LONDON – British public health officials were perplexed. Restrictions across the country were reducing the spread of coronavirus across much of the country in late November. But in a southeastern part of England, infections were inexplicably increasing.
Epidemiologists began to investigate, at first assuming that there was some kind of over-disseminating event or that people were ignoring the rules of social detachment at work, at illegal parties or elsewhere. They found nothing. Puzzled, they turned to a team of scientists who monitored mutations in the virus’ genome.
On December 8, the group, known as Covid-19 Genomics UK Consortium, found a new variant of the virus, with 23 mutations, in a sample taken from a patient in Kent, near the center of the outbreak in late September. They found the same variant in someone tested in London a day later.
Some of the new mutations had the potential to increase the transmissibility of the virus.
“The gathering of genome data and details of an outbreak in Kent led to the key connection,” said Sharon Peacock, a microbiologist at the University of Cambridge who leads the genomics team. She said in an e-mail that it was the “lamp moment” of scientists.
Out of control
The United Kingdom increased restrictions after announcing a new variant of the coronavirus that appears to be more transmissible.
Percentage change of two weeks in new cases of Covid-19 confirmed daily
Note: Change in Luxembourg calculated using data from Dec.10; Spain from December 9th.
Source: Johns Hopkins CSSE
New information continued to arrive and the British government first raised concerns about the variant publicly on December 14, when Health Secretary Matt Hancock told British lawmakers that he had been responsible for 1,000 cases in London and south-east England and that it was spreading.
“The initial analysis suggests that this variant is growing faster than the existing variants,” said Hancock.
Meanwhile, scientists were further investigating the nature of the mutations in the new variants.
Viruses mutate all the time – although coronaviruses are slower than some other common viruses, like the flu. What stood out in the new variant was that a greater than normal number of mutations affected the code of the amino acids that produce the proteins that make up the virus.
A mutation alters the virus’ spike protein in a way that is known to make it easier for the virus to adhere to cell walls and enter the body. Along with two other mutations, the change has the potential to give the variant a possible advantage over previous versions for infecting people.
It was a variant never seen before – and the number and nature of its mutations, scientists say, is unprecedented.
“It’s kind of a branch, it’s really impressive, in fact, that it’s so different from everything else in the UK,” said Peacock.
At the time of the discovery of the new variant, it represented 62% of all cases registered in London. And infections continued to increase rapidly.
The latest data shows that the average seven-day week through Wednesday across the UK has increased by 61% over the previous week, despite the drop in case count in most of the rest of Europe. Hospitalizations and deaths – lagging indicators of the spread of the virus – increased by 16% and 20%, respectively.
“The underlying mechanism” that drives rapid spread “is not entirely clear – it may be because the virus replicates faster, which means you get higher viral loads, which means you are more infectious,” Peter Horby, president New Emerging Respiratory Virus Threats Advisory Group advising the British government, he told lawmakers on Wednesday.
Another hypothesis is that the time elapsed between exposure and contagion is shorter, which would lead to faster transmission. “Or it could mean that the infection lasts longer,” said Horby.
Researchers are now working to answer two crucial questions: Will the new variant cause more serious illness and be able to escape vaccines?
British scientists say they do not have enough evidence at the moment to answer definitively, but they are working hard to find out.
In the vaccine, they are testing blood samples from people who received the vaccine against the new variant to see if they show a different response compared to that provoked by the previous version.
The general view among Pfizer scientists and developers Inc.
– The BioNTech SE vaccine, is that the vaccine produces antibodies that attack several different sites of the virus, therefore, changes in a small area are unlikely to neutralize the vaccine’s potency.
Regarding the severity of the disease caused by the new variant, they await the hospitalization and death data, which are left behind in the case count, to tell them more.
As they investigated the new variant, British researchers have spent the past few weeks silently hunting for patient zero. They examined the contacts of the two people who were the first identified with the variant, none of whom were sick and others who were infected at the beginning.
One hypothesis is that the variant appeared in a person with a compromised immune system. People with poor immune systems are often the host when viruses undergo a large number of mutations because the virus is able to survive in their system for a long time.
“Ideally, you would know who the index case is,” said Dr. Peacock. “We don’t know at all, if it came up with a patient in the UK or if it was introduced, we can’t categorically say at the moment.”
In the week following the release of the new variant, new data and epidemiological modeling left British scientists increasingly convinced that the new variant reproduced faster than its predecessors. Some models suggested that it was 50% to 70% more transmissible than other versions.
On December 18, as new infections in the region continued to accelerate, a meeting between government officials and scientists alarmed the government, leading to a significant change in policy.
The next day, Prime Minister Boris Johnson announced new blocks to regions where the virus was spreading rapidly and reduced the planned relaxation from five days of restrictions for Christmas to just one day in the rest of the country.
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