The head of the US Centers for Disease Control and Prevention said on Sunday it is "absolutely" too soon to lift mask mandates, citing daily Covid-19 case numbers that despite recent declines remain more than double the levels seen last summer.
Dr Rochelle Walensky's warning that face-covering requirements are still critical came just days after governors in Iowa and Montana lifted long-standing mask mandates in their states.
Appearing on NBC's "Meet the Press," Walensky said preventing further surges of infection is key to safely reopening schools and regaining some level of social normalcy until collective Covid-19 immunity can be achieved through mass vaccinations.
Whether Americans can look forward to walking down the street without wearing a mask by the end of the year "very much depends on how we behave right now," she said.
Asked if it was still too early for states to eliminate rules requiring the use of face masks in public, Walensky replied, "Absolutely."
While Covid-19 infection rates and hospitalizations appear to be waning, the United States has a long way to go before it can safely return to a mask-less normal, she said.
"The cases are more than two-and-a-half-fold times what we saw over the summer," said Walensky, who was sworn in as CDC director last month after President Joe Biden took office. "It's encouraging to see these trends coming down but they're coming down from an extraordinarily high place."
Health experts say population-wide mask-wearing is one of the most effective ways of pushing Covid-19 transmission down to controllable levels.
Continued adherence to social distancing and face coverings remains especially urgent given the risks posed by new coronavirus variants found to be more transmissible, and possibly more resistant to antibodies, than the original strain.
Covid-19's grip on the United States remained strong on Sunday, with 27.6 million cases confirmed and more than 484,600 lives lost to the highly contagious respiratory virus to date, according to a Reuters tally.
The US inoculation campaign has gained considerable momentum since a sluggish start in December, with 52.9 million total vaccines administered so far, according to the CDC.
As the United States continues wrestling to ramp up vaccine supplies and distribution, an unusually broad swath of wintry weather in recent days caused the latest setback, forcing mass vaccination centres from Texas to Virginia to suspend operations.