EXPLAINER: Scientists trying to understand new virus variant

Does it spread more easily? Make people sicker? Mean that treatments and vaccines won’t work? Questions are multiplying as fast as new variants of the coronavirus, especially the one moving through England and now popping up in the U.S. and other countries.

Scientists say there is reason for concern and more to learn but that the new variants should not cause alarm.

Worry has been growing since before Christmas, when Britain’s prime minister said the coronavirus variant seemed to spread more easily than earlier ones and was moving rapidly through England. On Tuesday, Colorado health officials said they had found it there.

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

Q: WHERE DID THIS NEW VARIANT 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.

Most changes 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 if it acquires a lot of changes that make it very different from previous versions.

Q: HOW DOES ONE VARIANT BECOME DOMINANT?

A: That can happen if one variant takes hold and starts spreading in an area, or because “super spreader” events helped it become established.

It also can happen if a mutation gives a new variant an advantage, such as helping it spread more easily than other ones...