Swiss bio mathematician Tanja Stadler, who completed the study, found that the virus was imported to Switzerland from a variety of locations.
The researchers collected 1000 DNA samples from positive coronavirus tests, with the number eventually whittled down to 120 samples – many of which had diverse genome sequences.
‘No single Swiss outbreak’
Studies into samples from coronavirus-infected patients has shown that there were several outbreaks of the virus in Switzerland, i.e. that it did not come primarily from one source.
In an online lecture on Tuesday, Sadler said “there was no single Swiss outbreak”.
“The viruses were imported into Switzerland from a wide variety of locations – and there is also no evidence of infections in individual cantons.”
The study looked at the genome sequences of the samples of the virus, finding there was a significant amount of diversity.
The testing process has been done as a part of the Next Strain project, which looks to assess the evolution of Covid-19 in the population.
In addition to understanding aspects of the spread of the virus, the project allows researchers to see how it has changed and evolved over time – for example to become more infectious.
The research also indicates that the virus is likely to have been circulating in Switzerland for days or even weeks before the first case was detected in the southern canton of Ticino on February 25th.