If You're Over 60, This Is How Much a Pfizer Booster Protects You, Study Says

A large study found that breakthrough infections were also less likely after a third shot.

The approved COVID-19 vaccines rolled out over the past few months have all been proven to be highly effective in protecting against the virus. But now that months have passed since the first doses were administered, questions over when people would need an additional shot to keep them effective are finally being answered by health experts and officials. Their decisions have been backed up by new research that has found supplemental doses can go a long way in keeping people safe from the virus, including one new study that found a Pfizer booster significantly protects those who are age 60 and older.

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The latest data comes from a large study conducted by Maccabi Health Services in Israel, where third doses of Pfizer have been available to anyone over the age of 60 since late July. A team of researchers compared results from 149,144 people aged 60 or older who received an additional dose at least a week prior with results from 675,630 from the same age group who had only received the original two doses over January and February. Results found that the Pfizer booster was 86 percent effective at protecting against infection and 92 percent effective against severe infection.

The study also found that there were 37 reported breakthrough infections in those who had received the third dose, while 1,064 patients who only had the original two doses reported testing positive. However, the research team didn't include information on the severity of the cases or specify whether the patients in question had medical conditions that might make them more susceptible, Reuters reports.

"These results are highly encouraging," Eran Segal, a computational biologist at the Weizmann Institute of Science and a key adviser to the Israeli government on the pandemic, said in a statement. "They suggest that the third booster may restore the vaccine efficacy to its original levels."

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A previous study released on Aug. 5 also helped shed light on the potential need for Pfizer booster shots for those who are older. Researchers from Leumit Health Services and the Shamir Medical Center Institutional Review Board in Israel studied a group of 33,943 fully vaccinated adults who were given the Pfizer vaccine. They broke the patients into three age groups: 60 or above, between 40 and 59, and between 18 and 39 years old.

After following up for several months and testing patients for breakthrough cases of COVID-19, results found that infections were rare in those who were vaccinated, with only 1.8 percent of patients reporting a breakthrough case. But data showed that the odds of testing positive increased with age, finding that patients who were 60 and older were three times more likely to have a breakthrough infection five months after receiving their two doses of vaccine.

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The Maccabi Health Services study results also come as health officials in the Biden administration announced on Aug. 18 that COVID-19 booster shots would be available to all beginning the week of Sept. 20, just one week after it had approved the use of a third shot in immunocompromised patients. "The available data make very clear that protection against SARS-CoV-2 infection begins to decrease over time following the initial doses of vaccination, and in association with the dominance of the Delta variant, we are starting to see evidence of reduced protection against mild and moderate disease," top health officials said in a joint statement.

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In conjunction with the announcement, the U.S. Centers for Disease Control and Prevention (CDC) also released three studies that it said had informed its decision, including one that found the efficacy rates of the vaccines against COVID-19 infections overall dropped from 75 to 53 percent in a large study of nursing homes. Combined data from the studies fueled arguments from some experts that boosters may not be necessary for all members of the population.

"Those numbers are actually very good," Ellie Murray, an epidemiologist at Boston University, told The New York Times. "The only group that these data would suggest boosters for, to me, is the immunocompromised."

RELATED: If You Got This Vaccine, You May Be More Protected Against Delta.

Zachary Mack
Zach is a freelance writer specializing in beer, wine, food, spirits, and travel. He is based in Manhattan. Read more
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