Health and Science

CDC director warns Covid variants could reverse the recent drop in cases and hospitalizations

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Key Points
  • New variants are a "threat" to the U.S. and could reverse the recent declines in Covid-19 cases and hospitalizations, CDC Director Dr. Rochelle Walensky said Monday.
  • "Please continue to wear a mask and stay 6 feet apart from people you don't live with. Avoid travel, crowds and poorly ventilated spaces and get vaccinated when it's available to you," she added.
Dr. Rochelle Walensky, director of the Centers for Disease Control and Prevention.
Chip Somodevilla | Getty Images

New, highly contagious variants of the coronavirus are a "threat" to the United States and could reverse the recent drop in Covid-19 cases and hospitalizations, the head of the Centers for Disease Control and Prevention warned Monday.

The U.S. reported a seven-day average of 119,900 new Covid-19 cases a day last week, down nearly 20% from the prior week but still "dramatically higher" than the peak seen during the summer, CDC Director Dr. Rochelle Walensky told reporters during a White House news briefing on Covid-19.

The nation also reported an average of 9,977 Covid-19 hospitalizations a day last week, down at least 17% from the prior week, she said.

"The continued proliferation of variants remains a great concern and is a threat that could reverse the recent positive trends that we are seeing," Walensky said. "Please continue to wear a mask and stay 6 feet apart from people you don't live with. Avoid travel, crowds and poorly ventilated spaces and get vaccinated when it's available to you," she added.

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The effectiveness of vaccines against Covid-19 variants

U.S. health officials, including Dr. Anthony Fauci, have expressed concerns about the Covid mutations that could potentially evade the protection of vaccines currently on the market. Moderna, Johnson & Johnson and Novavax have already said their vaccines may be less potent against B.1.351, the highly contagious strain found in South Africa.

On Sunday, South Africa Health Minister Zweli Mkhize said the country would suspend use of AstraZeneca's Covid-19 shot in its vaccination program after data showed it gave minimal protection against B.1.351, the emerging strain there. He said the government would await advice from scientists on how best to proceed following the disappointing results from a trial conducted by the University of the Witwatersrand.

As of Sunday, the CDC has identified 690 cases of the B.1.1.7 variant first identified in the U.K., Walensky told reporters Monday. The agency has identified six cases of the South African strain as well as three cases of P.1, a variant first identified in travelers from Brazil.

Walensky said public health officials are working to find more cases of these variants, adding that federal and state officials over the last three weeks have increased genome sequencing about tenfold. "We are anticipating we might find more" cases in the coming weeks, she added.

The U.S. is always working to find out exactly how contagious and deadly the new strains are, said Fauci, the nation's leading infectious disease expert.

U.K. Prime Minister Boris Johnson said last month that early data suggests that country's strain may be more deadly. Fauci said Monday that there is currently no data to indicate the virus is mutating into a "less virulent" strain, meaning less harmful than the original virus.

The data from the U.K. still "needs to be confirmed," Fauci added. "But thus far, no evidence that it is less virulent. Sometimes when viruses mutate to spread more efficiently, they become less virulent, but we do not have any data to indicate that is in fact happening."

Meanwhile, Fauci has been pushing for people to get vaccinated as quickly as possible, saying last week that the virus cannot mutate if it can't infect hosts and replicate.