Mutations in a virus, like in all organisms, are a natural process due to mistakes during replication of genetic material. While most mutations are often inconsequential, some can alter the behaviour of the virus, making it more transmissible or deadlier.
Genome sequencing helps identify these variants and important ones can be broadly placed into three categories.
‘Variants of interest’ have specific mutations that may potentially increase spread or reduce effectiveness of diagnostics, drugs and vaccines. ‘Variants under investigation’ are those that are being studied for their effect on disease spread and medical intervention. Finally, ‘Variants of concern’ (VoC) are those that are found to cause increased transmissibility or mortality or are affecting medical intervention.
Such variants may require a change in strategy for testing and treatment.
What do we know about the new mutant variants in India?
The health ministry said that there are four major variants of the coronavirus that have been found in India—three foreign and a new indigenous one.
The most common of them all is the UK variant—found in 736 people in 18 states. Another 34 people in seven states have been infected with the South African variant, which has been seen reducing vaccine efficacy. One person has been diagnosed with the Brazilian variant which is more transmissible. These three have been categorized as VoCglobally.
Sujeet Kumar Singh, director of the National Centre for Disease Control said indigenous variants “have been around for the past six months" in over 70 districts of the country.
He highlighted six “variants of interest" which have been found in over 100 samples each. Of these, one is particularly being looked at because it has a double mutation—characteristics of two already identified mutants—on the spike protein. The mutants are codenamed L452R and E484Q.
Are these variants responsible for the second coronavirus wave in Maharashtra?
Singh said that evidence collected from genomic sequencing of samples shows that none of the variants—foreign or indigenous—are responsible for the latest surge in covid-19 cases.
The largest proportion of the double mutant variant was found in Nagpur, where around 20% of samples tested positive for it, indicating that the bulk of the spread was not through the mutant strain.
The government said the rise in cases is being found in clusters that did not see a large number of cases in the first wave and attributed the new wave to people failing to adhere to covid-appropriate measures like wearing masks properly and social distancing.
Will the double mutant variant affect the efficacy of vaccines?
Studies about the effect of the variant on vaccines are ongoing. In other variants found abroad, both the mutations found in the double mutant have been seen increasing infectivity or evading immune response.
In a report by health and science-based news website Down To Earth on Wednesday, Pune’s National Institute of Virology said the E484Q mutation can possibly escape antibody neutralization while L452R can increase the rate of transmission.
The National Institute of Virology is currently trying to isolate the mutant virus to conduct tests, the report said.
Studies about the effect of the variant on vaccine efficacy are initially done through in-vitro methods—where the virus is tested in the blood serum of vaccinated individuals to determine whether antibodies can neutralize it. A more accurate way is to conduct human trials but these can be onerous and the results take months.
What can we do to prevent catching these mutant strains?
The answer from the experts and the government is common—strictly follow covid-appropriate measures like social distancing, wearing masks and basic hygiene—and vaccinate yourself. These will reduce not just the spread of the disease, including through new variants, but also provide fewer opportunities for the virus to mutate.
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