The coronavirus is indeed mutating as it spreads around the world, but according to a new study out of University College London’s Genetics Institute, there’s no evidence that the virus is becoming more infectious.
The research, published in Nature Communications, analyzed a massive global dataset of virus genomes from more than 46,000 people with COVID-19 from ninety-nine countries. The researchers eventually were able to identify more than 12,700 mutations in the SARS-CoV-2 virus.
“The number of SARS-CoV-2 genomes being generated for scientific research is staggering. We realized early on in the pandemic that we needed new approaches to analyze enormous amounts of data in close to real time to flag new mutations in the virus that could affect its transmission or symptom severity,” the study’s co-author Lucy van Dorp, a professor at University College London’s Genetics Institute, said in a news release.
“Fortunately, we found that none of these mutations are making COVID-19 spread more rapidly, but we need to remain vigilant and continue monitoring new mutations, particularly as vaccines get rolled out.”
To test if the mutations increase transmission of COVID-19, the researchers modeled the evolutionary tree of the virus and analyzed whether a particular mutation was becoming increasingly common within a given branch of the evolutionary tree. This entails testing whether a particular descendant of the virus outperforms closely related SARS-CoV-2 viruses without that specific mutation.
The team found no evidence that any of the common mutations is increasing the transmissibility of COVID-19. Instead, they discovered that the most common mutations are neutral for the virus, including the mutation in the spike protein called D614G, which reportedly has the potential to make the virus more infectious.
Moreover, the researchers were able to conclude that most of the common mutations appear to have been spurred by the human immune system, rather than the virus adapting to its human host.
“We may well have missed this period of early adaptation of the virus in humans,” lead author Francois Balloux, a professor at the University College London’s Genetics Institute, said in a news release.
“We previously estimated SARS-CoV-2 jumped into humans in October or November 2019, but the first genomes we have date to the very end of December. By that time, viral mutations crucial for the transmissibility in humans may have emerged and become fixed, precluding us from studying them.”
The team fully expects the virus to continue to mutate and eventually diverge into different lineages as it becomes more common in human populations. This, however, does not mean that it will become more transmissible or deadly.
“The virus seems well adapted to transmission among humans, and it may have already reached its fitness optimum in the human host by the time it was identified as a novel virus,” Van Dorp said.
Ethen Kim Lieser is a Minneapolis-based Science and Tech Editor who has held posts at Google, The Korea Herald, Lincoln Journal Star, AsianWeek, and Arirang TV. Follow or contact him on LinkedIn.