Israel may have reached herd immunity against the SARS-CoV-2 virus, say experts from its largest hospital, Sheba Medical Center.
Herd immunity occurs when a sufficient percentage of a population has immunity—through vaccination or having recovered from the disease—to indirectly protect those who aren’t immune by preventing the disease from spreading.
The immunity level needed to achieve this is calculated based on the transmission rate of the virus in question. For SARS-CoV-2 it’s estimated at 65 to 70 percent, according to Dr. Eyal Leshem, director of Sheba’s Institute for Travel & Tropical Medicine.
Approximately 56 percent of Israel’s 9.2 million citizens are now vaccinated and another 15 percent (approximately 700,000 people) have 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,” said Leshem.
“Compared with the last two lockdowns, after which we saw an increase in cases, we see a decline even after lockdown,” he emphasized.
Could emerging variants of the virus affect Israel’s presumed herd immunity?
“We don’t know yet,” said Leshem. “From what we know, the Pfizer vaccine is quite effective against different variants in prevention of disease and prevention of infection, though it may be slightly less effective against the South African variant, at least in the lab.”
Currently, Israel’s borders are closed to non-citizens except for first-degree relatives of citizens.
When general tourism resumes, said Leshem, “Israel is expected to be a very safe place for travelers because of our lower risk of transmission. The [U.S. Centers for Disease Control] and other public health agencies think that for fully vaccinated people travel is a very low-risk, especially if they have a PCR test before boarding the plane.”
Resuming travel with precautions is “a reasonable risk-benefit balance, provided people are vaccinated or get tested before and after travel and maintain quarantine,” he said.
The real challenge, said Leshem, is children and unvaccinated adults. (The vaccine has only been administered to people 16 and older. Vaccinations in the 12 to 15 age range are to begin in a few months in Israel, following Pfizer clinical studies in that population.)
“There are no magic tricks here,” said Leshem. “If unvaccinated people travel without full quarantine and testing, we will increase the risk of reintroducing the disease to Israel.”