More than 70 percent of coronavirus cases in Israel came from the U.S., according to a study released Monday by Tel Aviv University.
Researchers mapped the spread of the virus by decoding genomic sequences of virus strains in determining that the majority of Israel’s cases originated in the U.S., Adi Stern of the School of Molecular Cell Biology and Biotechnology at the university told The Jerusalem Post.
The researchers used about 4,700 sequences taken globally to compare local patient sequences.
The study, published on medRxiv.org, found the remaining infections in Israel came from Europe and elsewhere, including 8 percent from Belgium, 6 percent from France, 5 percent from England and 3 percent from Spain. The researchers concluded that all infections came from abroad.
Israel did not shut down travel from the U.S. and most visitors from abroad until March 9, while flights from Europe and other areas of the world shut down between Feb. 26 and March 4.
“There was this gap in policy, and this gap allowed people to return from the US who thought that they could go wherever they wanted, so they probably spread the virus that way,” Stern told the Post.
Some infections originating from Europe and Southeast Asia also entered the country, but those patients were quarantined early, limiting the coronavirus’s spread, the Post reported.
The researchers determined that between 1 percent and 10 percent of patients spread about 80 percent of cases at “super-spreading events, such as large parties or other social gatherings.” But the study determined that social distancing efforts did reduce the amount of spread.
Before the study, health officials depended on patient feedback in order to track the spread.
Tel Aviv University was assisted by 11 other health institutes or universities, including Emory University, in the study.
Israel has confirmed 16,643 cases in the country, leading to at least 276 deaths, according to data from Johns Hopkins University.