Scientists in the UK and elsewhere report the discovery of new, potentially important mutations found in local strains of the coronavirus. These strains can pose a real added danger to humans, with early research suggesting they are more transmissible than the classic version. And while there is still much to understand about them, there is also some concern that they may be less vulnerable to the vaccines that have been developed to date.
News about the mutations arose early December. Scientists in the UK, who routinely monitored viral strains from patients in the country, had identified a variant of the coronavirus (SARS-CoV-2) that was beginning to emerge much more in the South East of England. Last week, several other countries reported finding strains with some of the same mutations as the British variant, including the Netherlands and South Africa. This week some countries have announced a new set of tougher travel restrictions to and from the UK, hoping to curb its spread.
Viruses mutate always. Most of the time, these mutations don’t change how a disease-causing virus spreads or reacts to humans. But sometimes yes. Early in the pandemic, a mutation called D614G became widespread and eventually universal in strains of coronavirus. The mutation is now thought to have helped make the virus more transmissible than during the initial outbreaks in China. By the time this mutation had become dominant, the pandemic was already in full swing everywhere – so it didn’t really change our predicament. Nor has it been linked to more serious illness.
There are scientists who remain skeptical that the mutations found in the British variant, known as B.1.1.7, are really relevant. It’s possible that these mutations are just coincidence – “lucky” genetic changes that cling to strains of the virus that would become widely spread anyway. But other experts are less reassured. Last Friday, scientists from the New and Emerging Respiratory Virus Threats Advisory Group (NERVTAG), a group appointed by the UK government, Met to discuss the new species. They concluded, with moderate confidence, that B.1.1.7 has a “substantial increase in transferability compared to other variants.” Since then they have to become even more certain of their conclusion.
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A major reason why the B.1.1.7 variant is of concern is that it contains multiple mutations that can improve the virus’s ability to infect humans. B.1.1.7 is said to have 17 potentially relevant mutations on its spike protein, which the virus uses to enter our cells. Each mutation may not noticeably change the virus’s relationship with humans, but enough of the right ones could. According to Jason McLellan, a molecular biologist at the University of Texas at Austin, in theory, these strains may even help evade the immune response generated by the vaccines we have developed against the coronavirus. McLellan and his team have been studying coronaviruses since before this pandemic, and they have contributed until the development of Moderna’s now-approved covid-19 vaccine, as well as several antiviral treatments in development.
“A single point mutation probably wouldn’t affect a vaccine as much because the vaccine generates a so-called polyclonal response, which means that many different antibodies target different parts of the spike protein. In general, it can be difficult for a viral strain to escape so many different antibodies attacking the peak with just one mutation, “McLellan told Gizmodo over the phone.
However, he noted that the B.1.1.7 variant appears to have several mutations that may be relevant to vaccines or other treatments. In particular, there are several genetic bits that help form the N-terminal domain of the spike protein that have been deleted in these strains. The N-terminal domain is one key area those antibodies against the coronavirus target, and it is possible that these changes could affect how well vaccination-trained antibodies effectively recognize and neutralize the virus.
So I think there is some concern, he said. “I don’t know how much it can affect the effectiveness of a vaccine, but I’m sure it will be tested in the coming weeks.”
One way to test the effectiveness of a vaccine against new strains is to collect antibodies from the blood of people who have already been vaccinated. Their response to the new variants can then be compared to their response to strains collected earlier in the pandemic. If they do noticeably worse against the newer variety, that’s a sign of trouble.
It’s worth noting that some experts are less concerned about these mutations and their potential to have a meaningful impact on our efforts to end the pandemic, at least for now.
“SARS-CoV-2 mutates much more slowly than influenza,” Soumya Swaminathan, WHO chief scientist, said at a news conference on Monday. “And so far, although we have seen a number of changes and a number of mutations, none have had a significant impact on the susceptibility of the virus to the therapies, drugs or vaccines currently being used, and it is hoped that that will will remain so. “
Even if this variant is medically important, it does not mean that it cannot be stopped. Viruses and other pathogens evolve over time to adapt to our immune system or the weapons we develop against them, but we can adapt right away. Vaccines can be tweaked in flight to better suit the germ they target, even if it’s noticeably mutated – something that’s done every year for flu. And no matter what happens with B.1.1.7, scientists will have to keep an eye out for strains that could escape the grip of a vaccine in the near future.
“I would be optimistic that these mutations will not significantly affect the efficacy of the vaccine, but it could have some impact,” said McLellan. “And really, what we need to know is the magnitude of the impact.”
The situation on the ground is unlikely to change much for now. The coronavirus is still spreading widely and is making people everywhere sick, and vaccines won’t make major progress in slowing the pandemic at best early next year. Understandably, if you are concerned about these mutations, then that is all the more reason to remain vigilant and reduce your risk of catching and spreading covid-19 to others. Simply put, the fewer chances we give the coronavirus to infect us, the less threat it will be, both new and old versions.