In a new survey of the origins of SARS-CoV-2 in returning travelers, three main genetic groups of the virus have been identified. The study shows that the infection is likely to have entered Sweden from a number of different countries.

The test results analyzed show that the three identified genetic groups of SARS-CoV-2 were present among travelers from several different European countries and the United States as early as February and early March.


It is therefore likely that the infection has entered Sweden from several different countries and that it has spread in these countries earlier than previously reported. In addition to the already known import of cases from Italy and Austria, the presence of various genetic groups also shows that infections were likely introduced in the country on a number of occasions.

Our conclusion is that the infection protection in the regions, through isolation and infection tracking, to a large extent prevented the infection from Italy to gain a foothold in Sweden. Instead, the infection came into the country from a number of different countries because the pandemic was then already a fact, says Karin Tegmark Wisell, Head of Department at the Public Health Authority.

This first survey of inheritance indicates that infection directly from Asia has not gained any major hold in Sweden. The mapping of the virus’s genetic mass makes it impossible to draw conclusions about the origin of the infection.

This is the first genetic survey of SARS-CoV-2 in Sweden. It focuses on the genetic groups identified in the diagnosis during the early phase of the pandemic’s spread in Sweden as well as from sentinel surveillance data, a surveillance system where patients with influenza-like symptoms are tested to demonstrate what proportion of these have covid-19.

By analyzing the genetic mass from the genetic sample in tests with SARS-CoV-2 from Swedish cases and comparing these with cases from the rest of the world, the understanding of how covid-19 was introduced in the country can be increased. Continued work will, among other things, analyze the prevalence of infection in Sweden and in different groups.