To boost or not to boost? Breaking down the COVID booster debate.

To boost or not to boost? The question of whether to authorize vaccine boosters is vexing scientists and public health officials as the nation endures the worst phase of the COVID-19 pandemic.

The answer will undoubtedly impact Florida, where 21 percent of the population — more than 4.5 million people — are over 65 and could benefit the most if booster shots are found to be safe and effective.

A panel of experts who advise the Food and Drug Administration voted Friday that current evidence does not support giving Pfizer booster shots to most Americans. But they did agree that boosting people ages 65 and older and those at high-risk of death if infected was warranted. The panel also included those who risk getting infected on the job, like frontline medical workers.

That is not the final say. The FDA is not bound by the vote. The agency and the Centers for Disease Control and Prevention must both decide the booster question.

The Biden administration still hopes this coming week to offer booster shots. But those who received the Moderna and Johnson & Johnson vaccine face a longer wait to find out if scientists will endorse boosters for them.

The debate grabbed national attention last week after a group of 18 scientists, including two FDA officials, published an article arguing there is insufficient evidence to justify booster shots to the general public — that the best strategy to combat the pandemic is to use those doses to vaccinate the unvaccinated in the U.S. and across the world.

Scientific debate usually plays outs behind closed doors and in specialized journals. But the question of COVID boosters is the latest rift in the scientific community to spill out into the public during the pandemic, and the stakes are as high as ever.

The article, published Sept 13 in the medical journal The Lancet, argues no booster is needed because over 90 international studies have shown that “COVID-19 vaccines continue to be effective against severe disease.”

Even if boosters “were eventually shown to decrease the medium-term risk of serious disease,” the authors wrote, “the current vaccine supply could save more lives if used in previously unvaccinated populations.”

But the science is hardly settled, health experts say. The Lancet article did not include recent studies that suggest booster shots can dramatically reduce infection rates, especially for older populations — a view now endorsed by the FDA panel.

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Two studies out of Israel indicate booster shots can greatly decrease the chance of infection or illness, especially for those over 60.

One study published in the New England Journal of Medicine tracked the more than 1.1 million Israeli residents over 60 who received a third shot of the Pfizer vaccine between July 30 and Aug. 22. It found a tenfold reduction in infection and severe illness compared to those who only had two doses.

A second study, still under peer-review, followed 150,000 adults who got an additional shot after Israel authorized boosters to anyone over 30. Those participants saw a 70 to 84 percent reduction in the risk of infection after 14 to 20 days.

The dramatic results may be due to the increased level of antibodies produced by the third shot, said University of Wisconsin epidemiologist David O’Connor. Those who got a booster shot had about three times the number of antibodies as someone who had two doses, according to Pfizer data.

There are reasons to believe a third dose “will actually be durable, and if it is durable, then you’re going to have very likely a three-dose regimen being the routine regimen,” said Dr. Anthony Fauci, the director of the National Institute of Allergy and Infectious Diseases, at a Sept. 1 White House briefing.

The Israeli studies only focused on the Pfizer vaccine. Moderna has also applied for approval of a booster dose of its vaccine after initial study results indicate a 36 percent reduction in protection after 12 months. In August, Johnson & Johnson provided evidence that receiving a second dose of the one-shot vaccine produced a stronger immune effect. U.S. Surgeon General Dr. Vivek Murthy said Aug. 22 that Johnson & Johnson vaccine recipients “likely need a booster.”

Epidemiologists like O’Connor who support booster shots are optimistic that, by reducing infection and illness, a booster strategy could help curb community spread and halt the epidemic.

“Giving more people the boost as soon as possible would interrupt the spread of delta in highly affected communities, and it would likely turn the tide within a few weeks,” he said.

Getting transmission rates down helps protect those who remain vulnerable to the coronavirus, he said. That includes kids under 12 who are ineligible to get vaccinated, the elderly and immunosuppressed, unvaccinated adults, and frontline medical workers exhausted by sustained high hospitalization rates.

If boosting can reduce transmission of the virus, then it can save lives.

“I’m personally uneasy with the idea that we’re just going to roll the dice (and not approve boosters),” O’Connor said.

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Health experts who oppose a universal booster rollout say it is a policy choice as much as a scientific question. Policy makers, they say, must decide how to prioritize scarce vaccine supplies in the face of scientific uncertainty.

Despite the positive initial results, the long-term efficacy of booster shots is still unknown, said University of Florida epidemiologist Ira Longini, who co-authored The Lancet article.

Israel moved ahead with boosting elderly residents in July after preliminary studies found a waning efficacy of the two-part Pfizer vaccine. Data have shown remarkable results from the boosters so far, Longini said, but the Israeli studies measured immune response after a short window. Nor is it clear how durable the immune response will be and whether reducing individual infections will lower community spread.

The FDA panel, however, questioned whether Israel’s data is relevant to the U.S. population and expressed concerns whether the extra dose would exacerbate side-effects.

Booster shots would need to reduce the chance of infection by 90 to 95 percent to truly halt community spread, Longini estimates — and those are not the kind of results he’s seeing.

“If we can get large numbers of people vaccinated, we can certainly reduce infection and transmission,” he said, “but we’re not going to eliminate the virus even at extremely high coverage.”

The current vaccine regimens are still effective at protecting against hospitalization and death, Longini said, so the nation’s primary goal should be to get as many people fully vaccinated as possible.

The CDC recently published new evidence reinforcing the importance of primary vaccination. It analyzed data from 600,000 Americans between April 4 and July 17 and found that unvaccinated individuals were 5 times as likely to become infected with the coronavirus. They were also more than 10 times as likely to be hospitalized and die from COVID-related illness.

In Florida, 39 percent of the total population remains unvaccinated. Those people pose the greatest threat of spreading the virus and straining the health care system if they require hospitalization, experts say.

“Boosters are not some magic bullet that (is) going to save us,” Longini said. “We need to be vaccinating the unvaccinated, not vaccinating the already vaccinated.”

That’s why the experts who spoke to the Tampa Bay Times say they support President Joe Biden’s efforts to close the vaccination gap by requiring 100 million Americans — including federal and private employees and health care workers — to get vaccinated.

“The lack of vaccination is a cancer on our collective productivity when we have high levels of community transmission,” O’Connor said. “We need to be very aggressive in trying to make sure we remove the cancer of this virus.”

• • •

Rolling out universal booster shots has implications beyond the U.S. Vaccine doses used to boost the already-vaccinated could instead help inoculate those in poorer nations that have had limited access, the authors of The Lancet article argued.

The math of vaccine boosters vs. increasing the vaccination rate is simple, said Johnathan Gruber, a Massachusetts Institute of Technology economist who helped design the Affordable Care Act.

“In the U.S., there is no evidence that it would reduce hospitalization by more than about 10 percent, and probably less,” he said. “But if you give that booster shot to someone outside the U.S., you probably lower their chance of hospitalization by about 90 percent.”

If a vial of vaccine does about nine times as much good if you give it as a first shot to someone in India than as a third shot to someone in the U.S., Gruber said the question facing Americans is: “Is a life in the U.S. worth nine times a life in India?”

His answer: “My next move would be to take every unit we’ve got and ship it to India.”

Addressing vaccine equity has as much to do with self-preservation as it does with ethics, Longini said. The delta variant emerged in India before spreading to Britain and the U.S.

To halt the global pandemic, the World Health Organization estimates every country would need to vaccinate 40 percent of its population by the end of 2021, and 70 percent by the first half of 2022. So far, only 61 of the 184 nations tracked by the New York Times have met that first benchmark.

The situation is worse in low-income countries, where less than 1 percent are fully vaccinated, according to an article in the British science journal Nature. Just 10 percent of the population of lower-middle-income countries are vaccinated, the article reported, while on average more than 50 percent are fully vaccinated in high-income countries.

“There’s no reason why these variants won’t keep emerging as long as there is global transmission on the planet,” Longini said. “We are putting America first by slowing the transmission on a global level.”

• • •

While scientists debate the issue, there may be a way forward that public health experts can agree on: the most vulnerable should get the booster shot first.

The CDC and FDA agreed in August that immunocompromised people should receive a third dose of the Pfizer or Moderna vaccine. That means patients undergoing cancer treatment who received an organ transplant or have another immunodeficiency should undergo a three-dose regimen instead of two doses.

Immunocompromised patients who received either the Pfizer or Moderna vaccine can now schedule a third shot at local pharmacies. Florida had administered 277,551 of those additional doses as of Friday.

Older Floridians have borne the brunt of the latest wave of COVID infections, making up approximately a third of hospitalizations and 63 percent of deaths since June 18.

Public health experts who spoke to the Tampa Bay Times unanimously agreed that the FDA panel’s take — expanding booster shots to the elderly, frontline workers and those with pre-existing conditions — is an agreeable compromise.

“We could possibly help protect them a bit better,” Longini said. “If they do get limited use of boosters, it certainly makes sense.”

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