En español | Public health officials are monitoring new strains of the coronavirus that are more contagious, worrying experts who say they could lead to a surge in COVID-19 cases and delay the country’s recovery from the pandemic.
Studies show the variants are 50 to 70 percent more transmissible than the original coronavirus.
Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases and President Biden’s chief medical adviser, has said the best way to combat variants is to vaccinate as many people as possible quickly and to continue precautions such as social distancing and wearing a mask. “Viruses can’t mutate unless they replicate,” he said.
The U.S. Centers for Disease Control and Prevention (CDC) is tracking the following variants:
- B.1.1.7.: First discovered in the United Kingdom, B.1.1.7 is now circulating in almost every U.S. state, and the CDC predicts it will become the dominant strain in the U.S. by April. A peer-reviewed study published March 10 found that the variant has a significantly higher death rate than the original strain.
- B.1.351: This variant was first identified in South Africa and is in at least 24 U.S. states. It concerns scientists because it contains a mutation that could allow the virus to elude some of the antibodies produced through vaccines.
- P.1: First discovered in Brazil, this variant is in at least nine U.S. states. Studies of its spread in the Brazilian city of Manaus indicate it may have the ability to reinfect people who were previously infected with the original strain.
- Homegrown variants: Researchers are paying attention to several other concerning variants that originated in the U.S., including B.1.526 in New York City and B.1.427/429 in California.
How did these new COVID-19 strains develop?
Because viruses multiply rapidly, new mutations are always occurring, said William Schaffner, M.D., an infectious diseases specialist at Vanderbilt University Medical Center in Nashville and medical director of the National Foundation for Infectious Diseases (NFID).
Most of these tiny genetic changes have no effect on the behavior of the virus.
The new variants the CDC is tracking stood out because they spread more easily, Schaffner said, so they can rapidly replace other versions of the virus and become dominant.
Are the new strains more dangerous?
A peer-reviewed study published in the journal BMJ on March 10 found that people infected with the B.1.1.7. variant from the U.K. are 32 to 104 percent more likely to die than those infected with the original strain.
It’s not clear yet if the other variants are associated with more severe illness.
Because variants are more contagious, they may also be able to infect more people more quickly, potentially increasing overall hospitalization and death rates.
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Will the COVID-19 vaccines work against the new strains?
Early studies indicate all three authorized COVID-19 vaccines — made by Moderna, Pfizer-BioNTech and Johnson & Johnson — work well against B.1.1.7, the variant first discovered in the U.K.
The variants first found in Brazil and South Africa are more of a question mark, Schaffner said, because they contain a mutation that may allow the virus to elude some of the antibodies produced through vaccines.
The vaccine manufacturers are working to create booster shots and updated versions of their shots to improve protection against those variants.
What precautions should you take?
The guidance about how to protect yourself from COVID-19 hasn’t changed: Wear a mask, wash your hands, practice social distancing, avoid crowds and stay home if you can.
“These strains reinforce the importance of all of the standard interventions we’ve been talking about, because they work,” Schaffner said. “And when it comes your turn to get the vaccine, by all means get the vaccine.”
Editor's note: This story, originally published on Jan. 8, 2021, has been updated with new information.