On Aug. 31, Israel registered 11,000 new Covid-19 cases, the highest daily number since the pandemic began. The worrying thing was: That day’s case count beat a record set in mid-January, when only a small proportion of Israel’s population had been vaccinated.
By the end of August, at least 68% of Israelis had received at least one vaccine dose, but even the vaccinated were falling sick enough to need hospitalization. Alarmed, the Israeli government set about administering booster shots, trying to contain a surge in Covid-19 infections driven largely by the Delta variant of the coronavirus.
In its speed and thoroughness, Israel’s vaccination drive was a shining model. But to other governments, Israel’s late-summer spike now presents the frightening prospect that vaccine immunity may wane quicker than expected. Most countries have been slower than Israel in inoculating their populations, so the logical conclusion seems to be that their drop-off in vaccine immunity will follow Israel’s with a similar lag. Israel’s present looms in other countries’ futures. Indeed, said David O’Connor, a professor of pathology at the University of Wisconsin, “I have every reason to believe that the US is already seeing a version of that same spike in cases.”
But O’Connor and other scientists watching closely don’t necessarily believe that Israel’s patterns have to replicate themselves precisely in other countries. Israel’s Covid-19 escalation does offer signs of what will happen elsewhere in the coming months—but not always in ways that we expect.
“The two answers scientists will always give you is: It’s nuanced and we don’t know,” O’Connor said. O’Connor studies Israel’s Covid-19 data closely and thinks that it is of extremely high quality. Nevertheless, he said, “what we’re trying to do is to learn in real time, as the data comes in, what is happening and what is going to happen. Everything is provisional. We have to live with that uncertainty.”
The Delta variant, for example, was detected for the first time in Israel in early July. The two months since haven’t offered nearly enough time or information to make definite conclusions about the kinds of effects the variant is having. “A lot of it is still speculation,” said Uri Shalit, a bioinformatician at the Israel Institute of Technology.
Among the uncertainties the current phase of Covid-19 presents is that of how long the vaccinated remain safe.
When Shalit first heard about waning vaccine immunity, he was skeptical. He’d never heard of a shot that offered protection for mere months. But after looking at data recording antibody levels in the vaccinated, he has come to believe it’s true. “Even between January 2021 and February 2021, you could see a drop-off,” he said. O’Connor pointed to an American study that found that, from January to July, the Pfizer vaccine’s effectiveness against infection dropped to 42%, and the Moderna vaccine’s dropped to 76%.
Both vaccines still remained very effective against hospitalization in July—75% and 81% respectively—and those numbers represented only a slight fall from the time of their administration in January. Covid-19 deaths in Israel are also far lower than their peak in mid-January, and even lower than the peak of the wave last October.
As a result, one of the primary challenges for any government facing a fresh spike will involve clear and emphatic communication. Governments will have to point out that the vaccinated are safer than the unvaccinated—even in a situation like Israel’s. And they will have to explain the simple arithmetic behind why a relatively high proportion of hospitalized patients are vaccinated people: If a society is mostly made up of vaccinated individuals, then even the few people who do need hospital care during a rise in cases will mostly be made up of vaccinated individuals. “A small percentage of a big number is still a big number,” O’Connor said.
Not everyone is even convinced that vaccine immunity has shrunk enough to trigger Israel’s new wave of disease, though. “It is theoretically possible,” said David Dowdy, an epidemiologist at Johns Hopkins University. “For other human coronaviruses, it does look like people’s immunity probably wanes after a few years. But does the Israel data provide strong evidence that that’s what happened? I’d say it doesn’t.” What to make of vaccine immunity will add a further layer of complication to governments that encounter a burst of cases on their watch.
Local differences matter. For instance, Shalit said, “Israel gave its Pfizer shots three weeks apart, and maybe that was a mistake in hindsight.” Perhaps, in other words, vaccine immunity would have lasted longer if the shots had been given further apart. Then, after the vaccination drive was under way, Shalit said, Israel embarked on a summer of few restrictions, and those only loosely enforced. One of his friends in Germany, Shalit said, is asked regularly for vaccination proof every time he visits a restaurant. “I’ve been to so many places here and I haven’t been asked. Big shows, indoor events, all kinds of things.”
Dowdy also offers an explanation grounded in local demographics to replace the one of waning vaccine immunity. The people who got vaccinated first in Israel, he said, tended to be older, wealthier, and better educated. “This is speculative, but it’s possible that those people traveled more internationally or went to large gatherings, and if they brought infection back, it would circulate in their immediate community of others who were vaccinated early,” he said. Then it’ll start to look as if those who got the vaccine first are the ones at highest risk of getting Covid-19, he pointed out—except that the incidence of disease will be a result not of fading vaccines but of age and activity.
For these reasons, Dowdy said, a country like Germany shouldn’t automatically assume that it will arrive at an Israel-like situation in two or three months just because it lagged behind Israel in its vaccination drive by that same quantum of time. “Is it possible that Germany will have another wave? Sure it’s possible,” he said. Another variant could emerge, or Germany’s strictness with restrictions could relax enough to permit new infections. “But it would be wrong to say that the only difference between Israel and Germany is the timing of vaccinations.”
In Israel, as in the US or western Europe, children form a large part of the as-yet-unvaccinated population. In August, the Israeli government predicted that children would make up half of all new Covid cases by the time the school year began on Sep. 1, and it instituted strict testing regimens for schools. When I spoke to Shalit, a child in his daughter’s class had just tested positive, and since his daughter had to quarantine, Shalit’s family couldn’t meet their relatives for the new year holiday.
Until children receive vaccinations, governments will have to make tricky decisions about whether and how to keep schools open amidst new surges. A vaccine for children aged five and above is drawing closer; on Sep. 10, Pfizer announced it would seek regulatory approval for such a vaccine soon. But until it arrives, Covid-19 will affect more children. “The delta variant is much more highly transmissible than was alpha. So, given that, you will see more children likely to get infected,” Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said in mid-August. “A certain percentage of them will require hospitalization.”
Despite the surge in cases, Israel has been unwilling to impose new levels of lockdown to curb the disease. Its new prime minister, Naftali Bennett, had criticized his predecessor Benyamin Netanyahu for earlier lockdowns. If Bennett now resorted to lockdowns himself, he would risk political embarrassment. “The story would become: Netanyahu got us out of the crisis with vaccines and look at you, you’re locking down again, you screwed it up,” Shalit said.
But additionally, the public appetite for strict curbs on freedoms has dwindled. Shalit believes that some restrictions are still relatively easy to impose: “These events hosting 10,000 people or whatever, for instance—I don’t think the political cost of banning them is so high.” The government could also be stricter with its Green Pass system, which allows people into public venues only if they show a negative test result or proof of vaccination. “Why they aren’t doing it isn’t clear at all.”
The political and economic cost of new lockdowns feels even higher in a country like the US. In O’Connor’s town of Madison, just the previous weekend, “80,000 people had crammed into the stadium to see a football game,” he said. He shared his screen on Zoom and pulled up a video of the stands: people seated right next to each other, not a mask in sight.
“These people are probably thinking that they’ve been vaccinated and want to get back to normalcy, and that it’s their decision to do so, not something to be enforced by a public health authority,” O’Connor said. “And I agree with that to a large extent. But you also have kids under 12 not being vaccinated, and high levels of community transmission making schools vulnerable. So it’s a difficult choice to make.”
If new lockdowns are unpalatable and yet a Covid-19 surge has to be controlled, countries that can afford to buy and dispense a round of booster shots will inevitably choose to do so. Israel started its booster campaign in late July, and Western countries like the UK and the US plan to roll out similar vaccine drives as winter nears.
Early results suggest that the booster shots are effective in tamping down infection rates. “If you look at the numbers, the antibody levels after the booster are around three times as high as they are after the second vaccine dose,” O’Connor said. But there have been no peer-reviewed studies to determine how long the booster’s immunity will last; here too, scientists can only speculate. “I’d take an even-money bet that three to six months after the booster, you’ll have a higher level of protection than after second dose,” O’Connor said. “I could be wrong about that, but I’d take the bet.”
But the West’s booster drive will—rightly—feed the debate about whether the world’s finite supply of vaccinations should be used to dispense third shots to the wealthy or first and second shots to the as-yet-unvaccinated. The World Health Organization has called for a moratorium on boosters until at least the end of 2021. This deepening of vaccine iniquity, O’Connor said, “is a very real issue. People in Israel will benefit less from a third vaccine than people who haven’t gotten any vaccine. So the net gain, for the world, is certainly going to be lower.” Whether to administer boosters or not, he said, will become a political choice as well. “I’m just glad I don’t have to make those decisions.”