Herd immunity occurs when a sufficient percentage of the 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. According to Prof. Eyal Leshem, Director of Sheba’s Institute for Travel & Tropical Medicine, it’s estimated at 65 to 70 percent for COVID-19.
Approximately 54% of Israel’s 9.2 million citizens are now fully vaccinated, and another 15% (approximately 700,000 people) have recovered from COVID-19, putting Israel in the expected herd immunity range.
“We’re seeing a decline in the number of cases despite the return to mass gatherings and schools following the third lockdown because most of the people an infected individual will meet are immune by now,” said Prof. Leshem, who added: “Compared with the last two lockdowns, after which we saw an increase in cases, we see a decline even after the lockdown. However, we don’t know for certain yet if the emerging variants of the virus will affect Israel’s presumed herd immunity. From what we do know, the Pfizer vaccine seems quite effective against different variants in the prevention of disease and 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 Prof. 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.”
The real challenge, explains Prof. Leshem, concerns children, since the vaccine has only been administered to people 16 and older. However, vaccinations in the 12 to 15 age range are to begin in a few months in Israel, following Pfizer clinical studies in that population group.