SINGAPORE: 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.
In view of the “deteriorating situation”, Singapore's Ministry of Health (MOH) announced on Tuesday (Dec 22) that long-term pass holders and short-term visitors with recent travel history to Britain will be barred from entering or transiting through Singapore from 11.59pm on Wednesday.
Returning Singapore citizens and permanent residents will be required to undergo a COVID-19 polymerase chain reaction (PCR) test upon arrival in Singapore, at the start of their 14-day stay-home notice.
Singapore joins a growing number of countries that have imposed travel bans on 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.
But the strain is notable because it accounts for an increasing proportion of cases in parts of England, and the number of cases and number of regions reporting infections from it are growing, according to the COVID-19 Genomics Consortium UK (COG-UK).
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?
“While the strain has been suggested to be more transmissible, there is currently insufficient evidence to determine if this strain is associated with any change in disease severity, antibody response or vaccine efficacy,” said MOH on Tuesday.
It added that these aspects are being investigated by British authorities, and it will evaluate the data as more emerges.
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.
READ: Singapore researchers discover milder COVID-19 strain, opening up new avenues for treatment and vaccine development
COG-UK cited research on this variant in its report on B.1.1.7, because of a similar deletion of the protein ORF8 in both strains.
The “Singaporean strain” was associated with “milder clinical infection and less post-infection inflammation”, and it died out at the end of March after control measures were implemented, said COG-UK.
Also in August, a strain of the virus with a D614G mutation, which appeared to be more infectious but less deadly, was detected in Singapore and Malaysia.
READ: COVID-19 virus mutation that is '10 times' more infectious detected in Malaysia – Health director-general
As mutations continue to arise, novel combinations of mutations are also increasingly observed, COG-UK said.
In the case of B.1.1.7, all three mutations highlighted by COG-UK have previously been observed and described by scientists in other strains. However, how they affect the coronavirus when present in combination is not known.
According to COG-UK, this new variant also has an “unusually large” number of genetic changes, comprising 23 mutations, 14 amino acid changes and three deletions.
In particular, the accrual of 14 amino acid changes prior to detection of the variant is “to date, unprecedented in the global virus genomic data for the COVID-19 pandemic”, said COG-UK.
HOW ARE GOVERNMENTS RESPONDING TO THE NEW STRAIN?
In England, around 16.4 million people, or 31 per cent of the population, have come under the strictest “tier four” measures, including “stay at home” orders and closures of non-essential shops.
Other parts of the UK have also tightened measures.
Wales introduced a strict lockdown on Dec 20, while Scotland has banned travel to and from other UK regions for Christmas. Both Scotland and Northern Ireland will enter fresh lockdowns on Dec 26.
Outside of Britain, this strain of the coronavirus has been detected in Australia, Denmark and the Netherlands, according to the World Health Organization in an interview with the BBC.
To prevent the spread of the new variant, several destinations are closing their doors to travellers from Britain.
France has blocked people and goods from crossing the Channel, while European neighbours Germany, Ireland, Italy, Austria, Romania, the Netherlands and Belgium have said they will block air travel.
Hong Kong, India, Canada, Iran, Pakistan, Poland, Spain, Switzerland, Sweden, Russia and Jordan have suspended travel for Britons, while Saudi Arabia, Kuwait and Oman have closed their borders completely.
WILL VACCINES BE EFFECTIVE AGAINST THE NEW STRAIN?
Britain became the first country in the world to deploy the Pfizer-BioNTech COVID-19 vaccine earlier this month, and its roll-out of the vaccine continues.
“There is currently no evidence to suggest that the Pfizer vaccine would not protect people against the new strain,” according to PHE.
The agency said that further laboratory work is being undertaken “as a priority” to understand this issue.