Is America nearing herd immunity with COVID-19? That’s what one scientist believes.
Data scientist Mark Last, a professor at Ben-Gurion University of the Negev in Israel, says that New York and California may have already achieved herd immunity, in which enough people have developed immunity that the risk of further community transmission is either eliminated or significantly reduced. Some estimates say that can occur when 60% of the population have been infected, but one recent study said that number may actually be just 43%.
“Professor Last is using what’s known as the SIR Model of Infection Dynamics for his analysis of the coronavirus,” StudyFinds.com reports. “The model labels segments of the population as either ‘S’ for susceptible, ‘I’ for infectious, or ‘R’ for recovered. He says that New York wasn’t far off from herd immunity in June when there was 400,000 confirmed cases. Antibody tests, however, suggested that there may have been six times that many infections (2.4 million).
If his numbers hold up, the state’s reproduction rate at the time would be 1.14. Since then, the state continues to report a consistent decrease in coronavirus cases. Last believes it may be enough of a drop for herd immunity. He calculates similar results for California as well as Israel.
“In California, it appears that herd immunity was reached around July 15 with slightly more than 10% of their population (4.05 million) being infected,” he says in a media release. “This means that their basic reproduction number R0 under current restrictions is only 1.1.
“In Israel, a further lockdown is not necessary if the current restrictions are maintained and there are no unusual spreading events,” Last says. “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 says.
“If there is no unusual outbreak because of the return to school or mass indoor gatherings, then the infection rate will start dropping. 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.”