After a punishing fall that left hospitals struggling, some Midwestern states are seeing a decline in new coronavirus cases. But the signs of improvement are offset by the infection’s accelerating spread on both coasts.

States including Iowa, Michigan, Minnesota and Nebraska have seen decreases in the number of people testing positive for COVID-19 over the past couple of weeks. All, however, are still experiencing an alarming number of deaths and hospitalizations because of the earlier surge of cases.

With winter weather driving people indoors, where the virus spreads more easily, there’s no guarantee the improving dynamic can be maintained, doctors and public health officials say.

“We have a vaccine rolling out, but that doesn’t change the overall picture,” Dr. James Lawler with the University of Nebraska Medical Center’s Global Center for Health Security told the Omaha World-Herald. “Things could still turn south pretty easily.”

But he and others are encouraged by the figures. In Iowa, for example, the number of new virus cases reported daily has declined over the past two weeks from nearly 1,800 to about 1,250. In Nebraska, it has gone from about 1,800 a day to a little under 1,300.

“I am fingers crossed right now,” said Dr. Stacey Marlow, an emergency room physician at UnityPoint Allen Hospital in Waterloo, Iowa. The COVID patients that I am seeing are very, very sick. But there are … less of them.”

Deaths from the virus in Iowa have continued to rise sharply, to an average of 79 a day, up from 28 two weeks ago.

The hope, of course, is that the drop in infections will translate into a decline in deaths, but that could take a few weeks. Many of those now dying of COVID-19 may have been infected weeks ago.

Nationwide, the death toll has topped 300,000, with more than 16 million confirmed infections. On average, the U.S. is seeing about 2,400 deaths and over 215,000 new cases per day. An influential model from the University of Washington says deaths could total 502,000 by April 1, even with a vaccine.

Lawler said more Nebraska residents appear to be following warnings to limit dining out and wear masks in public. It helps that a number of Nebraska cities recently passed mask mandates, he said.

But he said it’s important for Nebraskans to remain vigilant about maintaining social distancing as they wait for vaccines to become widely available in the spring.

In a call with governors this week, White House coronavirus task force member Dr. Deborah Birx said the progress in Midwestern states is being offset by a “deteriorating situation” on both coasts.