The Hindu Explains | Are viruses expected to change form, and will vaccines protect against a mutating SARS-CoV-2?

Why do viruses mutate? How was the new SARS-CoV-2 strain, B 1.1.7, identified?

Published - December 27, 2020 01:45 am IST

A pedestrian walks past coronavirus information signs at Walthamstow in northeast London on December 23, 2020.

A pedestrian walks past coronavirus information signs at Walthamstow in northeast London on December 23, 2020.

The story so far: A year after the novel coronavirus announced itself in China , there was yet another critical update in December this year — the emergence of a new strain of the virus , caused by mutations, that seemed to be 70% more transmissible. Mutations were reported from different parts of the world, including Denmark, Australia, England and South Africa, but the rapid domination of the new strain — lineage B 1.1.7 — in the south of England set off a chain of events, including curbs on travel and Christmas celebrations in the country, and several nations temporarily suspending flights originating from the United Kingdom.

What is the WHO saying?

Speaking about the new English variant, World Health Organization (WHO) chief Tedros Adhanom Ghebreyesus cited a basic fact of virology, that viruses mutate over time and it is natural and is to be expected. Trying to counter many ill-informed discussions triggered by panic from the usage of the word ‘mutation’, he said the U.K. had reported that the transmission was higher, but there was no evidence that it causes a more severe disease . Ongoing studies will clear the air on this angle.

Explained | The new coronavirus variant in Britain

Why do viruses mutate?

Mutation is part of the life cycle of a virus. Once the virus latches on to a host, it begins to replicate and make copies of itself. During the process of virus replication, random errors arise, one or two protein molecules change, possibly induced by the immune response mounted within infected people, explains P.B. Rajesh, vice-president, Royal College of Surgeons of Edinburgh, U.K. These changes in the genomic structure of the virus can be considered mutations. Not all mutations are significant, but those that affect the virus’s ability to survive or replicate are important.

How was the new strain identified?

The English variant was identified in genomic surveillance by COVID-19 Genomics UK (COG-UK), a consortium that analyses genome sequencing data from the U.K. On its website, COG-UK says, “Mutations arise naturally in the SARS-CoV-2 genome as the virus replicates and circulates in the human population ... As a result of this on-going process, many thousands of mutations have already arisen in the SARS-CoV-2 genome since the virus emerged in 2019 … The vast majority of the mutations observed in SARS-CoV-2 have no apparent effect on the virus and only a very small minority are likely to be important and change the virus in any appreciable way (for example, a change in the ability to infect people; cause disease of different severity; or become insensitive to the effect of the human immune response including the response generated by a vaccine).”

The variant is the result of multiple mutations in the spike protein (the point of viral entry into the host) of SARS-CoV-2, as well as mutations in other genomic regions of the RNA virus. COG-UK reportedly identified one of these mutations as ‘N501Y’, in an area of the spike protein that binds to a key protein in the human cell, the ACE2 receptor. This was an indication that the alterations may, theoretically, result in the virus becoming more infectious, it said.

Coronavirus | New, more contagious coronavirus strain in U.K. does not appear to be deadlier: Vivek Murthy

As of December 13, according to Public Health England (PHE), there were 1,108 cases of the variant identified “predominantly in the South and East of England”. The U.K. government’s website explains that backwards tracing using genetic evidence suggests this variant emerged in September 2020 and then circulated at very low levels in the population until mid-November.

The increase in cases linked to the new variant first came to light in late November when PHE was investigating why infection rates in Kent were not falling despite national restrictions. They then discovered a cluster linked to this variant that was spreading rapidly into London and Essex.

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Can it be detected through PCR tests?

Does the PCR test done to detect the virus also pick up this variant, or is it harder to detect? Answering the oft-asked question, Dr. Rajesh says the PCR test is used to identify a number of gene targets and will pick up this variant too. The U.K.’s Chief Medical Officer, Chris Whitty, has said that current swab tests are able to identify the new variant.

Is it known how a vaccine will react?

While studies are on to determine the impact of the vaccine on severity of disease or mortality, Dr. Rajesh explains, “What we need to know about the new variant is its implication for the vaccine, but at this point of time, it is unknown. It is still early to be certain. Ongoing work is something we are looking forward to. What does this variation do for a vaccine which will any way stimulate a broad antibody response? The hope is that it won’t be significantly hampered by the mutation.”

Coronavirus | U.K. strain unlikely to affect efficacy of vaccines, say scientists

Vincent Rajkumar, haematologist and oncologist at Mayo Clinic, in Minnesota, United States, however, urges nations to soldier on with vaccination. “The worry is whether the vaccine will have an impact on the new variant strain because the amino acid sequence in the spike is altered. But my response to this is: vaccines, vaccines, vaccines. Vaccines will reduce the number of people who get infected, reduce the number of people spreading the infections, lower the number of hosts, lower the chances of further mutations, and allow us to get things under control.”

Vaccines will offer protection even from a mutant virus. By their very nature, they will make a variety of different antibodies and memory cells that will help fight off the infection, he adds.


How can you protect yourself?

Simply by following the original advice on COVID-19 hygiene. Using a face mask, regularly washing hands, and maintaining distance with others when in a public setting will continue to be the best practical ways to prevent the infection, experts insist.

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