Virus variant: On temporary travel ban from U.K.

Increased transmissibility is one more reason to follow non-pharmaceutical interventions

With nearly a dozen countries in Europe and elsewhere temporarily banning travel from the U.K. after a new variant of the novel coronavirus was found to be causing an increased number of new cases there, India too has followed suit — flights, with some exceptions, have been temporarily suspended from Tuesday night till December 31. On Saturday, the U.K. imposed strict restrictions in greater London and much of southeast England. The variant — VUI-202012/01 (the first ‘variant under investigation’ in December 2020) — has 23 mutations in all. Though a few of these 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, making the variant more transmissible. On December 20, the COVID-19 Genomics UK Consortium, which 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, it has been found to be 70% more transmissible but this is yet to be confirmed in lab experiments. The European Centre for Disease Prevention and Control says that in a preliminary study, the variant has the potential to increase by over 0.4 the number of people a person can infect. There is no evidence as yet that it can cause any change in disease severity or increase the risk of reinfection.

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 vaccines might require minor tweaking. The emergence of the new variant underlines the compulsion to undertake surveillance following vaccination to track vaccine effectiveness and to look for the appearance of vaccine-escape mutants. SARS-CoV-2 being an RNA virus tends to have a higher mutation rate, but the presence of 23 mutations 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, the extent of international spread is 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.

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