As vaccines begin to give hope for a way out of the pandemic, UK officials have issued an urgent alarm over the past weekend about what they have 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 blockade in March.
“When the virus changes its method of attack, we need to change our method of defense,” he said.
London’s train stations were filled with crowds rushing out of the city as the restrictions came into force. On Sunday, European countries began closing their borders for travel in the United Kingdom, hoping to rule out the new iteration of the pathogen.
In South Africa, a similar version of the virus has emerged, which shares one of the mutations observed in the British version, according to the scientists who detected it. This virus has been found in up to 90% of samples whose genetic sequences have been analyzed in South Africa since mid-November.
Scientists are worried about these variants, but they are not surprised by them. Researchers have seen thousands of tiny changes in the genetic material of coronavirus as it has appeared around the world.
Some variants become more common in a population simply by luck, not because the changes somewhat overload the virus. But as the pathogen becomes more difficult to survive – due to vaccinations and growing immunity in human populations – researchers also expect the virus to make useful mutations, allowing it to spread more easily or get rid of detection of the immune system.
Read: European countries ban flights from the UK, because the UK says the 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 certainly the scientific community, we need to monitor these mutations and we need to characterize which ones have effects.”
The British variant has about 20 mutations, including some that affect how the virus gets stuck in human cells and infects them. These mutations may allow the variant to replicate and transmit more efficiently, said Muge Cevik, an infectious disease expert at St. Louis University. Andrews of Scotland and Scientific Adviser to the British Government.
But the estimate of higher transmissibility – British officials said the variant is 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,” she said. “We cannot completely rule out the possibility that some of this transmissibility data may be related to human behavior.”
And in South Africa, scientists have quickly noticed that human behavior has driven the epidemic, not necessarily new mutations whose effect on transmissibility has not yet been quantified.
The British announcement also raised concerns that the virus could evolve to become resistant to vaccines right now. Concerns are focused on a couple of changes to the viral genetic code that may make it less vulnerable to certain antibodies.
But several experts have called for caution, saying it will take years – not months – for the virus to evolve enough to make current vaccines impotent.
“No one should worry that there will be a single catastrophic mutation that will render all immunities and antibodies useless,” Bloom said. It will be a process that takes place over a period of time and requires the accumulation of multiple viral mutations. It won’t 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 has said it will suspend flights from the UK from Sunday to January 1.
Italy also suspended air travel, and Belgian officials on Sunday adopted a 24-hour ban on arrivals from the United Kingdom by plane or train. Germany is developing regulations that limit travel from the UK as well as from South Africa.
Other countries are also considering bans, including France, Austria and Ireland, according to local media. Spain has called on the European Union for a coordinated response to a flight ban. New York Governor Andrew Cuomo has called on the Trump administration to consider banning flights from Britain.
In England, transport officials have said they will increase the number of police officers monitoring hubs, such as railway stations, to ensure that only essential journeys are made. The country’s health secretary, Matt Hancock, on Sunday called those who pack the trains “clearly irresponsible”.
He also said the restrictions imposed by Johnson could be in place for months.
Like all viruses, coronavirus changes shape. Some genetic changes are inconsequential, but some may give them an advantage.
Scientists are especially afraid of the latter possibility. Vaccination of millions of people can force the virus to make new adaptations, mutations that help it evade or resist the immune response. Already, there are small changes in the virus that have occurred independently several times around the world, suggesting that mutations are useful to the pathogen.
The mutation that affects the susceptibility of antibodies – technically called deletion 69-70, meaning missing letters in the genetic code – has been seen at least three times: in Danish minks, in humans in the UK and in an immune-suppressed patient it became much less sensitive to convalescent plasma.
“It simply came to our notice then. It is acquired. It adapts all the time, ”said Dr. Ravindra Gupta, a virologist at the University of Cambridge, who last week detailed the recurring appearance and spread of the erasure. “But people don’t want to hear what we’re saying, this virus will move.”
The new genetic deletion alters the spike protein on the surface of the coronavirus, which it needs to infect human cells. Variants of the virus with this elimination appeared independently in Thailand and Germany in early 2020 and became widespread 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 clinical researcher in public health at Queen Mary University in London.
“But it has become very clear in the last few months that mutations can occur,” she said. “As selection pressure increases with mass vaccination, I believe 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 a convalescent serum given to a specific individual.
Fortunately, the body’s entire immune system is a much more formidable adversary.
Pfizer-BioNTech and Moderna vaccines induce an immune response only to the spike protein carried by the coronavirus on its surface. But each infected person produces a wide, unique and complex repertoire of antibodies against this protein.
“The fact is that you have a thousand large weapons aimed at the virus,” said Kartik Chandran, a virus expert at Albert Einstein College of Medicine in New York. No matter how the virus twists and weaves, it is not so easy to find a genetic solution that can really fight all these different specificities of antibodies, not to mention the other arms of the immune response.
In short: it will be very difficult for the coronavirus to get rid of the body’s defenses, despite the many options it can adopt.
Escape from immunity requires a virus to accumulate a series of mutations, each allowing the pathogen to erode the body’s defense efficiency. Some viruses, such as the flu, accumulate these changes relatively quickly. But others, such as the measles virus, collect almost no change.
Even the flu virus needs five to seven years to collect enough mutations to completely escape immune recognition, Bloom noted. His lab released a new report Friday showing that common cold coronaviruses are also evolving to get rid of immunity 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 little surprising for me to see active selection for immune escape,” said Emma Hodcroft, a molecular public health researcher at the University of Bern in Switzerland.
“In a population that is still mostly naive, the virus just doesn’t have to do that yet,” she said. “But it’s something we want to pay attention to in the long run, especially since we’re starting to vaccinate more people.”
Immunizing about 60 percent of a population in about a year and keeping the number of cases low while this is happening will help minimize the chances of the virus moving significantly, Hodcroft said.
However, scientists will need to closely monitor the evolving virus to detect mutations that may give it an advantage over vaccines.
Scientists routinely monitor influenza virus mutations to update vaccines, and they should do the same for coronavirus, said Trevor Bedford, an evolutionary biologist at the Fred Hutchinson Cancer Research Center in Seattle.
“You can imagine that there is a process similar to the flu vaccine, in which you change these variants and everyone gets the annual Covid-19 vaccine,” he said. “I think that will generally be necessary.”
The good news is that the technology used in Pfizer-BioNTech and Moderna vaccines is much easier to adapt and update than conventional vaccines. The new vaccines also generate a massive immune response, so the coronavirus may need many mutations over the years before the vaccines are modified, Bedford said.
Meanwhile, he and other experts said the Centers for Disease Control and Prevention and other government agencies should set up a national system to link viral sequence databases to ground-based data – such as whether an infection has occurred. despite vaccination.
“These are useful ideas for scientists and governments to implement systems – now before we need them, especially when we start vaccinating people,” Hodcroft said. “But the public doesn’t have to panic.”