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Has Israel reached herd immunity?

AP Photo/Tsafrir Abayov

The evidence is mounting, enough so that even Israeli scientists are whispering about it. Emphasis on “whispering,” not shouting: No one wants to climb on a stage and pronounce the pandemic over only to have the country suddenly bedeviled by a new wave. There are still millions of Israelis, a full third of the country, who are unvaccinated — children, mostly. All of them could conceivably be infected.

But the data is what it is. And it’s increasingly hard to argue with.

One way to gauge herd immunity is to guesstimate the share of the population that’s been immunized. If it’s true that around 80 percent need protection before COVID starts slowing down, well, there are reasons to believe that Israel is in the ballpark.

Approximately 56% of Israel’s 9.2 million citizens are vaccinated and another 15% (approximately 700,000 people) recovered from Covid-19, putting Israel comfortably in the expected herd immunity range.

“We’re seeing a decline in the number of cases now despite the return to mass gatherings and schools following the third lockdown, because most of the people the infected person will meet are immune by now,” [Dr. Eyal] Leshem tells ISRAEL21c.

“Compared with the last two lockdowns, after which we saw an increase in cases, we see a decline even after lockdown.”

We could quibble with the math there by noting that there must be some overlap between the vaccinated group and the group that previously recovered from COVID. It’s not quite 71 percent of Israelis who have immunity but something less. On the other hand, most unvaccinated residents are children, and children — especially young ones — seem to enjoy a degree of natural immunity themselves. Could 80 percent of the population be effectively immune, then? Seems possible.

Another way to gauge herd immunity is to see if its distinguishing feature is observable in the population. The great benefit of herd immunity is that it helps protect the unimmunized by closing off so many human pathways for the virus to travel that it only very rarely manages to reach and infect a vulnerable person. To see if that’s happening in Israel, we’d want to know whether infection rates are dropping among those who haven’t been immunized and particularly whether the rate at which they’re dropping depends to some degree on the rate at which the people around them are being vaccinated. That study has now been done in Israel. And guess what.

The new research answers the question of whether vaccinated people protect those around them with a resounding “yes.” It looked at medical data from children — who can’t yet receive vaccines — in some 223 Israeli communities, and found that the more widespread vaccination is among local adults, the less likely the kids are to test positive…

The research, which has been posted online, examined the vaccination rate in adults over three-week intervals in relation to COVID test data from local children 35 days later. They found a clear correlation between the extent of the adult vaccination and the extent of the drop in positive results among children’s tests.

“We find that higher vaccination rates were associated with a later lower infection rate among the unvaccinated cohort,” stated the researchers, headed by Tal Patalon of Maccabi and Prof. Roy Kishony of the Technion.

Again, children come with an asterisk because they seem more resistant to infection naturally than adults are. But some kids do get infected and did so in the Israel study — and as more adults around them got the jab, fewer kids ended up contracting the virus. “[W]ith every 20-point increase in adult vaccination rates in a community, the risk of kids there testing positive halves,” the Times of Israel reports. Rochelle Walensky may have exaggerated when she said that vaccinated people don’t carry the virus but this study is powerful evidence that it’s only a mild exaggeration. Vaccinate a bunch of people and transmission drops community-wide, protecting the vulnerable. Herd immunity.

No COVID post is complete with a graph or two so here you go. Here are the world’s best performers in getting their people fully vaccinated. It’s no contest:

At 56.5 percent, the share of Israel’s population that’s been fully vaccinated is more than twice that of second-place Chile. This is what cases per capita look like now:

Israel has just 35 per million people. By comparison, the U.S. has a shade under 200 and is holding steady at that mark, which is probably the result of opposing pressures between increasing vaccinations and increasing spread of the British variant among the large majority of Americans who still haven’t been fully vaccinated.

You may be looking at that last graph and wondering how the UK has managed to reduce cases to almost the same degree Israel has even though only a small share of its population is fully vaccinated. Two reasons. One is that the UK has been in a lockdown for months; Israel has basically fully reopened. The restrictions in Britain are helping to limit transmissions too, not just the vaccine. The other reason is this:

That’s the share of each country’s population that’s been at least *partially* vaccinated. The UK is following a “first doses first” strategy, remember, in which they’re aiming to give every adult their first shot before worrying about giving people their second. The theory is that partial immunity in a great number of people will slow transmission more than full immunity in a smaller number of people will, especially since the mRNA vaccines provide 80 percent protection even after just one dose. That theory seems to be vindicated based on the UK’s results. We won’t have a better sense until they end their lockdown but some doctors there are wondering if they’ve already reached herd immunity as well thanks to their “first doses first” approach and the degree of preexisting natural immunity in the population after several bad waves. Could be!