Both neutral and advantageous mutations can become more common as they get passed down to descendant viruses.
The research team from UCL, Cirad and the Université de la Réunion, and the University of Oxford, analyzed a global dataset of virus genomes from 46,723 people with COVID-19, collected up until the end of July 2020.The researchers have so far identified 12,706 mutations in SARS-CoV-2, the virus causing COVID-19.To test if the mutations increase transmission of the virus, the researchers modeled the virus’s evolutionary tree, and analyzed whether a particular mutation was becoming increasingly common within a given branch of the evolutionary tree — that is, testing whether, after a mutation first develops in a virus, descendants of that virus outperform closely-related SARS-CoV-2 viruses without that particular mutation.The researchers found no evidence that any of the common mutations are increasing the virus’s transmissibility.Instead, they found most common mutations are neutral for the virus.
This includes one mutation in the virus spike protein called D614G, which has been widely reported as being a common mutation that may make the virus more transmissible.
The researchers found that most of the common mutations appear to have been induced by the human immune system, rather than being the result of the virus adapting to its novel human host.van Dorp said: “When we analyzed virus genomes sourced from mink, we were amazed to see the same mutation appearing over and again in different mink farms, despite those same mutations having rarely been observed in humans before.”.
The virus may well acquire vaccine-escape mutations in the future, but we’re confident we’ll be able to flag them up promptly, which would allow updating the vaccines in time if required.”.
November 23, 2020November 23, 2020