Kolkata: Might need new booster shots to fight Mu, 4 other strains: Experts

Kolkata: Experts endorsed the stricter screening of passengers arriving in India from countries where the Mu and four other new Covid variants have been detected, pointing out that the third wave could be dangerous if these strains turned out to be virulent enough or genetically different from the existing ones. This, they felt, could add to the threat from existing variants, which could bypass the vaccines, necessitating new booster doses for them.

Mu and the other four variants—Eta, Iota, Kappa and Lambda—were, however, still “variants of interest” and were yet to be classified as “variants of concern” by WHO, said Peerless Hospital microbiologist Bhaskar Narayan Chaudhuri. “Delta and Delta Plus remain most virulent for they are not preventable by existing vaccines. The new variants, including Mu, are under study and there is yet no proof that these could cause severe infection or are quickly transmissible. Initial reports suggest at least Mu is preventable by a vaccine like Covishield,” said Chaudhuri. But the jury was still out on Mu, said Chaudhuri, adding if it did turn out to be highly transmissible or affected the lungs, then it’s a major worry. “This will be a third one that can evade vaccine immunity,” he said.

Mu has genetic differences with the other known variants, some initial studies say and is causing infections in multiple countries. What makes Mu a matter of concern is that it has what the WHO calls a “constellation of mutations that indicate potential properties of immune escape”. “We need to guard against all new variants. Whether it can penetrate our vaccine-immunity or not will be known once its clinical profile and gene sequencing have been done. If Mu is indeed a constellation of mutations, then it is going to be a threat, like Delta, possibly a bigger one if it’s got multiple properties that are not resisted by our vaccines. In that case, we not only need to screen those arriving from countries where it has been detected but also explore the possibility of a new vaccine that will work against the new variants,” said RN Tagore International Institute of Cardiac Sciences intensivist Sauren Panja.

Studies don’t rule out the possibility that Mu’s genetic changes might make it more transmissible, allow it to cause more severe disease and escape the immune response driven by vaccines or infection with previous variants, according to initial studies. This, in turn, might make it less responsive to treatments.

But existing vaccines will still offer significant resistance to all variants, said CMRI Hospital director of pulmonology Raja Dhar. “The degree of severity will be less for the vaccinated, whatever be the variant. But we now need to develop booster doses that will resist the new strains and are different to the ones that we have. Much like the influenza vaccine, which is altered every year according to the strain, Covid vaccine, too, needs to evolve,” said Dhar.