During the outgoing week British researchers warned that there are more than 4,000 different SARS-CoV-2 strains circulating in the world, and the UK variant, which is much more contagious, is now spreading in Bulgaria. Commenting on the virus mutations for Nova TV, Prof. Soren Hayrabedyan, Director of the Institute of Biology and Immunology of Reproduction of the Bulgarian Academy of Sciences pointed out that the Brazil Covid-19 variant is the most dangerous of all.

“It has 20 mutations and the mortality rate is much higher.” In the words of Prof. Hayrabedyan even immunity acquired individually may not be enough. "In the state where the epidemic is now spreading, at least 50% of the population contracted the disease during the first wave, nevertheless there is a new wave there now," Prof. Soren Hayrabedyan said but added that does not necessarily mean people develop severe forms of the disease.