With vaccines starting to give hope from the pandemic, British authorities warned last weekend of a highly contagious new variant of the coronavirus circulating in England.
With a reference to the rapid spread of the virus in and around London, Prime Minister Boris Johnson has imposed the strictest blockade on the country since March.
“If the virus changes its attack method, we have to change our defense method,” he said.
A crowd trying to run out of the city when the restrictions took effect filled London’s train stations. On Sunday, European countries began closing their borders to travelers from the UK, hoping to block the way to the new version of the pathogen.
A similar version of the virus has surfaced in South Africa that, according to the scientists who discovered it, shares one of the mutations seen in the British variant. That virus has been found in up to 90 percent of samples whose genetic sequences have been analyzed in South Africa since mid-November.
Scientists are concerned about these variants, but are not surprised. Researchers have recorded thousands of minor changes in the genetic material of the coronavirus as it has spread around the world.
Some variants appear in a population only by chance, not because the changes somehow overload the virus. However, as it becomes more difficult for the pathogen to survive, due to vaccines and the increasing immunity of human populations, researchers also hope that the virus will develop useful mutations that will allow it to spread more easily or escape detection. of the immune system.
“It’s a real warning that we need to pay more attention,” said Jesse Bloom, an evolutionary biologist at Fred Hutchinson Cancer Research Center in Seattle. “No doubt these mutations will spread, and eventually the scientific community will need to monitor these mutations and describe what effects they have.”
The British variant has about 20 mutations, including some that affect the way the virus attaches to and infects human cells. These mutations allow the variant to multiply and transfer more efficiently, said Muge Cevik, an infectious disease expert at the University of St Andrew in Scotland and a scientific adviser to the UK government.
The estimate of higher transferability (UK officials said the variant was up to 70 percent more transferable) is based on modeling and has not been confirmed in laboratory experiments, Cevik added.
“Overall, I think we need a little more experimental data,” he said. “We cannot entirely rule out that some of this portability data may be related to human behavior.”
In South Africa, scientists were also quick to point out that human behavior was at the root of the epidemic, not necessarily new mutations whose effect on transmissibility has yet to be quantified.
The UK announcement raised concerns that the virus could evolve to become resistant to the newly released vaccines. The concern is about a number of changes in the virus’s genetic code that make it less vulnerable to certain antibodies.
However, several experts called for caution, arguing that it would take years, not months, for the virus to evolve enough to make current vaccines impotent.
“No one needs to worry about the possibility of a single catastrophic mutation suddenly paralyzing all immunity and antibodies,” said Bloom. “It will be a process that will take place over several years and in which multiple viral mutations will have to be accumulated. It doesn’t work as an on / off switch, ”he added.
The scientific nuance mattered little to the UK’s neighbors. The Dutch, concerned about the potential influx of travelers with the variant, said they would suspend flights from the United Kingdom from Sunday, December 20, 2020 to January 1, 2021.
Italy has also suspended air travel, and on Sunday, Belgian officials issued a 24-hour ban on arrivals from the UK by air or train. Germany is developing a regulation restricting travelers from the UK and South Africa.
According to local media, other countries are also considering a ban, including France, Austria and Ireland. Spain has asked the European Union for a coordinated response to the flight ban. New York Governor Andrew Cuomo asked the Trump administration to consider banning flights from the UK.
In England, transportation officials said they would increase the number of police officers guarding terminals, such as train stations, to ensure that only essential journeys are made. On Sunday, Secretary of Health Matt Hancock said the people packing the trains were “without a doubt irresponsible”.
And he added that the restrictions imposed by Johnson could last for months.
Like all viruses, the coronavirus is a metamorphosis. Some genetic changes are inconsistent, but others can give you an edge.
Scientists are especially afraid of the latter possibility. The vaccination of millions of people can force the virus to make new adaptations, mutations that help it evade or resist the immune response. There are already small changes in the virus that have emerged independently on several occasions around the world, suggesting that the mutations are beneficial to the pathogen.
The mutation affecting antibody sensitivity (whose technical name is deletion 69-70, referring to missing letters in the genetic code) has been observed at least three times: in Danish mink, in humans from the United Kingdom, and in an immunosuppressed patient which became much less sensitive to restorative plasma.
‘This thing is being broadcast. It’s spread. It’s constantly adapting, ”said Ravindra Gupta, a virologist at the University of Cambridge who detailed last week’s recurring emergence and spread of the deletion. “But people don’t want to hear what we’re saying, which is that this virus will mutate,” he added.
The new genetic deletion changes the spike protein (known as protein S) on the surface of the coronavirus, which the virus needs to infect human cells. Variants of the virus with this elimination emerged independently in Thailand and Germany in early 2020 and appeared in Denmark and England in August.
Several recent articles have shown that the coronavirus can evolve to avoid being recognized by a single monoclonal antibody, a mixture of two antibodies, or even a restorative serum administered to a specific individual.
Fortunately, the body’s immune system as a whole is a much more formidable opponent.
The Pfizer-BioNTech and Moderna vaccines only elicit an immune response against protein S on the surface of the coronavirus. However, each infected person produces a wide, unique and complex repertoire of antibodies to this protein.
“Let’s say we have a thousand high caliber weapons targeting the virus,” said Kartik Chandran, a virus expert at the Albert Einstein School of Medicine in New York. “No matter how the virus twists and turns, it’s not that easy to find a genetic solution that can fight all of these different antibody specificities, not to mention the other branches of the immune response.”
In short: the coronavirus, despite the many variants it can adopt, will very difficult to escape the body’s defenses.
In order to escape immunity, a virus must accumulate a series of mutations that allow the pathogen to affect the effectiveness of the body’s defenses. Some viruses, such as influenza, accumulate these changes relatively quickly. But others, like the measles virus, have almost none of the changes.
Even the influenza virus takes five to seven years to collect enough mutations to escape immune recognition completely, Bloom said. His lab released a new report on Friday, Dec. 18, showing that common cold coronaviruses also evolve to escape detection by the immune system, but that happens over many years.
The scale of the infections in this pandemic may result in a rapid diversity in the new corona virus. Still, the vast majority of people around the world have yet to become infected, and that has given scientists hope.
“I would be a little surprised if we saw active selection for immune escape,” said Emma Hodcroft, molecular public health researcher at the University of Bern in Switzerland. “The virus doesn’t have to do that just yet in a population that is largely unexposed, but it is something we want to take care of in the long term, especially if we vaccinate more people,” he explains.
Immunizing about 60 percent of the population over the course of a year and keeping the number of cases low while that happens will reduce the chances of the virus mutating significantly, Hodcroft said.
Still, scientists will have to closely monitor the virus’s evolution to detect mutations that could give it an advantage over vaccines.