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Health experts weigh in ahead of CDC's meeting on booster shots

booster shots
Posted at 10:06 AM, Aug 11, 2021
and last updated 2021-08-11 14:00:31-04

CHICAGO — On Friday, the Centers for Disease Control and Prevention (CDC) advisory committee on immunizations will be meeting to discuss a strategy for booster shots. Some countries are already administering third doses due to diminished protection over time. However, the World Health Organization (WHO) says that’s the wrong strategy.

Data shows that over time, the protection from the COVID-19 vaccines weakens. But does it drop low enough to require a booster shot?

“The original strains of the virus show that vaccine immunity starts to wane at maybe about six months or so, but that change is very small,” explained Dr. Michael Angarone, an infectious diseases specialist and associate professor of medicine at Northwestern University’s Feinberg School of Medicine.

At six months, that drop goes from 95% to about 90%. With new variants like delta, the efficacy, says Dr. Michael Angarone, may drop down to 75-80% with the Pfizer vaccine.

The vaccines still prevent severe COVID-19 illness.

“But I think the more interesting factor is that we're not seeing those individuals who've had the vaccine getting the critical illness that we see in unvaccinated individuals,” said Dr. Angarone.

Still, the Food and Drug Administration (FDA) could roll out a plan in the next few weeks to authorize an additional dose of COVID-19 vaccine, specifically for people who are immune-compromised. But recent data from Johns Hopkins suggest it could be an exercise in diminishing returns.

“Giving a third dose does increase the antibody response in some people, but there's still a large percentage of transplant patients who aren't responding to the vaccine even after a third dose,” said Dr. Kawsar Talaat, co-director of clinical research at the Johns Hopkins Institute for Vaccine Safety.

The National Institutes of Health recently began a pilot study to assess the antibody response to a third dose mRNA vaccine in kidney transplant recipients who didn’t respond to two doses of the Moderna or Pfizer vaccine.

“It may even be futile, you know, getting a third shot, getting a fourth shot for the people that are the most vulnerable if they're still high amounts of circulating virus in their communities, they will still be at risk,” said Dr. Sadiya Khan, assistant professor of preventive medicine at Northwestern University Feinberg School of Medicine.

In the U.S., at least 50% of adults are fully vaccinated, with just over 70% having gotten one dose. Some health experts argue we should focus our efforts on vaccinating as many people as possible in the United States and around the world before we start giving booster doses of vaccine.

“Less than 1% of all vaccine doses have gone to low-income countries,” said Dr. Khan. “There are no walls in place. This is what's going to keep circulating.”

“Now, it's time to start thinking about, well, what do we do for the rest of the world to start getting them to the 20%, 30%, 50%, and more, so that we can really get everyone in the world access to these vaccines and get vaccinated?” said Dr. Angarone.

Some experts say moving to boosters before increasing total vaccination numbers could prove ineffective in the long run, potentially extending the pandemic’s potency.

“The boosters will only protect you against the strains that the vaccine is made for," said Dr. Talaat. “But as the virus circulates, you could have mutant strains that have all different variants that evolve that the vaccines won’t protect against.”

It's why reaching the unvaccinated won’t just protect them, but everyone else as well, say the health experts.