These coronavirus variants are keeping scientists awake at night - CNN

While some of the new variants appear to have changes that look like they could affect immune response, it's only by a matter of degree.

B.1.1.7

At the top of the list for researchers in the US is the B.1.1.7 variant first seen in Britain.

It doesn't cause different rates of hospitalization or mortality," Gregory Armstrong, who directs the Office of Advanced Molecular Detection at CDC, told CNN.

"As far as we know it is transmitted in exactly the same way."

That means the same measures already known to reduce spread will also stop the new variants: mask use, social distancing, avoiding large groups or crowds and frequent handwashing.

The mutations in the variant help it enter cells more easily -- which means if someone, says, breathes in a lungful of air that has virus particles in it, those particles are going to be more likely to infect some cells in the sinuses or lungs rather than bouncing off harmlessly.

"Contacts of people with B.1.1.7 would get sicker at higher rates."

Plus there's evidence people infected with the B.1.1.7 variant have what's known as a higher viral load -- they have more virus reproducing in their bodies.

More infected cells equal more virus.

But Armstrong discounts initial worries that the new variant infects children more easily.

Britain left schools open during the lockdown that saw B.1.1.7 spread, he said, and that would easily explain why more children became infected.

All this simply means people need to try harder to prevent spread until vaccination can be sped up.

"In order to interrupt transmission, we are going to need higher rates of what we do to slow transmission," Armstrong said.

"Hope I'm wrong."

So far, CDC has reports of 120 cases of people infected with B.1.1.7 in 20 states, although the agency says it's likely far more common than that.

"And it may have been circulating in the US for close to two months before it was first detected, on 29 December 2020."

B.1.351

A variant first seen in South Africa called B.1.351 or 501Y.V2, has a different pattern of mutations that causes more physical alterations in the structure of the spike protein than B.1.1.7 does.

Vaccine makers and academic researchers are testing samples of this variant, along with others, to see if it can evade the immune response caused by vaccination.

Dr.

If a particular strain happens to be circulating when transmission increases because of human behavior, that strain will ride along and become more common not because it spreads more easily, but simply because it was there.

In a pre-print -- a study that's posted online but not reviewed by a medical or scientific journal -- a team at Cedars-Sinai in Los Angeles said they found this variant in 36% of samples taken from 192 patients at the hospital in late November and December, and in 24% of samples from southern California

The California Department of Public Health said the variant was "increasingly" turning up around the state.

Right now the US is doing a poor job of what's known as genomic surveillance, Armstrong said.