A genetic study of the coronavirus reveals that most Israeli patients were infected by a virus originating in the US. The study was led by Dr. Adi Stern of the molecular microbiology and biotechnology department in the George S. Wise Faculty of Life Sciences at Tel Aviv University. The research team managed to sequence the genome of the coronavirus diagnosed in Israel. The sequencing enabled the researchers to identify mutations indicating the chains of infection and the path of the virus from overseas to Israel and also within Israel.
According to Dr. Stern, a characteristic of the virus is that it accumulates mutations that do not affect its behavior, but that make it possible to trace the chain of infection from country to country. For example, at the beginning of the pandemic in China, one or two mutations were added. A virus like this with one mutation made its way to Europe and accumulated more mutations, and from there it passed to the US, and so on. The mutations represent a sort of barcode that make it possible to follow the virus's path. The study finds that about 70% of Covid-19 patients in Israel were infected by a virus originating in the US. 26% belong to the infection chain originating in Europe.
Although all genome sequencing identifies China as the starting point, there are no cases in Israel originating directly from China or from other Asian countries. Genome sequencing provides precise data on the migration of the coronavirus within Israel, and adds an important dimension to the epidemiological investigation of Coid-19 cases, which up to now has been based on questioning of carriers and patients - "Where have you been and with whom?"
The model makes it possible to discover the transmission coefficient within frameworks, such as a family, a building, a school, and so on. It also facilitates the tracing of "super-spreaders". For example, in the course of the research identical viruses were discovered in patients from places far apart from each other, such as Tiberias and Jerusalem, indicating the existence of a carrier who travelled from one city to the other. Events that caused mass infection can also be identified.
A further aspect of the research is the development of a complex mathematical-statistical model that processes epidemiological data. The model shows that the transmission coefficient of the virus (the number of other patients that each patient infects) fell substantially in the wake of the lockdown. The model also shows that the coefficient varies widely from one patient to another. It estimates that more than 80% of infections originate in just 10% of patients or less. This means that most infections in Israel are from "super-spreaders".
On the basis of the model and the genome sequencing, it can be estimated that so far not more than 1% of the population of Israel has been infected by the virus, so that the country is very far from herd immunity.
Published by Globes, Israel business news - en.globes.co.il - on May 20, 2020
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