Over the last week, the daily number of cases and deaths, on average, has risen by about 2% compared to the week prior, CDC Director Rochelle Walensky said during a White House press briefing, to about 67,000 cases per day and 2,000 American lives lost to the virus each day. It's nearly a third of what the U.S. was seeing during its holiday surge, but still no better than what the U.S. saw during the summer peak.
This leveling off comes as states across the country, led by Democrats and Republicans alike, have eased restrictions, from stringent measures put in place during the surge, like stay-at-home orders in California or shutting down indoor dining in New York, to reverting to the loosest rules since the pandemic began, like in Montana and Iowa, where the governors have lifted mask mandates and rolled back restrictions on businesses.
Arkansas and Texas are also considering a repeal of their mask mandates in the coming weeks.
Walensky, previously the chief of Infectious Diseases at Massachusetts General Hospital, had a targeted plea to all states on Monday: "Please hear me clearly. At this level of cases with variants spreading, we stand to completely lose the hard-earned ground we have gained," she said.
"These variants are a very real threat to our people and to our progress. Now is not the time to relax the critical safeguards that we know could stop the spread of COVID-19 in our communities, not when we are so close," she said.
Walensky urged people to continue driving down cases, as the U.S. has mostly done since early January -- though certain areas of the country, like Texas and Florida, have seen upticks in recent weeks.
There is no single reason cases have leveled off, but infectious disease epidemiologist and ABC News contributor John Brownstein said it could be a combination of factors including relaxed mitigation efforts or complacency, but also a drop-off in testing that allows people to unknowingly spread the virus and perhaps the cold snap in southern states like Texas that prompted people to gather indoors.
Brownstein also pointed to the increasing prevalence of the B.1.1.7 variant, which originated in the U.K. and is about 50% more transmissible.
"Clearly there's a lot of enthusiasm to get back to normal and I think we should be trying to do everything we can," Brownstein said. "But certain activities that we know are conducive to transmission, we need to hold off a little longer."
Walensky, chief medical adviser Dr. Anthony Fauci and other public health experts have been warning for weeks that letting up on mitigation before cases reach a more controllable level could lead to the same surge the U.S. saw after a patchwork of reopenings, largely across the South, erased much of the progress of the nearly nationwide March and April shutdown.
"We have the ability to stop a potential fourth surge of cases in this country. Please stay strong in your conviction, continue wearing your well-fitted mask and taking the other public health prevention actions that we know work," Walensky said.
Before news of the plateauing statistics, most of the U.S. was enjoying a sharp downward trajectory that coincided with the approval of a third coronavirus vaccine, developed by Johnson & Johnson and approved by the FDA over the weekend.
On Monday, 3.9 million doses of the newest vaccine, which only requires one dose compared to the double doses required for the Pfizer or Moderna vaccines, shipped out. Sixteen million more doses will be available by the end of March, though the White House prepared states for an uneven distribution in the first few weeks as the company gets their production off the ground.
And as of Monday, 50 million Americans had received at least one dose of the other vaccines available, Pfizer and Moderna, according to the White House.
All three vaccines are safe and efficacious against the virus and its variants, including the B.1.1.7 variant, which was originally discovered in the U.K. The variant is about 50% more transmissible and scientists expect it to be the dominant strain in the U.S. by mid-March, making the race to vaccinate a majority of Americans more urgent.
The White House urged Americans to get whatever vaccine is available to them when it's their turn.
"All three vaccines have been proven safe, highly effective, at preventing severe disease and hospitalizations and death from COVID-19 after full immunity," said Dr. Marcella Nunez-Smith, the chair of the White House health equity task force.
"And if I could leave people with one message, it is this -- get vaccinated. With the first vaccine available to you. Protect yourself, your family and your community from COVID-19," she said.