is likely, based on the totality of the data we have to date, that a third dose may be needed within six to 12 months after full vaccination,” the company said.

What do public health experts say about booster shots?

Several public health experts have criticized the Pfizer announcement, calling it “opportunistic” and “irresponsible.” Pfizer’s chief scientific officer met with top U.S. scientists on Monday to discuss the research. Officials said after the meeting that more data — and possibly several more months — would be needed before regulators could determine whether booster shots were necessary.

“Pfizer doesn’t get to decide when we need boosters; the F.D.A., C.D.C. and other regulatory agencies do that,” said Dr. Carlos del Rio, an infectious disease expert at Emory University. “The data needs to be shown publicly in an open, transparent way.”

Dr. del Rio noted that even the data from Israel, cited in the company’s news release, shows the vaccine remains highly effective at protecting people from serious illness. Instead of talking about boosters, the focus should be on getting more shots in the arms of the unvaccinated, he said.

“If you’ve been vaccinated, you don’t need to worry about boosters,” Dr. del Rio said. “The people who need to worry are those that haven’t been vaccinated. The booster is to get more people vaccinated. The more people we get vaccinated, the less likely we’ll have transmission.”

Dr. Paul A. Offit, a professor at the University of Pennsylvania and a member of the F.D.A.’s vaccine advisory panel, said that while it’s important to study the safety and effectiveness of a booster dose to prepare for when it might be needed, the current evidence shows the vaccines are working against the Delta and other variants. He said he thinks it’s unlikely that people in the general population will get booster shots this year.

“All the data to date point to the fact that immunity against severe critical illness is relatively long lasting,” Dr. Offit said. “The issue is not whether we can get a third dose. It’s whether we can get the first two doses in people who aren’t vaccinated.”

Should I be worried about the Delta variant?

The Delta variant now accounts for more than half of all infections in the United States, and the real risks are to the unvaccinated. While the Pfizer vaccine and others in use in the United States are slightly less effective against the Delta variant, all of them still offer significant protection against serious illness or hospitalization from Covid-19.

Moderna has said test-tube studies using blood samples from vaccinated people show the vaccine is still highly effective against the Delta variant, which caused only a “modest reduction” in virus-fighting antibodies in the samples. And Johnson & Johnson has released two studies that show its vaccine remains effective against Delta, showing only a small drop in potency.

“Roughly 99 percent of people who are hospitalized and killed by this virus are unvaccinated,” Dr. Offit said. “You’re not really trying to prevent asymptomatic or mild symptoms. You’re trying to keep people out of the hospital and out of the morgue. It’s a goal we’ve met remarkably well.”

Why not just get a third shot to be sure?

Given that large parts of the world still have very low vaccination rates, and vaccine supplies are limited, most public health experts say it’s shortsighted to give additional doses to people in wealthy countries who are fully vaccinated.

In the United States, nearly 50 percent of all residents are fully vaccinated. But in India, only about 5 percent of the population is fully vaccinated. In much of Africa, fewer than 1 percent of people are vaccinated. The concern is that the longer large parts of the world remain unvaccinated, the greater the risk that new, more threatening variants will emerge.

“American lives continue to be at risk if there are large outbreaks elsewhere with more variants being created,” said Dr. Ashish K. Jha, dean of the Brown University School of Public Health. “Even if you take a very narrow lens that you only care about the lives of Americans, there’s still a very compelling argument that a first shot for an Indian person does more good for America than a third shot for an American.”

In a news conference on Monday, the leader of the World Health Organization pushed back against Pfizer’s plan to seek authorization for booster shots. “The priority now must be to vaccinate those who have received no doses and protection,” Tedros Adhanom Ghebreyesus, the W.H.O. director general, said.

Who will be first in line to get booster shots once they are approved?

Some countries are already giving booster doses of vaccine to people with compromised immune systems, including people who have undergone cancer treatment or those who have had organ transplants. Since April, health care providers in France have routinely given a third dose of a two-dose vaccine to people with certain immune conditions. On Monday, Israel also announced it would give a third dose of vaccine to highly vulnerable adults.

In addition, Moderna is gearing up to test a third dose in 120 organ transplant recipients, and Pfizer, which produces some medications that suppress immunity, is planning a study of 180 adults and 180 children with compromised immune systems.

An estimated 5 percent of the U.S. population is considered to be immunocompromised because of health conditions or drug treatments. While it may be months before booster shots are recommended for the general population, if at all, it’s possible federal health officials will approve an extra shot for a select group of vulnerable patients with compromised immune systems.

Dr. Jha said the medical community was waiting for guidance from the C.D.C. and the F.D.A. about whether to give booster doses to people who are immunocompromised and did not develop adequate protection after a standard course of vaccination. “There are some data emerging that a third shot helps those people,” Dr. Jha said. “It really requires the engagement of your specialist. I think most physicians are saying hold. They’d like to see the C.D.C. recommendations on this.”

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