Should the definition of ‘fully vaccinated’ include a booster shot?

For many Americans who scrambled to get vaccinated against COVID-19 when it was their turn, the relief of gaining immunity was just a reward. Achieving fully vaccinated status also bestowed a faint Halo of Virtue.

Now both the biological protection of the syringes and the satisfaction of contributing to herd immunity prove short-lived. And with a worrying new variant coronavirus threatening to further undermine vaccine-induced immunity, health officials are debating whether the definition of “fully vaccinated” should be changed to include a booster shot.

Scientists are strongly inclined, and public health leaders are not far behind.

So far, the Centers for Disease Control and Prevention has not officially moved the goalposts. Americans who are subject to occupational immunization requirements or must show proof of “full vaccination” to enter gyms, restaurants, or public events can meet the requirement without a refresher.

But the CDC has tiptoed to those goalposts, telling all but the youngest vaccinated Americans that lasting immunity will require an extra dose, and urging everyone 16 and older to get one as soon as they are eligible.

dr Anthony Fauci, President Biden’s senior adviser on the pandemic, also walked straight towards the line – but did not cross it.

“The best protection comes with a third shot,” Fauci told CNN this week. He added that while the official definition of “fully vaccinated” won’t change this week or next, it will eventually happen: “It’s going to be a question of when, not if.”

The number of fully vaccinated Americans, by the current definition, surpassed 200 million this week, and a quarter of them have received a booster. That leaves millions of Americans with one more to-do item on their list, wondering if they’ll be better off getting one, and wondering if it’ll be the last.

Your confusion is understandable. The vaccines’ early promise of spectacular efficacy has given way to some bleak headlines about faltering immunity. But the CDC has continued to claim that for most healthy Americans, a “full shot” — two shots of Pfizer-BioNTech or Moderna vaccine, or a single Johnson & Johnson shot — provides effective protection from hospitalization or death in patients with ” Breakthrough Infections provides .

Until recently, even independent vaccine experts seemed ambivalent. During September and October, CDC and Food and Drug Administration advisers reviewing the latest evidence were clearly underwhelmed by the argument for recommending booster shots for healthy adults under the age of 65.

They wholeheartedly endorsed the additional vaccinations for older Americans and those with weakened immune systems. However, many were reluctant to conclude that younger adults would benefit from a booster shot, particularly given the risk of heart-related side effects, which mainly affect younger men, and the risk of blood clotting for women under 50.

Their decision to limit access was promptly overruled by the CDC, which recommended booster shots for virtually all adults once six months had passed since their second dose of either mRNA vaccine, or two months since their J&J vaccination.

Now, said Dr. William Schaffner, an infectious disease specialist at Vanderbilt University Medical School, experts who had doubts are dismissing their concerns.

At first it was too confusing to send different messages to different age and professional groups. Additionally, new research has made it increasingly clear that the first two doses of an mRNA vaccine and the single injection of the J&J vaccine behave like a single “prime” dose, requiring a subsequent “boost” dose to be fully effective to unfold.

As with most vaccines, a COVID-19 booster shot is required to boost immunity and make it durable. And there’s precedent for a three-can series, he noted. Widespread vaccines for hepatitis B, polio, and other diseases require three or more shots.

dr Peter Hotez, dean of Baylor College of Medicine’s National School of Tropical Medicine, agreed, “I’ve said from the start that this is a three-dose vaccine.”

Given the urgency that existed when vaccines first became available, it made sense to place the first and second doses of the mRNA vaccine close together, Hotez said. “But based on previous experience with vaccines, we know that this will lead to a drop in immunity. And you will need a third dose some time later.”

By the summer, the rising incidence of breakthrough infections provided growing support for this supposition. Most of the early cases were in elderly and immunocompromised people, who often do not have a strong immune response to vaccines. Many experts hoped that the need for boosters would end there.

But evidence of declining immunity to all vaccines and across the age range is mounting. Even fully vaccinated younger adults with breakthrough infections can become seriously ill and die.

This week brought the first real evidence of the benefits of boosters in young, healthy people. Israeli researchers found that a third dose of Pfizer’s vaccine prevented infections in 16- to 29-year-olds more dramatically than any other age group measured. Given the key role played by young adults in sustaining the spread of a pandemic, some scientists suggested that a policy of universal booster vaccination could do more than reduce hospitalizations and deaths. It could also suppress new waves of infection.

This and another new study from Israel also reinforced the evidence for the powerful benefits of boosters for middle-aged adults. Israelis aged 50 and older who received a third vaccination were 10 times less likely to die from COVID-19 than their vaccinated but unboosted peers. Israelis aged 60 and older reduced their risk of serious illness by a factor of more than 12 compared to their peers who did not receive a third vaccination, and they were almost 15 times less likely to die from COVID-19.

Los Angeles County has provided further evidence of the effect of boosters. In the seven days ending November 29, there were 43 new infections per 100,000 population, who were fully vaccinated but not boosted. But among those who received a booster shot, the rate of new infections was only 7 per 100,000.

Right now, Hotez said, it’s more important to clearly communicate to those over 16 that they should get booster shots for their own protection than to change the definition of “fully vaccinated” — something that’s part of everyday life in cities like Los Angeles and San Francisco, which would require proof of vaccination to enter indoor businesses such as restaurants and gyms.

As health officials grapple with the next step of the pandemic, they may decide that reducing COVID-19 deaths and keeping people out of hospital are the most pressing priorities. This would require a greater focus on increasing rates of primary vaccination versus booster vaccination.

But as case numbers fall, the emphasis on boosters could be a way to slow transmission and end the pandemic sooner — and changing the definition of fully vaccinated might well support such a goal, Hotez said.

Some experts remain skeptical that this move would make sense. They question whether it is ethical and productive to offer extra doses to those least likely to get seriously ill when many of the world’s poorest countries have just started vaccinating their populations.

The new findings from Israel clearly show that booster shots are valuable for people aged 50 and over, said Dr. Emily P. Hyle, infectious disease specialist at Massachusetts General Hospital. But “it’s getting a little harder” to conclude that they’re useful for younger people, she added.

“I’m looking for more detailed data on what kind of symptoms they prevent. Is it a cold day or a week or two of serious illness?” said Hyle. “That would be really helpful to know.”

The answer could spark a broader debate about whether getting more Americans — or the rest of the world — their first doses of the vaccine is a more effective use of scarce resources, she said. That, in turn, should also spark “some tough talks” about the goals US health officials should aim for: eradicate transmission altogether, minimize serious illness and deaths, or return to pre-pandemic life without public health compromises.

Hotez said it’s possible a fourth shot — or more — will be needed. This will depend on a variety of unknowns beyond how the human immune system responds to boosters, including the emergence of variants that undermine vaccine protection, and the priorities of public health officials.

“We don’t know until we know,” he said. Should the definition of ‘fully vaccinated’ include a booster shot?

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