Amid signs of improving US coronavius situation, hot spots like Michigan are a warning sign.

In a spring of hope, Michigan is a reminder that the Covid winter has yet to pass

Americans have entered a disconcerting phase of the pandemic.

They are awash in hopeful news: With more than 2.8 million shots on average being administered every day, the country is fast approaching universal vaccine eligibility for all adults.

And then there are problems like Michigan.

In a rural stretch of the state along the shore of Lake Huron, coronavirus outbreaks are ripping through churches, schools and restaurants. For more than a week, ambulances have taken several hourlong trips each day to rush Covid-19 patients to I.C.U.s in Detroit, Port Huron or Saginaw.

Even as the pandemic appears to be waning in some parts of the United States, Michigan is in the throes of one of the most alarming outbreaks in the country.

“I never thought we would see this at this time — I thought we would be over the hump,” said Ann Hepfer, a health officer for two counties.

For all the encouraging developments, Americans are getting increasingly ominous warnings about the national picture from public health officials.

On Monday, Dr. Rochelle Walensky, the director of the Centers for Disease Control and Prevention, said she felt a sense of “impending doom” about a potential new surge in cases. President Biden said states should pause their reopening efforts, warning that the country is “giving up hard-fought, hard-won gains.”

Cases, deaths and hospitalizations remain well below the peak levels seen in January. But infection numbers have started rising again, to about 66,000 a day, fueled mostly by pervasive outbreaks on the East Coast and in the Upper Midwest.

The country is a study in contrasts.

Connecticut, New Jersey, New York and other states in the Northeast continue to report high levels of cases, and troubling upticks have emerged in Illinois, Minnesota and some other Midwestern states. But in much of the South and West, case numbers remain relatively low.

California is reporting continued declines, Arizona is averaging about 550 cases a day, down from more than 10,000. And in Arkansas, fewer than 200 cases are being announced most days, down 40 percent in the last two weeks.

But if any place offers a glimpse at the threat of a new surge, it is Michigan.

More than 2,200 coronavirus patients statewide are hospitalized, a figure that has more than doubled since the beginning of March. On Monday, the health system announced that it would reinstate a policy limiting visitors at several hospitals, in response to the latest surge.  ...

ALSO SEE: Gov. Whitmer is holding off for now on Michigan COVID limits. Here’s why.