In a final parting shot, 2020 delivered this bit of late-breaking bad news: A new variant of COVID-19 has emerged that appears more contagious and last week was confirmed in one man in Colorado and another in California.
The strain — known scientifically by letter and number jumbles including SARS-CoV-2 VOC 202012/01, 501Y.V1 or B.1.1.7 — was first detected in the United Kingdom in late September. By November it was the most dominant form of the virus among people infected in Southeast England, which includes London.
Another variant that shares some of the same mutations has been found in South Africa and is also spreading. It emerged independently from the UK strain.
While the news isn’t welcome, experts say it’s also not a shocker.
“This is what viruses do. They try to evolve to enhance their own replication and transmission rates,” said Deborah Fuller, a professor of microbiology in the University of Washington’s Department of Medicine. “It’s not surprising at all.”
With more than 85 million reported COVID infections worldwide, there are hundreds of existing novel coronavirus variants. But the ones that gain attention are those that spread more rapidly.
This summer researchers realized that the original version of COVID had been quickly and largely replaced by a variant called either D614G or 614G. After initial uncertainty, many experts this fall agreed that it was increased transmission that led to its dominance. Now, B.1.1.7 is in the spotlight.
Viruses, like all living things, accidentally and randomly introduce changes into their genetic code as they copy the blueprints of their being and replicate. RNA viruses like SARS-CoV-2 are more prone to incorporating errors than organisms that use DNA to record their instructions because the RNA system doesn’t have the same safeguards for correcting mistakes.
While our understanding of this new, more transmittable variant is evolving, one expert predicted that more than 90% of COVID infections in the UK would be caused by this strain by Feb. 1. Fred Hutchinson Cancer Research Center epidemiologist Trevor Bedford expects it could become the dominant variant in the U.S. by March, according to an interview with the Seattle Times.
With data that has emerged in the last week, I'm now 80-90% convinced that infections by the UK variant virus (Pangolin lineage B.1.1.7, @nextstrain clade 20B/501Y.V1) result in, on average, more onward infections, ie are more transmissible. 1/10https://t.co/g8HKduGvqW
— Trevor Bedford (@trvrb) December 29, 2020
Here’s what else is known about the new COVID variant:
How do we know it’s more contagious?
In the above tweet thread, Seattle’s Bedford points to three lines of evidence that leads him to believe it’s more transmissible:
- The new form quickly became dominant over other variants in the UK.
- It has a higher “secondary attack rate,” which means each case infects more people.
- Infected people appear to have a higher viral load, carrying perhaps 10 to 100 times more virus in their nose and throat.
Initial estimates suggested that the new variant could be a whopping 71% more contagious, but another study said it was 56% more transmissible.
Bedford puts that number lower. He said in a typical COVID exposure (coming within six feet of an infected person for 15 minutes or longer) about 10% of people will get sick, while the new strain could result in 15% of exposed people getting infected. He also added this calculation should be taken “with a grain of salt for the moment.”
What researchers don’t yet know is whether the new variant is better at getting inside of cells and infecting people, which would also help explain its infectiousness.
Does it make you sicker?
The U.S. Centers for Disease Control and Prevention and other experts say there is no evidence that this variant of COVID-19 makes people sicker. Because it spreads more easily, it could infect more people and cause more deaths simply because of increased infections.
There’s an evolutionary logic to this effect. While boosting transmission rates is a boon to a virus, making people severely ill or killing them doesn’t carry the same reproductive perks.
“Viruses don’t want to make their hosts disabled,” Fuller said. “If you’re sick and inside, you’re not spreading [the infection].”
What does this mean for vaccines and testing?
COVID vaccines target several different parts of the spiky proteins on the outside of the coronavirus to trigger an immune response. While the new variant does include changes to the spike, because the vaccines recognize multiple features, multiple mutations in the virus would be required to significantly reduce the vaccines’ performance, said the CDC and others.
“The vaccines were designed with viral evolution in mind,” said Fuller, whose own lab is working on what she calls the second generation of vaccines.
And there’s a limit to how much the spike proteins are likely to change. If they mutate too much, it could impede the virus’ ability to get inside cells.
The vaccines also induce a response from the immune system’s T-cells as a second line of defense, Fuller said. That means if the virus evaded the antibody barrier generated by the vaccine, the T-cells are also primed to recognize the infected cells and destroy them. This is true for both the mRNA vaccines currently in use from Pfizer and Moderna, as well as for adenovirus vaccines like those being developed by Johnson & Johnson and AstraZeneca.
Research is still being done, but an initial result from a lab in Texas suggests that the current vaccines remain effective against the new variant. Bedford and Fuller both guessed that the vaccine could suffer a modest reduction in efficacy, dropping perhaps from 95% to 85%, but said that would not greatly inhibit its performance.
It could, however, shift the benchmark for reaching herd immunity against the virus. That number is determined by how efficacious vaccines are and how transmissible is the virus is. Dr. Anthony Fauci, America’s leading infectious disease scientist, previously gave an immunization rate of 75-85% to achieve herd immunity and protect the public. If the virus spreads more easily, the goal gets higher.
One positive note is that Pfizer and Moderna’s mRNA vaccines are relatively easy to tweak to better match the coronavirus. The companies could swap in different target stretches of mRNA for bolstering immunity, experts said. Biotech companies already do seasonal updates for flu vaccines to mirror viral mutations.
The PCR tests used to detect the COVID virus also target multiple sequences its genetic code, so they too should still be effective.
How do we track it?
Bedford and others are eager for the U.S. to more quickly sequence the virus in infected people in order to better track new variants and their spread. The infected Americans identified in Colorado and California had not been traveling, which suggests that the new strain has been spreading in the U.S. undetected.
The CDC launched the National SARS-CoV-2 Strain Surveillance (NS3) program in November to improve its tracking of viral mutations. The agency expects the effort to become fully implemented this month. The improvements include plans to sequence and characterize each week some 750 virus samples collected from states.
The CDC is contracting with large national reference labs to sequence an additional 1,750 viruses weekly with plans to increase that number, and has additional partnerships and funding available for further tracking.
The UK variant has been found in nearly three dozen countries including Canada, China and numerous European countries, according to the New York Times.
What’s next?
Experts advise that people should continue taking the same COVID precautions that are already proven to reduce spread: wearing masks, maintaining distance between others, washing hands and limiting interactions with people from outside of one’s household. They recommend that everyone who is able receives a vaccination when it becomes available to them.
Washington state has seen a decline in COVID cases recently, with nearly 250,000 confirmed total cases and 3,459 deaths since the start of the pandemic. The number of infections peaked in early December, following the Thanksgiving holiday.
Gov. Jay Inslee recently extended state-mandated restrictions on residents and businesses that are in effect until Jan. 11. They include a prohibition on indoor social gatherings, no indoor dining at bars and restaurants, and other limitations.
