Sep 2, 2021 - Health

Israeli coronavirus vaccine booster data gives the U.S. hope

Illustration of an Israel flag made with syringes for the top and bottom cars

Illustration: Annelise Capossela/Axios

Preliminary Israeli data shows that coronavirus booster shots quickly spike a person's protection against both severe disease and infection, suggesting that the additional shots could help blunt the virus' spread in the U.S. — although it's very unclear how much.

Why it matters: The Biden administration has said that the main rationale for its booster push is to stay ahead of any waning of the vaccines' effectiveness against severe disease. But slowing the spread of the Delta variant would be a welcome bonus.

Driving the news: A preprint study recently released by Israeli researchers found that, in the real world, adults who received a third Pfizer shot saw their risk of confirmed infection drop by 11.4-fold after 12 days or more, and their risk of severe disease drop by more than 10-fold.

  • Israel was the first nation in the world to offer booster shots to its population, beginning with older adults.
  • The study included more than a million people who were 60 or older, and the authors argue that it "demonstrates the effectiveness of a third vaccine dose in both reducing transmission and severe disease."
  • More data is needed to confirm the study's results, which have not yet been peer-reviewed, experts cautioned. One particular limitation of this study is that people who receive a booster may be more risk-averse to begin with.

What they're saying: “The main takeaway message from Israel is there’s a short-term positive effect of boosts on both infection and severe disease," said a senior Biden administration official, adding that the Israeli government recently briefed members of the president's coronavirus team on their data.

  • “I never thought of vaccines as short-term. This changes that paradigm. Again, the jury is out, but Israel is making that case," the official added.

Yes, but: Everyone getting a booster shot is, by definition, vaccinated. The U.S. doesn't have good data on how many cases are occurring among vaccinated Americans, but most cases appear to be among unvaccinated people.

  • Without knowing what contribution the vaccinated are currently making to the spread of the virus or the U.S. caseload, it's impossible to know how much each could be reduced by giving those people a booster shot.
  • Giving a first round of shots to the unvaccinated would be a much more effective way of limiting spread. But ineligible children make up a large chunk of this population, along with vaccine-resistant adults who, thus far, have been unpersuadable.

The bottom line: The U.S. may start offering booster shots to members of the general population in a few weeks. Data like this, despite its limitations, may be our best window — at least for now — into what the effect of the U.S. effort could be.

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