Coronavirus mutations not speeding up spread, study finds

Findings based on analysis of Covid genomes from over 46,000 people from 99 countries

Sam Hancock
Wednesday 25 November 2020 14:04 GMT
Sage member Professor Andrew Hayward warns relaxing restrictions around Christmas could lead to third wave

None of the mutations recorded in the Sars-Cov-2 strain of coronavirus appear to make the virus which causes Covid-19 spread more rapidly, scientists have said.

The findings, published today in the journal Nature Communications, are based on the analysis of coronavirus genomes from over 46,000 people with Covid-19 from 99 countries.

But the University College London (UCL) researchers have who published the research said the world must remain vigilant and continue monitoring the genetic changes.

The warning is based on scientists’ belief that vaccines for Covid-19 – several of which are nearing release – might “exert new selective pressures on the virus”, causing it to mutate as it responds to jabs in ways currently unknown. 

The study’s lead author, Professor Francois Balloux, of UCL Genetics Institute, said the “news on the vaccine front looks great” and that researchers are confident they will “be able to flag” any “vaccine-escape mutations in the future”. 

Crucially, this would “allow updating the vaccines in time if required,” Prof Balloux said. 

First and corresponding author, Lucy van Dorp, also 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.”

Covid-19, a type of RNA virus, can develop mutations 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,
  • 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 Covid-19 genomes from 46,723 people, collected up until the end of July 2020.

While researchers confirmed they have identified 12,706 coronavirus in 398 cases, there is currently no evidence that these “common mutations” are increasing the virus’ transmissibility.

Instead they found that most of these mutations are neutral for the virus, including one in the virus spike protein called D614G.

The study found that most of the common mutations were likely induced by the human immune system, rather than being the result of the virus adapting to its novel human host. Though this is markedly different to what happened when Covid transferred from humans into farmed minks earlier this month, UCL scientists pointed out.

The emergence of a coronavirus mink mutation sparked fears that the virus was spreading further, and becoming more intelligent.  At the time, statistical geneticist Dr Jeffrey Barrett told The Independent: “The virus is mutating all the time, in both humans and any animals it infects, so globally we need to monitor these mutations in case any of them start to spread rapidly.”

Minks are culled in Bording, Denmark, after a spike in Covid cases on one farm

He reminded people it was “important not to panic, though”. He said: “The world has sequenced well over a hundred thousand viral genomes, and the mink mutations so far are extremely rare in people.”

Similarly, Professor Jonathan Stoye told The Independent “we should certainly expect mutations to occur”. While it was possible “that individual mutations” would cause a “reduction in antibody binding”, he said he could not be sure “whether individual changes will show major effects”.

In line with today’s announcement by UCL researchers, Dr Barrett correctly projected that because “so many vaccines” were in the pipeline, “the diversity of ways in which they’re made should help counteract any escape mutations that may develop to specific vaccines”. 

Ms van Dorp, the UCL study’s co-author, said the team of researchers 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”.

But it is perfectly normal for Covid-19 to “diverge into different lineages as it becomes more common in human populations”, she said, and this does not necessarily mean these lineages will be more transmissible or harmful.

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