Several US states, many of them governed by Democrats, began rolling back mask mandates this week, a move public health experts warn could set back progress battling Covid.

On Wednesday, Massachusetts, Illinois, New York and Rhode Island joined California, Connecticut, Delaware, New Jersey and Oregon in lifting mask mandates for some public places.

The wave of relaxations comes after months of private meetings among state leaders and political focus groups after the November elections, according to reports. “Now, it’s time to give people their lives back,” Sean Maloney, chair of the Democratic Congressional Campaign Committee, tweeted in support of New York suspending its indoor mask-or-vaccine mandate.

Yet the lifting of rules has not been universally applauded and is coming at a time when the vast majority of the country (99%) is still seeing high transmission of the virus, according to the US Centers for Disease Control and Prevention (CDC). Public polls show consistent support for mask mandates and other precautions, and experts say the time to relax precautions is not here yet – and acting prematurely could prolong this wave.

“In my view, it’s too soon. I feel like we’re anticipating too much,” said Justin Lessler, a professor of epidemiology at the UNC Gillings School of Global Public Health. “We’re being too confident that things are going to keep going the direction that they have been going.”

The CDC’s director Rochelle Walensky also recently said that “now is not the moment” to drop masks in public, although the agency is reportedly weighing changes to its guidance on masks.

While Covid cases have dropped from Omicron’s record-shattering peak, the US still has an average of more than 230,000 cases each day – similar to the height of last winter’s wave – and more than 2,300 people are dying from Covid each day, according to the CDC. While hospitalizations are beginning to fall, 80% of hospitals are still under “high or extreme stress”.

Treatments, including antivirals and monoclonal antibodies, that keep Covid from progressing to serious illness and death are still in short supply throughout the country. Children under the age of 5 are not yet eligible for vaccines, while less than a quarter of kids ages five to 11 are fully vaccinated.

“We have hundreds of thousands of people dying, we have millions who’ve been hospitalized and we have an unknown number who have long Covid and who will get long Covid as we roll back what little mitigation we have,” said Julia Raifman, assistant professor at Boston University School of Public Health and creator of the Covid-19 US state policy database.

“Saying things are normal undercuts us in getting more people vaccinated and in helping people wear masks, because transmission actually remains quite high,” Raifman said. “The best way to help people think things are more normal is to reduce the amount of virus with the mitigation measures that we have.”

The failure to set measures on when to drop or reinstate precautions “starts from the top”, including the CDC and the White House, Raifman said. “The whole of the pandemic response is being mismanaged, and only better leadership can help us come together to better address it.”

Anthony Fauci, the president’s chief medical adviser, says the US is leaving the “full blown” phase of the pandemic. In September, he said controlling the pandemic meant having fewer than 10,000 cases a day.

“This is not a declaration of victory as much as an acknowledgment that we can responsibly live with this thing,” said the New Jersey governor, Phil Murphy, who is also a key leader of the National Governors Association. Governors have reportedly urged Biden to “move away from the pandemic”.

Many states – including Connecticut, Delaware, Massachusetts, Oregon, New Jersey and Rhode Island – are also set to lift school mask mandates. California is considering changes to the rules on school masks, while Illinois and New York will keep theirs for now. The governor of Pennsylvania lifted the school mask rule last month.

Teachers’ unions have joined health experts in calling for science-based recommendations in order to keep educators and students safe, and to keep the virus from forcing further school closures caused by worker shortages.

“I worry about taking off measures just because cases are trending down,” Lessler said. “At least some of the rate of decrease has to do with what little we’re doing to try to control transmission, and by stopping these measures – both directly and in the message it sends about the risk of the virus – you slow that down-trend.”

A new variant could also emerge and change the situation yet again, he said. “We’ve time and time again been surprised by new variants.”

Lifting measures too early and slowing the decrease in cases can result in “a lot of unnecessary cases and deaths that you might have avoided simply by waiting a few weeks”, Lessler said.

“And if we change what we’re doing substantially, we may not get there, or it may take us longer to get there than anticipated.”