Coronavirus herd immunity? Not in Israel, according to a serological study

Herd immunity is the idea that when a threshold proportion of a population is immune to a certain pathogen this protects even non-immune individuals against the infection by limiting the spread.

By MAAYAN JAFFE-HOFFMAN
People wear masks as they walk through the Nahalat Binyamin art market which was reopened, following a closure of several weeks due to the Coronavirus. June 2, 2020 (photo credit: MIRIAM ALSTER/FLASH90)
People wear masks as they walk through the Nahalat Binyamin art market which was reopened, following a closure of several weeks due to the Coronavirus. June 2, 2020
(photo credit: MIRIAM ALSTER/FLASH90)
Israelis are not immune to the novel coronavirus and therefore must continue to maintain Health Ministry directives, according to Prof. Dan Cohen, a member of Israel’s Epidemic Treatment Team and the head of Tel Aviv University’s School of Public Health.
Cohen helped run the country’s first serological survey to help determine how many Israelis have had SARS-CoV-2 and may have developed antibodies to protect them from contracting the virus again. The results show that only around 2% to 3% of the population has been infected, based on samples from 1,709 people from across the country.
“The goal of the study was to know how far we are from a level of seroprevalence that would suggest we might be close to herd immunity,” Cohen told The Jerusalem Post. “The recommendation is to continue all the measures because we are not immune.”
Herd immunity is the idea that when a threshold proportion of a population is immune to a certain pathogen this protects even non-immune individuals against the infection by limiting the overall spread.  He said for herd immunity, at least 50% of the population needs to have developed antibodies.
Currently, Israel has recorded around 17,000 coronavirus patients. This means that around 200,000 Israelis have actually had the novel virus, a percentage increase that is inline with most international estimates of between 1:8 and 1:10.
Cohen said the study also showed that the virus was most prevalent among people aged 40-60 and among children 11-19. More males were infected with the virus than females.
He said the highest level of virus was found in Jerusalem, among the lowest levels in Haifa, and Tel Aviv was somewhere in the middle.
Cohen said that the Health Ministry will launch its long-awaited serological survey in Bnei Brak this week. He expects that the virus level there will be found to be higher than in other parts of the country.
On Tuesday, the ministry sent a letter to the health funds explaining how the serological testing process will be carried out in the ultra-Orthodox city, which nearly mirrored a description provided to the Post by Ran Sa’ar, CEO of Maccabi Health Services, last month.
First, the ministry will test members of 150 families who have a verified patient – active or recovering. Second, they will sample 750 symptom-free people living in the same apartment building as a verified patient. Finally, they will test around 2,000 random families.
All the people tested will be over the age of seven.
According to the most recent report by the Health Ministry, around 1.4% of Bnei Brak (2,933 people) had tested positive for coronavirus.
Last week, a team of researchers in Amsterdam published a study indicating that herd immunity to SARS-CoV-2 may not ever be possible due to rapid loss of protective immunity.
“An alarmingly short duration of protective immunity to coronaviruses was found,” the team claimed in a paper titled, “Human Coronavirus Reinfection Dynamics: Lessons for SARS-CoV-2.”
“We saw frequent reinfections at 12 months post-infection and substantial reduction in antibody levels as soon as six months post-infection,” they wrote.