Scientists urge concern, not alarm over new virus strains

Does it spread more easily? Make people sicker? Mean that treatments and vaccines won’t work? Questions are multiplying as fast as new strains of the coronavirus, especially the one now moving through England. Scientists say there is reason for concern but that the new strains should not cause alarm.

“There’s zero evidence that there’s any increase in severity” of COVID-19 from the latest strain, the World Health Organization’s emergencies chief, Dr. Michael Ryan said Monday.

“We don’t want to overreact,” the U.S. government’s top infectious disease expert, Dr. Anthony Fauci, told CNN.

Worry has been growing since Saturday, when Britain’s prime minister said a new strain, or variant, of the coronavirus seemed to spread more easily than earlier ones and was moving rapidly through England. Dozens of countries barred flights from the U.K., and southern England was placed under strict lockdown measures.

Here are some questions and answers on what’s known about the virus so far.

Q: WHERE DID THIS NEW STRAIN COME FROM?

A: New variants have been seen almost since the virus was first detected in China nearly a year ago. Viruses often mutate, or develop small changes, as they reproduce and move through a population — something “that’s natural and expected,” WHO said in a statement Monday.

“Most of the mutations are trivial. It’s the change of one or two letters in the genetic alphabet that doesn’t make much difference in the ability to cause disease,” said Dr. Philip Landrigan, a former Centers for Disease Control and Prevention scientist who directs a global health program at Boston College.

A more concerning situation is when a virus mutates by changing the proteins on its surface to help it escape from drugs or the immune system, or...