Every virus mutates. However, the longer it can multiply, the more mutations it accumulates and the better the chances of learning to escape detection.
That is why, especially in the face of worrying new viral variants of COVID-19, a fast and effective vaccination campaign is so essential.
“The message to take home is that we are really in a rush now, and it really only increases our urgency to vaccinate the population en masse and protect the population before other variants can evolve and emerge,” said Dr. Charles Chiu, from UC San Francisco, whose laboratory is collaborating with the State Department of Public Health to search for and sequence viruses.
Scientists are especially concerned about the mutation in a variant of the coronavirus, called L452R, which comes on the heels of another strain in the UK that is now spreading rapidly in the U.S.
Why to worry? Location, location, location. As in the housing market, the location of a virus mutation can make or break its importance.
The variant, now linked to several outbreaks in California, including large ones in Santa Clara County, has a fundamental change in the genetic instructions for its so-called “peak protein”, which the virus uses to enter our cells – and which is the target of our only two vaccines.
It is not yet proven that this new mutation makes the virus more transmissible, or that it avoids vaccines.
But he lives in a dangerous neighborhood. And it is causing the virus to act in suspicious ways. Just a month or so ago, this strain of the virus was quite unusual. It now accounts for about a quarter of all new cases undergoing genomic sequencing.
To find out, scientists are now cultivating the virus in a laboratory in San Francisco, and then watching how it behaves. Eight samples of the variant strain COVID-19, from eight different people, are being grown. These viruses will then be injected into human blood samples from people who have been vaccinated, or not, to see if they proliferate.
It is well known that, as a virus replicates, it sometimes makes random errors, called mutations, in its genetic code.
So far, we’ve been lucky. Unlike influenza viruses, the COVID-19 virus is usually quite stable, accumulating only one or two mutations per month. That’s because it has a protein that acts as a proofreader, correcting any errors it finds. And when it does, most of the resulting variants are benign or even weakened versions of the pathogen.
But there were several notable changes during the course of the pandemic.
One of the first variants, a mutation called D614G. which increases infectivity and transmission, appeared in China last March. It is now the dominant form of the virus, seen in 99% of all cases worldwide. This mutation – in the peak protein – is responsible for the explosion of the pandemic.
Another change in the virus, an exclusion in the genetic code, reduces the reliability of our tests. This is dangerous. Instead of testing positive, a sick person’s test is negative, so they don’t realize their risk.
Yet another variant, found for the first time in the UK, has 23 distinct differences compared to what is currently circulating. One such change, a mutation in the spike protein called B117, makes 50% to 74% more contagious.
Although this B117 virus is no more deadly than the existing strain, it can be more difficult to contain. In fact, more than 30 other countries have already identified the variant, including the United States. The good news is that it can be stopped by our vaccines. But its ease of dissemination suggests that we will have to vaccinate more people to achieve so-called “herd immunity”.
A more worrying variant, called B1351 and announced by South Africa on December 18, has eight to 10 mutations for the protein spike. 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 in the United States, according to the World Health Organization.
What’s worse, a different mutation in this strain appears to reduce the ability of antibodies to defend against the virus – which could limit the effectiveness of vaccines.
“Laboratory data is very worrying about the possibility,” said Chiu.
If the virus continues its uncontrolled reproduction, the pandemic could become more contagious, more deadly or more difficult to vaccinate, experts say.
“We need to continue doing all the things we asked the public to do,” said California state epidemiologist Dr. Erica S. Pan.
“Watch out for distance, wear a mask, stay home and away from mixing with other people,” she said. “And when the vaccine is available to you, get it.”