What Is the B.1.1.7 Variant?

What to know about this COVID-19 mutation

All viruses develop mutations and variants, and COVID-19 is no different. Since the start of the COVID-19 pandemic, multiple variants of the virus have developed. One of these variants is B.1.1.7, which was initially found in the United Kingdom in September 2020. It is now currently the dominant strain in the United Kingdom.

COVID-19 B.1.1.7. variant

Sadik Demiroz / Getty Images

Where B.1.1.7 Has Spread

The B.1.1.7 variant has now spread to over 100 countries worldwide, including the United States. Initially, the virus was spread to other countries by infected travelers from the United Kingdom. It has now become the dominant strain in most European countries. 

Spread in the United States

The B.1.1.7 variant was initially found in the United States in December 2020, with the first case found in Colorado.

Currently, the states with the highest rates of the B.1.1.7 variant include:

  • California
  • Colorado
  • Connecticut
  • Florida
  • Georgia
  • Massachusetts
  • Michigan
  • Minnesota
  • Tennessee
  • Pennsylvania

The variant has now been found in every state and is estimated to soon be the dominant cause of new COVID-19 infections in the United States.

Why Do Viruses Mutate?

It is common for all viruses to mutate. When a virus enters the body, it begins to make copies of itself.

Sometimes during this process, mistakes (mutations) are made in the copies, which can make it easier for the virus to invade the cell. When this same mutation continues to further copy itself, a variant of the virus forms.

Is B.1.1.7 More Contagious?

The B.1.1.7 variant has been found to be at least 50% more contagious than the original COVID-19 virus.

The infectiousness of a virus is measured by a reproduction number—called R0—which measures the number of people an infected person will give the virus to. For example, if the R0 is 1, an infected person is likely to give it to one other person; an R0 of 5 means an infected person is going to transmit it to five other people. We do not yet know the R0 for the B.1.1.7 variant.  

Globally, the R0 for COVID-19 varies, but with the B.1.1.7 variant, the R0 is increased at least 50%, leading to an exponential increase in transmission. 

Preventing Transmission

Precautions to prevent the transmission of the B.1.1.7 variant are the same as for the original COVID-19 virus and should continue to be followed. These precautions include:

• Staying 6 feet apart from others who don’t live in your house

• Wearing a mask that covers your mouth and nose

• Washing hands often or using hand sanitizer  

If you are fully vaccinated, the Centers for Disease Control and Prevention (CDC) has released new guidelines that say it is safe to gather indoors with other fully vaccinated people and to not wear a mask when outdoors, unless it is a crowded setting or venue.

Risk of Reinfection

A study done in the United Kingdom did not demonstrate increased rates of COVID-19 reinfection related to the B.1.1.7 variant.

Is B.1.1.7 More Severe?

Initially, it was thought that the B.1.1.7 variant may cause an increased risk of death.

However, in a study published in April 2021, it was found that the B.1.1.7 variant was not found to be associated with an increased risk of symptoms, severe disease, or death.

The CDC does still state, though, that there is an increased severity based on hospitalizations and case fatality rates.

Will Vaccines Work Against B.1.1.7?

The World Health Organization (WHO) has reported that vaccines from Pfizer/BioNTech and Moderna continue to be highly effective against the B.1.1.7 variant. Vaccines produced in other countries appear to be effective against this variant as well. There is currently little data on the effectiveness of the Johnson & Johnson vaccine against this variant.

Are Kids More at Risk for B.1.1.7?

Studies from the United Kingdom have shown increased numbers of children and young adults being infected with the B.1.1.7 variant. However, this does not mean that children are more at risk for infection of the B.1.1.7 variant.

Studies have found children who become infected have mild symptoms or no symptoms at all, and there is no evidence of increased risk of severe disease or hospitalization in children.

A Word From Verywell

Experts are worried about the spread of the B.1.1.7 variant of COVID-19 around the world and in the United States. As this variant is more contagious, it has the opportunity to spread quickly.

Continuing to follow precautions as recommended by the CDC and getting a vaccine when it is available to you is important to help decrease the spread of this and other variants of COVID-19. 

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.

Was this page helpful?
Article Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Centers for Disease Control and Prevention. Science brief: emerging SARS-CoV-2 variants. Updated January 28, 2021

  2. World Health Organization. Weekly epidemiological update on COVID-19: 13 April 2021. Updated April 13, 2021.

  3. Centers for Disease Control and Prevention. US COVID-19 cases caused by variants. Updated April 10, 2021.

  4. Cleveland Clinic. What does it mean that the coronavirus is mutating? Updated January 11, 2021.

  5. Davies NG, Abbott S, Barnard RC, et al. Estimated transmissibility and impact of SARS-CoV-2 lineage B.1.1.7 in EnglandScience. 2021;372(6538). doi:10.1126/science.abg3055

  6. Center for Disease Control and Prevention. How to protect yourself & others. Updated March 8, 2021.

  7. Centers for Disease Control and Prevention. US COVID-19 cases caused by variants. Updated April 10, 2021.

  8. Graham MS, Sudre CH, May A, et al. Changes in symptomatology, reinfection, and transmissibility associated with the SARS-CoV-2 variant B.1.1.7: an ecological studyThe Lancet Public Health. 2021. doi:10.1016/S2468-2667(21)00055-4

  9. New and Emerging Respiratory Virus Threats Advisory Group. NERVTAG. Updated January 21, 2021.

  10. Frampton D, Rampling T, Cross A, et al. Genomic characteristics and clinical effect of the emergent SARS-CoV-2 B.1.1.7 lineage in London, UK: a whole-genome sequencing and hospital-based cohort studyThe Lancet Infectious Diseases. doi10.1016/S1473-3099(21)00170-5