"The British strain of coronavirus has been circulating in this country without contact with other countries." This was announced by Prof. Nelly Korsun, head of the National Laboratory for Influenza and Acute Respiratory Diseases at the National Center for Infectious and Parasitic Diseases. In an interview with BNR, she said that only one of the carriers of this strain identified through the samples had returned from abroad. Professor Korsun pointed out that no cases of the South African and Brazilian mutations have been registered so far and that there were 33 confirmed cases of the British variant of the virus in Bulgaria.