Israel has vaccinated at least 25 percent of its population against the coronavirus so far, which leads the world and makes it "the country to watch for herd effects from" the Pfizer-BioNTech COVID-19 vaccine, says infectious disease expert David Fishman. Recently, the case rate in Israel appears to have declined sharply, and while there could be a few reasons for that, it's possible the vaccination effort is beginning to play a role.
One study from Clalit that was published last week reports that 14 days after receiving the first Pfizer-BioNTech shot, infection rates among 200,000 Israelis older than 60 fell 33 percent among those vaccinated compared to 200,000 from the same demographic who hadn't received a jab.
At first glance, Fisman writes, that might seem disappointing since clinical trials suggested the vaccine was more than 90 percent effective. But he actually believes the 33 percent figure is "auspicious." Because vaccinated and non-vaccinated people are mingling, there could be "herd effects of immunization." In other words, when inoculated people interact with people who haven't had their shot, the latter individual may still be protected because the other person is. On a larger scale, that would drive down the number of infections among non-vaccinated people, thus shrinking the gap between the two groups' infection rates.
More data needs to come in, and Fisman thinks "we'll know more" this week, but he's cautiously optimistic about how things are going.