Just as vaccines begin to offer hope for a way out of the pandemic, British officials last weekend sounded an urgent alarm over what they called a new highly contagious variant of the coronavirus circulating in England.
Citing the rapid spread of the virus through London and surrounding areas, Prime Minister Boris Johnson imposed the country’s strictest closure since March.
“When the virus changes its method of attack, we have to change our method of defense,” he said.
London train stations were filled with crowds of people traveling to leave the city when the restrictions came into force. On Sunday, European countries began closing their borders to travelers from the UK in hopes of closing the new iteration of the pathogen.
In South Africa, a similar version of the virus has appeared, which shares one of the mutations in the British variant, according to the scientists who detected it. This virus has been found in up to 90% of the samples whose genetic sequences have been analyzed in South Africa since mid-November.
Scientists are concerned about these variants, but they are not surprised. Researchers have seen thousands of small changes in the genetic material of the coronavirus as it has spread around the world.
Some variants become more common in a population simply by luck, not because the changes somehow outweigh the virus. But as the pathogen becomes more difficult to survive, due to vaccinations and growing immunity in human populations, researchers also hope the virus will obtain useful mutations that will allow it to spread more easily or escape detection by humans. immune system.
Read: European countries ban flights from the UK while Britain says new coronavirus strain is “out of control”
“It’s a real warning that we need to pay more attention,” said Jesse Bloom, an evolutionary biologist at the Fred Hutchinson Cancer Research Center in Seattle. “Certainly, these mutations will spread, and definitely the scientific community needs to control these mutations and we need to characterize what effects they have.”
The British variant has about 20 mutations, including several that affect the way the virus blocks and infects human cells. These mutations can allow the variant to reproduce and transmit more efficiently, said Muge Cevik, an infectious disease expert at St. Louis University. Andrews in Scotland and scientific adviser to the British government.
But the estimate of higher transmissibility (British officials said the variant was up to 70% more transmissible) is based on modeling and has not been confirmed in laboratory experiments, Cevik added.
“Overall, I think we need to have a little more experimental data,” he said. “We can’t completely rule out the fact that some of this transmissibility data is related to human behavior.”
Also in South Africa, scientists quickly realized that human behavior was driving the epidemic, not necessarily new mutations the effect of transmissibility yet to be quantified.
The British announcement also raised concerns that the virus could evolve and become resistant to vaccines that are being rolled out right now. Concerns focus on a couple of alterations in the viral genetic code that may make it less vulnerable to certain antibodies.
But several experts called for caution, saying it would take years, not months, for the virus to evolve enough to make current vaccines powerless.
“No one should worry that there will be a single catastrophic mutation that suddenly makes all immunity and antibodies useless,” Bloom said. “It will be a process that takes place over several years and requires the accumulation of multiple viral mutations. It will not be like a power switch. “
The scientific nuance mattered little to Britain’s neighbors. Concerned about the potential influx of passengers carrying the variant, the Netherlands said it would suspend flights from Britain from Sunday to 1 January.
Italy also suspended air travel and Belgian officials on Sunday enacted a ban on UK arrivals by air or train 24 hours a day. Germany is drafting regulations that limit travelers from Britain and South Africa.
Other countries are also considering the ban, including France, Austria and Ireland, according to local media. Spain has asked the European Union for a coordinated response to the flight ban. New York Gov. Andrew Cuomo asked the Trump administration to consider banning flights from Britain.
In England, transport officials said they would increase the number of police officers controlling centers such as railway stations to ensure only essential journeys were made. The country’s health secretary, Matt Hancock, on Sunday called those who packed the trains “clearly irresponsible.”
He also said the restrictions imposed by Johnson could be in place for months.
Like all viruses, coronavirus is a change of form. Some genetic changes are insignificant, but some may give you an advantage.
Scientists are especially afraid of the latter possibility. Vaccination of millions of people can force the virus into new adaptations, mutations that help it evade or resist the immune response. There are already small changes in the virus that have occurred independently several times around the world, suggesting that the mutations are useful for the pathogen.
The mutation that affects susceptibility to antibodies (technically called deletion 69-70, meaning missing letters in the genetic code) has been seen at least three times: in Danish minks, in people in Britain, and in an immunocompromised patient who it became much less sensitive to convalescent plasma.
“It simply came to our notice then. It is to acquire. It adapts all the time, ”said Dr. Ravindra Gupta, a virologist at Cambridge University, who last week detailed the recurring appearance and spread of suppression. “But people don’t want to hear what we say, that is, this virus will mutate.”
The new genetic suppression changes the ear protein on the surface of the coronavirus, which it needs to infect human cells. Virus variants with this suppression emerged independently in Thailand and Germany in early 2020 and became common in Denmark and England in August.
Scientists initially thought the new coronavirus was stable and unlikely to escape the vaccine-induced immune response, said Dr Deepti Gurdasani, a public health clinical researcher at Queen Mary University in London.
“But it has become very clear in recent months that mutations can occur,” he said. “As selection pressure increases with mass vaccination, I think these mutants will become more common.”
Several recent studies have shown that coronavirus can evolve to avoid recognition by a single monoclonal antibody, a mixture of two antibodies, or even convalescent serum given to a particular individual.
Fortunately, the whole body’s immune system is a much more formidable adversary.
Pfizer-BioNTech and Moderna vaccines induce an immune response only to the spike protein that the coronavirus carries on its surface. But each infected person produces a wide unique and complex repertoire of antibodies against this protein.
“The fact is, you have a thousand big guns pointing at the virus,” said Kartik Chandran, a virus expert at Albert Einstein College of Medicine in New York. “No matter how the virus is twisted and thrown, it’s not so easy to find a genetic solution that can really fight all these different antibody specificities, not to mention the other arms of the immune response.”
In short: it will be very difficult for the coronavirus to escape the body’s defenses, despite the many variations it can adopt.
Escape from immunity requires a virus to accumulate a number of mutations, which allow the pathogen to erode the effectiveness of the body’s defenses. Some viruses, such as the flu, accumulate these changes relatively quickly. But others, like the measles virus, pick up virtually none of the alterations.
Even the flu virus needs five to seven years to pick up enough mutations to escape immune recognition, Bloom noted. His lab on Friday released a new report showing that common cold coronaviruses are also evolving to escape immune detection, but over many years.
The scale of infections in this pandemic can quickly generate diversity in the new coronavirus. However, the vast majority of people around the world have not yet been infected, and this has given scientists hope.
“It would be a bit surprising if we saw an active selection for immune leakage,” said Emma Hodcroft, a molecular public health researcher at the University of Bern in Switzerland.
“In a still mostly naive population, the virus still doesn’t need to do that,” he said. “But it’s something we want to keep in mind in the long run, especially when we start vaccinating more people.”
Immunizing about 60 percent of the population in about a year and keeping the number of cases low while this happens will help minimize the chances of a significant mutation in the virus, Hodcroft said.
However, scientists will need to closely monitor the evolving virus to detect mutations that may give vaccines an advantage.
Scientists routinely monitor flu virus mutations to update vaccines and should do the same with the coronavirus, said Trevor Bedford, an evolutionary biologist at the Fred Hutchinson Cancer Research Center in Seattle.
“You can imagine that there is a process like the flu vaccine, in which you change these variants and everyone gets their annual Covid-19 vaccine,” he said. “I think that’s what will usually be needed.”
The good news is that the technology used in Pfizer-BioNTech and Moderna vaccines is much easier to adjust and upgrade than conventional vaccines. New vaccines also generate a massive immune response, so the coronavirus may need many mutations over the years before the vaccines can be modified, Bedford said.
Meanwhile, according to him and other experts, the Centers for Disease Control and Prevention and other government agencies should establish a national system to link viral sequence databases with field data, as if an infection occurred despite vaccination. .
“These are useful tricks for scientists and governments to set up systems, now we may need them, especially when we start vaccinating people,” Hodcroft said. “But the public shouldn’t necessarily be in a panic.”