Coronavirus mutations not speeding up spread, say scientists

None of the mutations documented in the new coronavirus appear to make Covid-19 spread more rapidly, scientists have said.

However, the researchers from University College London (UCL) have warned the world needs to remain vigilant and continue monitoring the genetic changes in Sars-Cov-2, the virus that causes Covid-19.

This is because the imminent introduction of vaccines may “exert new selective pressures on the virus” that may lead to mutations that do not respond to jabs.

The findings, published in the journal Nature Communications, are based on coronavirus genomes – or genetic material – from more than 46,000 people with Covid-19 from 99 countries.

Lead author Professor Francois Balloux, of UCL Genetics Institute, said: “The news on the vaccine front looks great.

“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.”

First and corresponding author Lucy van Dorp, of UCL Genetics Institute, added: “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.”

Mutations in coronaviruses can develop in three different ways, the researchers said.

These are: mistakes resulting from copying errors as the virus replicates itself inside the human body; through interactions with other viruses infecting the same cell; and changes induced by the host’s or a person’s own immune system.

Scientists from UCL, along with experts from Cirad, the Universite de la Reunion and the University of Oxford, analysed a global dataset of Sars-Cov-2 genomes from 46,723 people, collected up until the end of July 2020.

The teams have so far identified 12,706 mutations in Sars-Cov-2.

The researchers said there is strong evidence that mutations have occurred repeatedly and independently in 398 of the cases.

Based on a modelling of the virus’s evolutionary tree, the scientists said they found no evidence any of the common mutations are increasing the virus’s transmissibility.

Instead, they found most common mutations are neutral for the virus, including one mutation in the virus spike protein called D614G.

HEALTH Coronavirus
HEALTH Coronavirus

The researchers said 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.

However, they added this is in contrast to what happened when Sars-Cov-2 later jumped from humans into farmed minks.

Ms van Dorp said: “When we analysed 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 researchers said that while Sars-Cov-2 will eventually diverge into different lineages as it becomes more common in human populations, it does not necessarily mean these lineages will be more transmissible or harmful.

Ms van Dorp said: “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.”