By Apoorva Mandavilli – NYT
Just as vaccines begin to offer hope for a path out of the pandemic, officials in Britain this past weekend sounded an urgent alarm about what they called a highly contagious new 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 most stringent lockdown since March. “When the virus changes its method of attack, we must change our method of defense,” he said.
Train stations in London filled with crowds of people scrambling to leave the city as the restrictions went into effect. On Sunday, European countries began closing their borders to travelers from the United Kingdom, hoping to shut out the new iteration of the pathogen.
In South Africa, a similar version of the virus has emerged, sharing one of the mutations seen in the British variant, according to scientists who detected it. That virus has been found in up to 90 percent of the samples whose genetic sequences have been analyzed in South Africa since mid-November.
Scientists are worried about these variants but not surprised by them. Researchers have recorded thousands of tiny modifications in the genetic material of the coronavirus as it has hopscotched across the world.
Some variants become more common in a population simply by luck, not because the changes somehow supercharge the virus. But as it becomes more difficult for the pathogen to survive — because of vaccinations and growing immunity in human populations — researchers also expect the virus to gain useful mutations enabling it to spread more easily or to escape detection by the immune system.
“It’s a real warning that we need to pay closer attention,” said Jesse Bloom, an evolutionary biologist at the Fred Hutchinson Cancer Research Center in Seattle. “Certainly these mutations are going to spread, and, definitely, 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 several that affect how the virus locks onto 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 the University of St. Andrews in Scotland and a scientific adviser to the British government.
But the estimate of greater transmissibility — British officials said the variant was as much as 70 percent more transmissible — is based on modeling and has not been confirmed in lab experiments, Dr. Cevik added.
“Over all, I think we need to have a little bit more experimental data,” she said. “We can’t entirely rule out the fact that some of this transmissibility data might be related to human behavior.”
In South Africa, too, scientists were quick to note that human behavior was driving the epidemic, not necessarily new mutations whose effect on transmissibility had yet to be quantified.
The British announcement also prompted concern that the virus might evolve to become resistant to the vaccines just now rolling out. The worries are focused on a pair of alterations in the viral genetic code that may make it less vulnerable to certain antibodies.
But several experts urged caution, saying it would take years — not months — for the virus to evolve enough to render the current vaccines impotent.
“No one should worry that there is going to be a single catastrophic mutation that suddenly renders all immunity and antibodies useless,” Dr. Bloom said.
“It is going to be a process that occurs over the time scale of multiple years and requires the accumulation of multiple viral mutations,” he added. “It’s not going to be like an on-off switch.”
The scientific nuance mattered little to Britain’s neighbors. Worried by the potential influx of travelers carrying the variant, the Netherlands said it would suspend flights from Britain from Sunday until Jan. 1.
Italy also suspended air travel, and Belgian officials on Sunday enacted a 24-hour ban on arrivals from the United Kingdom by air or train. Germany is drawing up regulations limiting travelers from Britain as well as from South Africa.
Other countries are also considering bans, among them France, Austria and Ireland, according to local media. Spain has asked the European Union for a coordinated response to banning flights. Gov. Andrew Cuomo of New York asked the Trump administration to consider banning flights from Britain.