Mutated coronavirus variants have been found in 20 of Sweden's 21 counties, Swedish Television SVT News reported on Tuesday.

According to the Public Health Agency, 423 cases had been recorded by last week. However, the full extent of the problem is unknown as only a small portion of positive tests is sequenced to distinguish the new COVID-19 strains.

Meanwhile, random checks conducted in four counties in the first week of February revealed that the mutation first discovered in the United Kingdom – which is more contagious – was responsible for 9-20 percent of the infections.

A small number of cases related to the COVID-19 mutation first discovered in South Africa has also been recorded in Sweden, but there are no known infections connected to the mutation first discovered in Brazil.