SARS-CoV-2 is a virus that is transmitted through droplets of our breath, by proximity between people, or by touching surfaces where these droplets may fall. Like all other viruses, this one has also evolved. The main mechanism for its evolution is the acquisition of mutations, which occur when the virus spreads in the cells of an infected individual. These mutant viruses can be transmitted to another individual, leading to an increase in the number of mutations over time, and to the determination of chains of infection. The analysis of the genomes sequenced so far indicates an accumulation rate of 26 mutations per year. In Portugal the average number of mutations observed is 8, given the approximately 150 genomes sequenced to date (https://insaflu.insa.pt/covid19/).