Scientists from the Universities of Bath and Edinburgh have found that the mutation rate of the COVID-19 virus has become 50% higher.
The SARS-CoV-2 virus was previously thought to mutate about every two weeks. However, a new study refuted this information. The authors note that the previous assessment did not take into account many mutations that occurred but were not sequenced.
Viruses mutate regularly, for example when errors occur in copying genomes during virus replication. Usually, when we talk about natural selection, we think of new mutations that take advantage and spread, such as the alpha and delta variants of COVID-19. This is called positive selection.
But most of the mutations are harmful to the virus and reduce its chances of survival – they are purging mutations or negative selection. These negative mutations do not persist in the patient long enough to be sequenced. Because of this, they are often overlooked when estimating mutation rates.
When predicting these missing mutations, the team concluded that their actual number is at least 50% higher than previously thought.
The authors noted that if a patient has been suffering from COVID-19 for more than a few weeks, then the virus could evolve. It is believed that the alpha variant is the result of the evolution of a virus inside a person.