What is B.1.1.7 and why is it in Colorado?

A new strain of coronavirus is in the Centennial state. What does it mean?

December 31, 2020 6:00 am

Dr. Francis Collins, Director of the National Institutes of Health, holds up a model of COVID-19 during a U.S. Senate Appropriations subcommittee hearing on the plan to research, manufacture and distribute a coronavirus vaccine, known as Operation Warp Speed, July 2, 2020, on Capitol Hill in Washington, D.C. (Saul Loeb-Pool/Getty Images)

On Tuesday afternoon, Gov. Jared Polis announced the first documented case of a novel strain of coronavirus in Colorado. Word spread quickly, prompting many questions: How did it get here? What is B.1.1.7? Will it impact vaccines? Is it more infectious?

Here’s what we know from the science so far.

The new strain — dubbed B.1.1.7 for short — reflects recent findings of multiple mutations within SARS-CoV-2, the virus that causes the disease COVID-19. Specifically, these variants fall under the B.1.1.7 lineage on the virus’s genetic tree, hence the nickname. Scientifically, the new strain is denoted as SARS-CoV-2 VUI 202012/01. This acronym — which could easily replace any vehicle identification number — stands for the first variant under investigation in December 2020.

A critical distinction is that while this is the first variant of interest, it is in no way the first variant detected — and it certainly won’t be the last. This is normal.


As a general rule, viruses mutate. Often, these mutations do not create significant effects. Other times, the type of mutation can alter the way a virus behaves, such as how infectious it becomes, or the severity of symptoms it can produce. Since the start of the pandemic, SARS-CoV-2 has mutated on average roughly once every two weeks. To date, these changes have been insignificant, with no known increases in transmissibility or symptoms. As such, they were largely not reported.

Since the start of the pandemic, SARS-CoV-2 has mutated on average roughly once every two weeks.

In contrast, the B.1.1.7 lineage, identified in the United Kingdom, is potentially significant because of two key factors: A Dec. 23 report found the strain may be 56% more infectious than the original strain (slightly down from a Dec. 18 report at 71%), and the rate and type of mutations are the most divergent since the start of the pandemic.

Right now, the B.1.1.7 strain has been associated with 23 genetic variants as tested across 1,623 genomes, mostly from the United Kingdom. Of these mutations, 17 appear to have altered or deleted amino acids that change the way proteins are encoded. This basically amounts to a kind of spelling error, and may have ranging effects.

One variant is in N501Y. This has previously been shown to increase binding to angiotensin-converting enzyme 2 (ACE2) receptors in humans, which is how the virus initially gains entrance to the body. We don’t yet know if tighter binding will lead to clinical changes, which is why it needs to be monitored. Thus far, there do not appear to be documented increases in hospitalizations or death rates — a promising, but early, sign.

Another eight of these mutations have occurred on the spike — or “S” — protein of the virus. These, too, have prompted further study, as the spike protein is responsible for two roles: Recognizing and binding to the ACE2 receptor, and initiating the virus’ cell membrane to fuse. Also, the spike proteins are a prime target for both testing and modRNA vaccines

ICU nursse Alyssa Golinvaux, center, reacts, as she and others wait before getting the first round of COVID-19 vaccines at UCHealth Poudre Valley Hospital on Dec. 14, 2020, in Fort Collins. (Helen H. Richardson/The Denver Post, Pool)

To this end, the World Health Organization has issued notice to laboratories running diagnostic polymerase chain reaction (PCR) assays — the most accurate COVID-19 test — to be aware that changes to the spike proteins may make identifying the B.1.1.7 strain more difficult. Fortunately, many laboratories already use PCR tests that detect the virus using multiple portions of genetic code, only one of which targets the newly mutated S gene. This means these laboratories can continue to identify SARS-CoV-2 while simultaneously distinguishing the B.1.1.7 strain by results with one less piece of genetic code identified.

Regarding vaccine efficacy, of the roughly 1,270 amino acids in the spike protein, only eight or nine were mutated. While these mutations may still have impact, given the large variety of antibodies our immune system is able to generate to such a broad target, it’s unlikely these mutations will significantly affect the efficacy of currently authorized vaccines.

This does not, however, rule out future mutations which could make vaccines less effective. While the vaccine technology itself is highly flexible — modRNA designs can be updated to reflect a new strain in mere weeks — the current FDA authorization and approval process would likely mandate new clinical trials to demonstrate efficacy, causing lengthy and expensive delays. This may prompt consideration of new interpretations regarding vaccine correlates to reflect new modRNA technology.

All of this still raises the question, how did B.1.1.7 wind up in Elbert County if it originated in the United Kingdom and the first known local patient has no known travel history?

Unfortunately, given the high rate of transmission and continued travel between nations, the new variant was already expected to be in the United States. Most likely, the Colorado case merely confirms existing community spread, particularly as a second case is already suspected. The Centers for Disease Control and Prevention also notes the United States has only sequenced genomes of 51,000 of 17 million cases to date, lagging well behind other nations, and increasing the probability of other B.1.1.7 cases having been missed. Beginning in January, the CDC’s website highlights that states will begin a new program to increase identification of mutated strains.

Meanwhile, wearing masks, physical distancing and getting vaccinated as soon as possible have become all the more critical to preventing further spread of COVID-19.


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Trish Zornio
Trish Zornio

Trish Zornio is a scientist, lecturer and writer who has worked at some of the nation's top universities and hospitals. She’s an avid rock climber and was a 2020 candidate for the U.S. Senate in Colorado.