SARS-CoV-2, which causes COVID-19 disease, may have become more contagious by mutating. The virus could be adapting to containment measures such as the use of masks and social distancing.
Scientists at the Methodist Hospital in Houston have published a study of more than 5,000 genetic sequences of the coronavirus that reveals the continuous accumulation of mutations, one of which may have made it more contagious, although not more lethal.
Initially, there were different strains of the virus in Houston, but when the city went from a small initial wave in March to a much larger outbreak at the end of June, 99.9% of patients had the virus with a particular mutation on the surface — the D614G. There, the amino acid called aspartic acid (D) was replaced by one called glycine (G) in a region of the genome that encodes the protein at the tip of Sars-CoV-2, which allows the virus to enter cells.
Researchers found that patients with this strain of coronavirus carried more virus particles than other people, meaning they were probably more infectious.
The spread of this contagious strain of the virus may have increased the infection rate in the Houston area, from an average of around 200 new COVID-19 cases per day to more than 2,400. The new report, however, did not find that this mutation made the virus more lethal or caused different symptoms.
Coronaviruses like SARS-CoV-2 are relatively stable because they have a self-correcting mechanism when replicating, but with the transmission so widespread in the United States, the virus has had abundant opportunities to change, potentially with problematic consequences, explains the study author, James Musser from Houston Methodist Hospital.
David Morens, a virologist at the National Institute of Allergy and Infectious Diseases, reviewed the new study and stated that the findings point to a high probability that the virus has become more communicable and that this “may have implications for our ability to control it.” In other words, the virus is responding to barriers such as the use of face masks and social estating, Morens said.
As a general rule, the more genetic diversity a virus has, the more prepared it will be to avoid future treatments and vaccines. So, the scientists conclude, COVID-19 is most likely following the fate of the common flu. It changes regularly, forcing scientists to constantly develop new vaccines to keep it under control.