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Latest Recommendations on COVID-19 Boosters

Although COVID-19 vaccines remain effective in preventing severe disease, recent data suggest their effectiveness at preventing mild infection and possibly severe disease wanes over time, especially in people ages 65 years and older, according to the Centers for Disease Control and Prevention (CDC).

Because our primary care doctors in Delray Beach have received a number of questions about booster doses, we thought we’d bring you up to date on what we know now.

Vaccine effectiveness

First, we want to remind people that the vaccines don’t act like a shield to totally prevent infection with the coronavirus. SARS-CoV-2 is primarily an airborne pathogen that lingers in the air like cigarette smoke in poorly ventilated indoor spaces. Therefore, if you are in such a place unmasked, chances are high that the coronavirus will get into your body.

But the vaccines teach the body to fight off the infection once it’s in you. It works much the same as a seat belt in a car, which doesn’t keep you from getting into an accident, but can keep you from serious injury. This is why some people still get so-called “breakthrough” infections following vaccination.

While the current vaccines—two doses of the Pfizer or Moderna vaccines or one dose of the Johnson and Johnson vaccine—have been found to offer substantial protection from hospitalization and death against all variants of the SARS-CoV-2 coronavirus, their effectiveness against mild to moderate illness tends to wane as time goes by, much like a worn-out seat belt. This was especially true when the super-contagious omicron variant emerged last winter.

Boosting is better

Therefore, the CDC began recommending a booster dose of the vaccine for all adults as well as adolescents from ages 12-17. (Those in that age group can only receive a Pfizer vaccine). A study published this month in the New England Journal of Medicine appears to show that this was good advice.

The study of more than a million people in the U.K. found that the Pfizer vaccine’s effectiveness against experiencing any symptoms at all from infection fell from about 65 percent to about eight percent after six months. The first two Moderna vaccines’ protection against symptomatic illness dropped from about 71 percent immediately after the shots to about 15 percent six months later.

But researchers found that a booster with either vaccine restored protection against mild symptoms back to the original levels. They also noted that the first series of either vaccine even before the booster still offered strong protection against severe disease, hospitalization, and death.

Other studies have seen similar results for the Johnson & Johnson vaccine. One December study of healthcare workers in South Africa found that for those who had received the single-dose Johnson & Johnson vaccine, a booster raised their level of protection from hospitalization from 63 percent to 85 percent.

Boosters forever?

Does this mean we’ll need to keep getting boosters every six months or every year? It’s still too early to say, because we don’t know what the virus will do next. But several new studies suggest the answer may be no.

These studies indicate that the original series plus a booster may provide protection against serious illness and death for months or even years.

“We’re starting to see now diminishing returns on the number of additional doses,” John Wherry, director of the Institute for Immunology at the University of Pennsylvania, told the New York Times last month.

The most recent study, from the Fred Hutchinson Cancer Research Center in Seattle, found that a booster dose produced a wider variety of antibodies that allowed the body to evade most variants of the virus.

“If people are exposed to another variant like omicron, they’ve now got some extra ammunition to fight it,” Julie McElrath, an infectious disease physician and immunologist at Fred Hutchinson, told the Times.

One study published in the journal Nature, in fact, found that the immune T cells can remember how to fight the virus for months or even years. This was similar to studies following the 2003 outbreak of the SARS virus in Asia. Researchers there found that T-cell memory against the virus lasted more than 17 years, the paper reported.

Boosters for high-risk individuals

Still, the World Health Organization (WHO) recommended this month that those at high risk receive a booster dose. This was a new stance from the WHO, which previously was more concerned that everyone around the world could receive the initial series. The organization worried that a focus on boosters for those already vaccinated could lead to vaccine shortages worldwide.

WHO’s statement on March 8 urged booster shots “particularly for groups at risk of developing severe disease, given that current COVID-19 vaccines continue to provide high levels of protection against severe disease and death, even in the context of the circulation of omicron.”

This includes those over age 65 and those who are immunocompromised in some way.

Here’s the latest advice from the CDC:

“The definition of ‘fully vaccinated’ has not changed and does not include the booster shot. Everyone is still considered fully vaccinated two weeks after their second dose in a two-shot series, such as the Pfizer-BioNTech or Moderna vaccines, or two weeks after a single dose vaccine, such as the J&J/Janssen vaccine.

“Fully vaccinated, however, is not the same as optimally protected. To be optimally protected, a person needs to get a booster shot when and if eligible.”

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