Emergence of a new coronavirus variant raises concerns

A single mutation — N501Y — in the virus spike protein has been found to increase the binding affinity thereby making the variant more transmissible. There is currently no evidence that the new variant can cause any change in disease severity or increase the risk of reinfection. While the mutations are unlikely to make the vaccines less effective, the emergence of the variant underscores the need for vaccine surveillance.

With nearly a dozen countries in Europe and elsewhere temporarily banning travel from the UK after a new variant of the novel coronavirus was found to be causing an increased number of new cases there, India too temporarily suspended flights, with some exceptions, from the UK effective Tuesday night till December 31.

On Saturday, the UK imposed strict restrictions in greater London and much of the southeast of England to stop the spread of the variant, which has become one of the dominant ones. 

The variant — VUI-202012/01 (the first ‘variant under investigation’ in December 2020) — has 17 mutations in all. Though a few of the 17 mutations are seen in the region of the virus that binds to the human receptor, a single mutation — N501Y — has been found to increase the binding affinity thereby making the variant more transmissible.

Increasing spread

On December 20, the COVID-19 Genomics UK Consortium, which analyses genome data of the virus and identified the variant on September 20, said the variant has been “growing in frequency” since November 2020 and is “responsible for an increasing proportion of SARS-CoV-2 cases in the UK”.

Based on modelling, the variant has been found to be 70% more transmissible but this is yet to be confirmed in lab experiments. According to a December 20 report of the European Centre for Disease Prevention and Control, preliminary study has shown that the variant has the potential to increase by over 0.4 the number of people a person can infect. There is currently no evidence that the new variant can cause any change in disease severity or increase the risk of reinfection.

Will vaccines be less effective against the variant?

Though the N501Y and other mutations are found in the spike protein region of the virus, it is unlikely that the mutations would make the two COVID vaccines that have secured emergency use approval and the ones in final stages of testing less effective. This is because vaccines produce antibodies against many regions of the spike protein, and there is also the T-cell immunity that would come into play to clear the virus. However, as the virus accumulates more mutations, there is a possibility that COVID vaccines might require tweaking.

The emergence of the new variant underlines the compulsion to undertake vaccine surveillance to track effectiveness and to look for the appearance of vaccine-escape mutants.

How the variant evolved

SARS-CoV-2 being an RNA virus tends to have a higher mutation rate, but the presence of 17 mutations, an unusually high number, strongly suggests that the variant has not emerged through gradual accumulation of mutations. According to COG-UK, it is probably due to prolonged infection in a single patient, potentially with reduced immunocompetence.

While a few cases caused by the new variant have been reported in a few countries, the extent of international spread remains unknown. Since far fewer SARS-CoV-2 genomes are sequenced at regular intervals in India, it is unclear if the variant is already present here.

The emergence of the new variant with increased transmissibility is one more reason why non-pharmaceutical interventions should be strictly adhered to.

Published in The Hindu on December 22, 2020