Over the weekend, Britain reported a new variant of the coronavirus that Prime Minister Boris Johnson said could be “up to 70 per cent more transmissible”.
British Health Secretary Matt Hancock has described the strain as being “out of control”, with the country imposing a strict Christmas lockdown to slow its spread.
A growing number of countries have also responded by imposing travel bans with Britain to prevent the new strain spreading within their borders.
Here’s what we know about this variant of the virus so far.
WHERE AND WHEN DID THE NEW VARIANT EMERGE?
The new strain came to light in Britain in late November. Officials investigating why COVID-19 infection rates in Kent were not falling despite national measures discovered a rapidly spreading cluster in south-east England and London linked to a variant of the coronavirus.
Backwards tracing using genetic evidence suggested that the variant first emerged in September, said government agency Public Health England (PHE). It then circulated at “very low levels” in the population until mid-November.
Much is still not known about this strain of the virus, known as the B.1.1.7 lineage.
What is a mutation?
A mutation means a change in the genetic sequence of the virus. In the case of SARS-CoV-2, which is an RNA virus, a mutation means a change in the sequence in which its molecules are arranged. A mutation in an RNA virus often happens when the virus makes a mistake while it is making copies of itself.
Only if the mutation results in a significant change in the protein structure can the course of a disease be altered, said Prof V Ravi, retired Head of the Department of Neurovirology at NIMHANS (National Institute of Mental Health and Neuro-Sciences), Bengaluru.
WHAT ARE THE MUTATIONS IN THIS NEW STRAIN?
The variant has an “unusually large” number of genetic changes, according to COG-UK. The consortium’s analysis highlights three mutations that may be biologically significant.
All three mutations are located in the virus’ spike protein, which is associated with viral entry into cells and is relevant in the context of immunity and vaccine efficacy.
The first mutation, called N501Y, alters the receptor binding domain of the spike protein. This is where the virus binds with the human ACE-2 receptor to enter human cells.
N501Y is found to increase binding affinity between the virus and the human receptor, according to COG-UK. In studies with mice, such a mutation is associated with increased infectivity and virulence.
The second mutation involves the deletion of two amino acids and is associated with the virus’ ability to evade the human immune response. It was previously observed in the mink-associated outbreak in Denmark.
The third mutation, called P681H, is located immediately adjacent to the furin cleavage site on the spike protein, which is “a known location of biological significance”.
Scientists at COG-UK hypothesise that the new variant may have come from transmission of the virus by a chronically infected individual.
“This is based on observations that a high rate of mutations may accumulate in immunocompromised patients with chronic infections” of COVID-19, said the consortium.
SHOULD I BE WORRIED?
Data suggests that B.1.1.7 transmits more easily than other strains, according to PHE, which is coordinating the British government’s investigations into the new variant.
Infection rates in geographical areas where this strain has been circulating have increased faster than expected, the agency said.
Modelling evidence also demonstrates that it has a higher transmission rate than other variants currently circulating.
However, PHE said it had “no evidence” that the variant is more likely to cause severe disease or mortality in an update on Dec 20.
“We continue to study cases to understand this better. We know that mortality is a lagging indicator and we will need to continually monitor this over the coming weeks,” PHE said.
“The way to control this virus is the same, whatever the variant,” the agency added, urging people to avoid close contact with others, wash their hands and wear a mask.
HAVE MUTATIONS OF THE CORONAVIRUS SPREAD BEFORE?
Thousands of mutations have already arisen in the coronavirus’ genome since late 2019, according to COG-UK.
“Mutations arise naturally in the SARS-CoV-2 genome as the virus replicates and circulates in the human population,” the consortium said in a December report on mutations of special interest.
Some of these mutations have previously been found in Singapore. For example, in August, Singapore discovered a variant of COVID-19 that caused less severe symptoms in patients.
Is a mutation in the spike protein particularly significant?
Dr Gagandeep Kang, Professor at Christian Medical College, Vellore, said that in general, there would be more concern about a mutation in the spike region than other regions of the coronavirus genome. It is the coronavirus spike protein that binds to a human protein to initiate the process of infection. So, changes here could possibly affect how the virus behaves in terms of its ability to infect, or cause severe disease, or escape the immune response made by vaccines — but these are theoretical concerns at the moment, Dr Kang said.
Through the pandemic, over 4,000 mutations have been detected in the spike region. This one appeared initially in Brazil in April, in a small proportion of cases. Since numbers have gone up in the UK, Dr Gang stressed the need to understand why the increase and what it means. At the moment, however, there is no data to indicate severity or faster spread.
Will vaccines still be effective?
The extent to which SARS-CoV-2 may evolve to escape immunity induced by infection or vaccination isn’t currently known. Studies are under way to understand that better. The WHO’s van Kerkhove told the BBC that current information suggests that the new variant doesn’t have any impact on the vaccines being rolled out. Over time, as more mutations occur, vaccines may need to be altered. This happens with seasonal flu, which mutates every year, and the vaccine is adjusted accordingly. Unlike flu, coronaviruses have a proof-reading mechanism that means they don’t mutate as quickly as the flu virus. Covid-19 vaccines that have so far proved effective in trials can be easily tweaked if necessary, the BMJ medical journal reported on Dec. 16.