WHO says Covid is mutating at slower rate than flu as new strain in U.K. appears more contagious

World Health Organization officials said Monday that the coronavirus is mutating “at a much slower rate” than seasonal influenza, even as officials in the U.K. announced this weekend that a new mutation of the virus is allowing it to spread more easily.

Seasonal influenza mutates so often that scientists have to regularly develop new vaccines to inoculate the population against the virus every year. U.K. officials have told the WHO that the Covid-19 vaccines appear to be just as effective against the new strain, but more research is needed. While all viruses naturally mutate, not every mutation makes a virus more contagious or more virulent.

“SARS-CoV-2 is mutating at a much slower rate than influenza,” WHO chief scientist Soumya Swaminathan said at a press briefing. “And so far, even though we’ve seen a number of changes and a number of mutations, none has made a significant impact on either the susceptibility of the virus to any of the currently used therapeutics, drugs, or the vaccines under development, and one hopes that that will continue to be the case.”

WHO officials reiterated that officials from the U.K. have said the new variant could be up to 70% more transmissible than the original strain of the virus. Dr. Mike Ryan, executive director of the WHO’s health emergencies program, said it was unclear if the increase in spread in the U.K. is due to the mutation or human behavior.

“We’ve seen an estimate of a small increase in the reproductive number by the U.K.,” he said, meaning the virus is spreading faster, which could mean it is more contagious or spreads more easily in colder months. It could also mean people are getting lax about following public health protocols. “It remains to be seen how much of that is due to the specific genetic change in the new variant. I suspect some.”

Maria Van Kerkhove, head of the WHO’s emerging diseases and zoonosis unit, said U.K. officials estimate that the mutation has caused an increase in the reproductive rate of the virus from 1.1 to 1.5. That means that each person infected with the variant is estimated to infect another 1.5 people, up from 1.1 when infected with the original variant.

She added that officials are investigating three elements of the new variant. She said scientists are looking into whether it spreads more easily, whether it causes more or less severe sickness, and how the antibody responds to an infection. Van Kerkhove and others emphasized that there does not appear to be any impact on the effectiveness of the Covid vaccines on the new variant.