The recent infectious wave in the UK, prompting fresh lockdown measures, is associated with a mutant variant of the SARS CoV 2 called N501Y. Mutation occurs due to changes in the genetic sequence of the virus, which in the case of SARS CoV 2, is the RNA. This happens due to mistakes that occur when the virus is replicating. If the mutation causes significant changes to protein structure, it could alter course of the disease.