States have continued steadily lifting restrictions, despite warnings from top federal health officials like Dr. Anthony S. Fauci that new coronavirus cases in the United States have plateaued at a very high level after their drastic drop has stalled, and that the country urgently needed to contain the spread of more transmissible variants.
Arizona, California and South Carolina joined a growing list Friday by loosening restrictions, to varying degrees. Arizona’s governor ended capacity limits on businesses, but said they must still require masks. South Carolina’s Republican governor lifted the state’s mask mandate in government buildings, while recommending restaurants continue requiring masking.
California will allow amusement parks and outdoor sports and live events at stadiums to restart on April 1, with reduced capacity and mandatory masks.
“We’ve just now recently experienced the worst surge,” Dr. Fauci said Friday during a White House coronavirus briefing, adding that the country had plateaued at between 60,000 and 70,000 new cases per day. “When you have that much of viral activity in a plateau, it almost invariably means that you are at risk for another spike.”
The seven-day average of new cases was about 61,000 day as of Friday, the lowest average since October, according to a New York Times database. But that number was still close to last summer’s highest peak.
Dr. Fauci warned the United States could be following the same treacherous path that Europe has recently been on.
“They plateaued,” he said. “And now, over the past week, they saw an increase in cases by 9 percent, something we desperately want to avoid.”
He warned that the virus mutates as it replicates, a process that can be extended when immunocompromised people are infected. He said that maintaining masking, hand washing and social distancing was urgent.
The B.1.1.7 variant, first identified in Britain, is spreading so rapidly in the United States that data analysis suggest that, as of this week, it has most likely grown to account for 20 percent of new U.S. cases. And scientists in Oregon have identified a single case of a homegrown variant with the same spine as B.1.1.7 that carries a mutation that could blunt the effectiveness of vaccines.