A third dose of the Pfizer-BioNTech Covid-19 vaccine has been found to be 86% effective in preventing infection among those ages 60 and up, a new study by one of Israel’s top healthcare providers shows, as the Biden administration prepares to rollout booster shots for Americans next month.
Initial study results published Wednesday by Maccabi Health Services found 37 people out of 149,144, or 0.02%, who received three doses of the Pfizer vaccine have tested positive for Covid-19, compared to 1,064 of the 675,630 people, or nearly 0.2%, who only received a second dose in January or February.
Maccabi, one of Israel’s four top healthcare providers, said it ensured the two groups had similar demographics and found the third doses were 86% effective after at least one week.
The researchers did not specify the severity of breakthrough infections among those receiving a third dose, but the figure marks a stark improvement from Israeli health ministry data, which researchers caution has a wide margin of error, indicating a second Pfizer dose administered in January offers about 55% protection against severe illness for those over the age of 65.
Pfizer has yet to release results on the efficacy of a third vaccine dose, but CEO Albert Bourla says the third, or booster, dose elicits antibody levels that “significantly exceed” those seen in people who received a second dose within six to 12 months.
“The triple dose is the solution to curbing the current infection outbreak,” Dr. Anat Ekka Zohar, who led the Maccabi study, said of the recent outbreak in Israel, which last month became one of the first nations to authorize booster shots for people ages 60 and over.
In a statement Wednesday morning, U.S. health officials announced plans to offer Covid-19 booster shots beginning the week of September 20 to Americans who received a second dose of Pfizer or Moderna’s vaccines at least eight months prior.
Experts and pharmaceutical companies all believe it is likely vaccine recipients will need a booster dose to bolster flagging immunity at some point, though the extent of a second dose’s lasting efficacy is still unclear. Pfizer reports its two-dose vaccine efficacy falls from 96% to 84% after six months, and says results from clinical trials evaluating the safety, tolerability, and efficacy of a third dose are “expected shortly.” Meanwhile, U.S. health officials have grown increasingly concerned about the waning efficacy of vaccines given growing data from Israel and other countries that started inoculating their populations before the U.S. “Although right now, it is still as if our vaccine protection is working really well, we don’t want to wait until it’s too late, so that’s why we’re looking at the data,” NIH Director Dr. Francis Collins said Tuesday.
What We Don’t Know
Officials have yet to make a decision on whether a second dose of the one-dose Johnson & Johnson vaccine should be recommended.
“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,” CDC Director Dr. Rochelle Walensky, White House chief medical advisor Dr. Anthony Fauci and other U.S. health officials said in a Wednesday statement.
168.9 million. That’s how many Americans, about 51% of the population, that have been fully vaccinated against Covid-19.