Scary new COVID-19 strain means we must move faster

Every virus mutates. But the longer it is allowed to multiply, the more mutations it accumulates and the better the odds it will learn to evade detection.

That’s why, especially in the face of worrisome new COVID-19 viral variants, a fast and effective vaccination campaign is so essential.

“The take-home message is that we’re really in a race now, and really this only increases our urgency to mass vaccinate the population and protect the population before additional variants may evolve and emerge,” said Dr. Charles Chiu of UC San Francisco, whose lab is collaborating with the state’s Department of Public Health to seek and sequence viruses.

Scientists are especially worried about the mutation in a coronavirus variant called L452R, which comes on the heels of the another strain from the United Kingdom that is now spreading rapidly in the United States.

Why the worry? Location, location, location. As in real estate, the whereabouts of a virus’s mutation can make or break its significance.

The variant, now linked to multiple outbreaks in California, including large ones in Santa Clara County, has a key change in the genetic instructions for its so-called “spike protein,” which the virus uses to enter our cells — and which is the target of our only two vaccines.

It’s not yet proved that this new mutation makes the virus more transmissible, or that it evades vaccines.

But it lives in a dangerous neighborhood. And it’s making the virus act in suspect ways. Only a month or so ago, this strain of the virus was pretty uncommon. Now it represents about one-quarter of all new cases that undergo genomic sequencing.

To find out, scientists are now growing the virus in a lab in San Francisco, then watching how it behaves. Eight samples of the variant COVID-19 strain, from eight different people, are being cultured. Then these viruses will be injected into samples of human blood of people who have vaccinated, or unvaccinated, to see if they proliferate.

It’s well known that as a virus replicates, it sometimes makes random mistakes, called mutations, in its genetic code.

So far, we’ve been lucky. Unlike flu viruses, the COVID-19 virus is typically quite stable, accumulating just one or two mutations a month. That’s because it has a protein that acts as a proofreader, correcting as many errors as it can find. And when it does change, most of the resulting variants are benign or even weakened versions of the pathogen.

But there have been several notable changes during the course of the pandemic.

One of the first variants, a mutation called D614G that boosts infectivity and transmission, appeared in China last March. Now it’s the dominant form of the virus, seen in 99% of all cases worldwide. This mutation — in the spike protein — is blamed for the explosion of the pandemic.

Another change in the virus, a deletion in the genetic code, reduces the reliability of our tests. That’s dangerous. Rather than testing positive, a sick person tests negative, so they don’t realize their risk.

Yet another variant, first found in the U.K., has 23 distinct differences compared with what’s currently circulating. One of these changes, a mutation in the spike protein called B117, makes it 50% to 74% more contagious.

While this B117 virus is not more deadly than the existing strain, it could be more difficult to contain. In fact, more than 30 other countries have now spotted the variant, including the U.S. The good news is that it can be stopped by our vaccines. But its ease of spread suggests that we’ll have to vaccinate more people to achieve so-called “herd immunity.”

A more worrisome variant, called B1351 and announced by South Africa on Dec. 18, has eight to 10 mutations for the spike protein. Based on the explosion of cases in South Africa, experts suspect that one of these mutations is making it more transmissible. It has been detected in 20 countries, but not yet the U.S., according to the World Health Organization.

And, what’s worse, a different mutation in that strain seems to reduce the ability of antibodies to fend off the virus — which could limit the effectiveness of vaccines.

“The laboratory data is quite worrisome for the possibility,” said Chiu.

If the virus continues its uncontrolled reproduction, the pandemic could become more contagious, more deadly or harder to vaccinate against, experts say.

“We need to continue to do all of the things we’ve been asking the public to do,” said California’s state epidemiologist Dr. Erica S. Pan.

“Watch your distance, wear a mask, stay home and away from mixing with others,” she said. “And when vaccine is available to you, get it.”