Study: COVID-19 booster shots dramatically reduce infection risk

Seniors who got a third shot were 11.4 times less likely to be diagnosed with COVID-19.

A large COVID-19 booster shot study in Israel suggests that an extra vaccine dose goes a long way toward protecting vaccinated seniors from the coronavirus — and it could expedite efforts to get boosters approved in the U.S. and beyond.

The challenge: The COVID-19 vaccines available in the U.S. are highly effective, but the longer it’s been since you’ve been jabbed, the less protected you are — this is due to a combination of decreasing antibody levels in your body and more potent variants of COVID-19 in the world.

That’s left U.S. health experts debating whether the nation should start offering people an additional vaccine dose six months or so after they’ve been fully vaccinated. 

Because no one has tested the efficacy of COVID-19 booster shots, though, it’s been hard to say whether that additional dose would be worthwhile — or if we’d be better off trying to get those shots to unvaccinated people.

Seniors who got the booster were 10 times less likely to become seriously ill.

COVID-19 booster study: In July, Israel announced it would begin offering booster shots of Pfizer’s COVID-19 vaccine to people with weakened immune systems and seniors who’d been fully vaccinated for at least five months. 

That made it the first nation to officially approve COVID-19 booster shots of a Western vaccine (boosters of Chinese- and Russian-made vaccines had been previously offered to people in other countries).

Now, researchers from Israel’s Ministry of Health and other health institutes have published a study claiming that the booster shots significantly reduced seniors’ chances of catching COVID-19 and severe illness.

The details: The pre-print study included more than 1.1 million people over the age of 60 who’d been fully vaccinated for at least 5 months. 

“Our findings give clear indications of the effectiveness of a booster dose.”

Bar-On et al.

Starting 12 days after receiving a COVID-19 booster shot, a study participant was 11.4 times less likely to be diagnosed with COVID-19 and 10 times less likely to become seriously ill from the virus than someone who’d only received two shots.

“Our findings give clear indications of the effectiveness of a booster dose even against the currently dominant Delta variant,” the researchers wrote in their paper.

Why it matters: The results could play a key role in making boosters available in the U.S.

In August, President Joe Biden announced plans to launch a booster shot campaign on September 20, but the FDA and CDC have yet to approve it, citing a need for more data on boosters’ efficacy. 

Now, Israeli officials say they’ve been asked to present their study data to the FDA on September 17 — and it could provide the evidence U.S. health officials need to authorize boosters stateside.

However, the Israeli study hasn’t been peer-reviewed yet, and it only involved seniors, so we don’t know if other demographics would respond to COVID-19 booster shots the same way. 

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