In mice and hamsters that were modified in such a way that they show human cell characteristics, both virus variants reached similarly high concentrations in the respiratory tract and also produced comparable symptoms, with the animals with the mutant losing slightly more weight. The researchers conclude that the pathogenicity does not increase significantly as a result of the mutation. In an experiment in which infected hamsters were kept in separate cages but in close proximity to uninfected hamsters, the researchers tested the transferability of the variants. Here, too, the D614G variant was superior to the wild type – it was transmitted much faster. While in the mutant six of the eight exposed hamsters were infected on day two, this was not a single one in the wild type. However, in both variants all exposed animals were infected on day four.