Is coronavirus really mutating to become more dangerous?
Some scientists suggest changes are making the Covid-19 virus more virulent
Scientists have discovered that the new coronavirus has mutated several times - but experts are divided over whether the new variants pose more of a threat.
The spread of one mutation in particular “is worrying”, says Bette Korber, a computational biologist who led a study of the new coronavirus at the New Mexico-based Los Alamos National Laboratory.
Korber and her team report “a mutated form of the virus very rapidly emerging, and over the month of March becoming the dominant pandemic form”.
Another study, at University College London, “identified 198 recurring mutations”, reports the BBC. However, the researchers said there was no evidence that any of the mutations had changed the behaviour of the Sars-CoV-2 virus in any significant way.
“Mutations in themselves are not a bad thing,” said Professor Francois Balloux. “So far, we cannot say whether Sars-CoV-2 is becoming more or less lethal and contagious.”
Why do viruses mutate?
“Mutations are tiny changes to genetic material that occur as it is copied,” says The New York Times. These changes occur at random and most “have little effect”, but sometimes a change will allow the new variant of the virus to spread more easily - or make it more deadly.
While mutations are common, the emergence of a new strain of a virus is more unusual.
Although there’s “no clear, fixed threshold” for what constitutes the latter, “the term has the same connotation in virology as it does colloquially - it implies importance”, says The Atlantic. “Viruses change all the time; strains arise when they change in meaningful ways.”
Has the Covid-19 coronavirus developed different strains?
Apparently not. “The coronavirus is actually quite stable,” says The Guardian’s science editor Ian Sample. “Scientists have analysed about 13,000 samples in Britain since mid-March and found that new mutations appear roughly twice a month.”
Researchers at the University of Glasgow concluded that the mutations identified so far “did not amount to different strains of the virus”, the BBC reports. “They concluded that only one type of the virus is currently circulating.”
Previous coronaviruses have also changed slowly, mutating “at a tenth of the speed” of the flu virus, says The Atlantic.
Is the virus different in each country?
The new coronavirus has mutated as it has spread across the world, and different variants have taken root in different places.
“Researchers in Germany identified three main genetic groups of the virus in April, which they named A, B and C,” says The Guardian’s Sample. “Groups A and C are mostly found in Europeans and Americans, while group B is most common in East Asia.”
The team behind the Los Alamos study have suggested that a more virulent form of the virus, known as Spike D614G, “began spreading in Europe in early February”, reaching the US soon after.
In a research paper outlining their findings, the researchers say that the prevalence of this strain “is increasing in frequency at an alarming rate, indicating a fitness advantage relative to the original Wuhan strain that enables more rapid spread”.
However, other virologists told The Atlantic that “the paper’s claims are plausible, but not justified by the evidence it presents”. The spread of Spike D614G might also be the result of China’s comprehensive lockdown, which trapped other variants within the country’s borders, these critics argue.
Martin Hibberd, a professor of emerging infectious diseases at the London School of Hygiene and Tropical Medicine, told The Guardian that more research was needed to “reveal whether the new mutations help [the virus] spread and whether vaccines may need to be redesigned”.
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Why might vaccines be affected?
The rapidly mutating flu virus requires a new vaccine every year, because antibodies that can fight one strain of influenza may be ineffective against another. By contrast, the stability of the new coronavirus has led scientists working on a Covid-19 vaccine to hope that a single dose might offer long-term protection.
“The Los Alamos report could upend that assumption,” says the Los Angeles Times. “The virus could undergo further mutations even as research organisations prepare the first medical treatments and vaccines… [and] the effectiveness of vaccines could be limited.”
However, there is no evidence that this has happened yet, adds The New York Times, which points out that “unlike the flu, the coronavirus so far has not split into clearly distinct forms”.