A new study conducted by Prof. Mark Last of Ben-Gurion University shows that in the next two weeks Israel will have reached a state of herd immunity against the coronavirus.
Herd immunity is a scenario in which the percentage of a population which has already contracted and recovered from a viral disease is so high that the rate of new infections drops as more and more people become immune to the disease, eventually reaching near-zero.
Last said that a further lockdown in Israel is not necessary if the current restrictions are maintained and there is no unusual spreading, due to the opening of the new school year or mass events.
Last has analyzed the available data regarding coronavirus confirmed cases and deaths and concluded that “if we maintain the current restrictions, then my model predicts that we are at the end of this peak, which should tail off at the end of August or the beginning of September.
“Moreover, according to my calculations, we need 1.16 million people with antibodies in order to achieve herd immunity and we are very close to that number,” he said.
“If there is no unusual outbreak because of the return to school or the chagim, then the infection rate will start dropping.”
He noted that “while another lockdown would certainly reduce infection rates, there is no need at the present time since social and physical distancing is working to lower infection rates.”
Last is a member of the Department of Software and Information Systems Engineering at Ben-Gurion University and director of the University’s Data Science Research Center. He has been analyzing health data for the past two decades. He presented his findings at the AIME 2020: International Conference on Artificial Intelligence in Medicine last Wednesday.
Prof. Last’s findings support the steps taken by coronavirus task-force coordinator Prof. Roni Gamzu, who announced a series of possible measures to reduce the spread of the virus in Israel.
He compared Israel’s situation to a number of European countries such as Italy, Greece and Sweden, countries with similar characteristics to Israel.
“Our health system has managed to keep the percentage of deaths from COVID-19 to under 1% out of the total number of confirmed cases. Other countries had rates as high as 16% [Italy] and 14% [Sweden] at the beginning of the epidemic and have recently pushed them to around 3%,” he said.
The outlook for coronavirus patients who reach the ICU in Israel is not so optimistic – about an 80% mortality rate, according to Last’s calculations. The global percentage is currently about 60%, according to the World Health Organization. Last’s previous research, unconnected to coronavirus, showed that the normal mortality rate is close to 20% mortality among those admitted to ICUs.
Prof. Last noted that no country currently has an organized database of the medical history of their coronavirus patients. In Israel, for example, the number of coronavirus patients and mortality rates are released, but there is no accessible database with clinical data at the individual patient level, such as medical history, number of sick days, location of infection, and the like.
Last’s model is based on the coronavirus-attributed deaths reported by the Health Ministry and an estimation of the total number of infected people based on published results of serological tests rather than just on confirmed cases.
There was a discrepancy between his model and the Health Ministry’s reported deaths until the ministry released a correction earlier in the month. Now, his model exactly predicts the death rate.
“We cannot know the actual number of cases of infection unless we test the entire population every day. Initial serological tests indicate the ratio of confirmed cases to actual cases is about 1 to 10. Using those numbers, we now have slightly above one million people with antibodies in Israel and we need at least 1.2 million,” he explained.
Last says he is cautiously optimistic about the coronavirus pandemic in Israel. “We are heading in the right direction, but it is important not to relax our restrictions or get overconfident,” he warned.