Healthcare COVID-19 variant: Current vaccines may not have 100% impact on new strain, says Maha Task Force Head Updated : December 23, 2020 03:15 PM IST Even a minor change in the mutated COVID-19 strain could challenge the efficacy of the vaccines which are recently developed, he said. He also said mass gatherings, like weddings or other functions attended by hundreds of people, are acting as super spreaders and should be avoided.