LONDON – As vaccines are rolling out, the coronavirus is on the move, not merely spreading but also mutating, and possibly becoming more transmissible.
There is no evidence that these changes are making the virus deadlier, but new research has provided evidence that the virus is not a static target of vaccines and will need to be watched closely to see how it responds to therapeutic interventions and the human immune system.
The issue of mutations led to headlines across the United Kingdom after a top government official, Health Secretary Matt Hancock, stood in the House of Commons on Monday and announced that more than 1,000 confirmed coronavirus infections in southeastern England show genetic mutations that might be driving the surge in that region.
That news was quickly followed by a statement from Jeremy Farrar, the head of the Wellcome Trust biomedical research foundation, saying “there is evidence to indicate a new variant of the Covid-19 virus” and calling this development “potentially serious.” He said it is unclear whether the variant is responsible for the spike in infections in parts of the United Kingdom or what this may or may not mean for transmission of the virus and the efficacy of vaccines.
“The pressure on the virus to evolve is increased by the fact that so many millions of people have now been infected. Most of the mutations will not be significant or cause for concern, but some may give the virus an evolutionary advantage, which may lead to higher transmission or mean it is more harmful,” Farrar said.
At a news conference Monday evening, neither Hancock nor England’s chief medical officer, Chris Whitty, released enough data to help the public understand the significance of the new variant.
That left scientists scrambling to fact-check the public pronouncements. More information began trickling out Tuesday.
Scientists who are members of the U.K. Covid-19 Genomics Consortium, which operates government and university laboratories in Britain to track changes to the virus and discovered the variant, stressed that mutations occur all time and that lineages arise and then disappear.
The researchers said they first noted the new variant at the end of September and began following its spread, eventually seeing it in samples taken from more than 1,100 people, most of whom lived in the southeast of England.
What surprised them was the sudden prevalence of the variant.
“This lineage came up quite rapidly,” said Nick Loman, a professor of microbial genomics at the University of Birmingham.
Loman also said the number of mutations was striking. The new variant showed 17 mutations, most in a segment of the virus’s genome that encodes for the spike protein, the protruding structure essential to the pathogen’s ability to bind with the receptor cells in a person who gets exposed and infected.
Loman said there was no proof that this variant is spreading faster. At this point, it could just be chance. Nor is there any sign that the variant causes more severe illness or is capable of evading a vaccine.
He said that it is worth watching closely and that scientists were bringing the variant into the laboratory to study whether it entered cells more easily.
The researchers stressed that such a mutation is not surprising. Sharon Peacock, director of the surveillance consortium and a professor of microbiology at the University of Cambridge, said thousands of mutations in the novel coronavirus have been identified since it emerged.
“The vast number have no impact,” she said. “Mutations are a part of natural life.”
Peacock said virus strains that suddenly become more dominant need to be tracked and studied.
The novel coronavirus – officially, SARS-CoV-2 – jumped into the human species sometime late last year and may still be evolving as it adapts to the new host. The virus is faced with obstacles in the human immune system – millions of people now have antibodies because they’ve been infected and have survived – and from interventions such as therapeutic drugs and vaccines.
“If there’s some kind of hurdle in the way, there’s pressure on the virus to jump over it or adapt in some way,” said Jeremy Luban, a virologist at the University of Massachusetts Medical School. “Then it’s a question of how easy it is given all the biophysical and genetic barriers – whether it’s capable of leaping over the hurdle.”
A paper posted Friday on the medRxiv website – a repository for research that has not yet been peer-reviewed or published in a scientific journal – reported details of a patient in the U.K. who died of covid-19, the disease that can be caused by the novel coronavirus, after a lengthy illness in which the virus mutated in response to antibodies delivered through convalescent plasma.
Another paper posted Tuesday on the bioRxiv site, and also not yet peer-reviewed, reported evidence that mutations that potentially make the virus more infectious “are becoming more common and thought to arise from immune selection pressure.”
Infectious-disease experts say it is still unknown whether any mutations have made or will make real-world differences in the pandemic. Disease severity has not changed as the virus has circumnavigated the planet. Mutations could make the virus less deadly, but to date the decline in mortality among infected people has been attributed entirely to improvements in treatments.
And scientists point out that this virus does not mutate very fast. Although it’s possible that vaccines would need to be modified at some point to remain as effective as they have been so far, this virus is not supernaturally elusive.
“It seems hard to see that this virus is going to be able to evolve its way away from vaccine efficacy,” said Egon Ozer, an infectious-diseases expert at the Feinberg School of Medicine at Northwestern University.
Advancements in genetic sequencing allow the scientific community to monitor the tiniest of changes in the virus as it spreads. The United Kingdom leads the world in genomic scrutiny of the novel coronavirus. Mutations are closely monitored by the U.K. Covid-19 Genomics Consortium, which has high-speed sequencers that study samples from thousands of patients.
Over the past few weeks, some U.K. labs have picked up samples that show the new variant. Hancock, the health minister, was alerted to the new strain Friday evening, and meetings were held before Hancock’s statement Monday in the House of Commons.
The consortium issued a statement that probably proved somewhat difficult for the average person to interpret: “This variant carries a set of mutations including an N501Y mutation in the receptor binding motif of the Spike protein that the virus uses to bind to the human ACE2 receptor.”
Britain was hit hard by waves of infection in the spring and fall, and the fall surge continues. Most of the U.K. population is living under Tier 3 restrictions, meaning pubs are closed and eat-in dining is forbidden.
There were 20,263 new cases Tuesday, and deaths are averaging 400 a day over the past seven days. The first 800,000 doses of the Pfizer vaccine have been distributed, and several million more shots are expected to be delivered by year’s end.
The consensus of virus experts in Britain is that the newly observed variant may offer an advantage to the virus by allowing it to become more transmissible, but the mutation may also be the result of chance events. Such chance eruptions of one variant of the virus can be due to what’s known as the “founder effect”: That variant may simply have arrived early to a geographical region where viral transmission becomes common. Thus, the mutation may not be relevant at all, but was in the right place at the right time.
One mutation affecting the coronavirus spike protein popped up early in the pandemic and became dominant around the planet. Numerous scientific teams have grown persuaded that this mutation – known as the D614G mutation – confers a modest advantage in the ability of the virus to spread. But this remains a contested area of scientific research.
“The good thing about 614G, it’s not more deadly – at least no one has seen any signature of that,” Luban said. But he added, “We don’t know a lot about these viruses yet.”
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Achenbach reported from Washington.