Nearly half of new coronavirus infections nationwide are in just five states – a situation that is putting pressure on the federal government to consider changing how it distributes vaccines by sending more doses to hot spots.

New York, Michigan, Florida, Pennsylvania and New Jersey together reported 44 percent of the nation’s new COVID-19 infections, or nearly 197,500 new cases, in the latest available seven-day period, according to state health agency data compiled by Johns Hopkins University. Total U.S. infections during the same week numbered more than 452,000.

Surging vaccines to places where the number is going up makes sense, said Dr. Elvin H. Geng, a professor in infectious diseases at Washington University. But it’s also complicated.

“You wouldn’t want to make those folks wait because they were doing better,” Geng said. “On the other hand, it only makes sense to send vaccines to where the cases are rising.”

So far, President Joe Biden’s administration has shown no signs of shifting from its policy of dividing vaccine doses among states based on population.

The spike in cases has been especially pronounced in Michigan, where the seven-day average of daily new infections reached 6,719 cases Sunday – more than double what it was two weeks earlier.

Though Michigan has seen the highest rate of new infections in the past two weeks, Democratic Gov. Gretchen Whitmer has said she does not plan to tighten restrictions. She has blamed the virus surge on pandemic fatigue, which has people moving about more, as well as more contagious variants.

Whitmer got her first vaccine shot Tuesday, the day after Michigan expanded eligibility to everyone 16 and older. She asked the White House last week during a conference call with governors whether it has considered sending extra vaccine to states battling virus surges. She was told all options were on the table.

In New Jersey, where the seven-day rolling average of daily new infections has risen over the past two weeks from 4,050 daily cases to 4,250, Democratic Gov. Phil Murphy said he is constantly talking to the White House about demand for the coronavirus vaccine, though he stopped short of saying he was lobbying for more vaccines because of the state’s high infection rate.

Vaccine shipments to New Jersey are up 12 percent in the last week, Murphy said Monday, though he questioned whether that’s enough.

“We constantly look at, OK, we know we’re going up, but are we going up at the rate we should be, particularly given the amount of cases we have?” Murphy said.

Former Food and Drug Administration Commissioner Scott Gottlieb has urged the Biden administration to push additional coronavirus shots into parts of the U.S. experiencing outbreaks including Michigan, New York and New Jersey.

“I think what we need to do is try to continue to vaccinate, surge vaccine into those parts of the country,” Gottlieb said in a March 28 appearance on CBS’s “Face the Nation.” “So the incremental vaccine that’s coming onto the market, I think the Biden administration can allocate to parts of the country that look hot right now.”

Researcher Joshua Schwab of the University of California at Berkeley recently estimated that doubling the current vaccine allocation in Michigan for two weeks could reduce hospitalization admissions by 10,000 and deaths by 1,200 by July. He concluded that far greater reductions could be achieved if extra vaccines were combined with some restrictions being put back in place.

Talk of sending extra shots to states struggling with outbreaks comes at a time when the number of daily infections in the U.S. has fallen dramatically compared to a January spike following the holiday season. However, the seven-day average of daily infections been rising slowly since mid-March.

The five states seeing the most infections stand out. California and Texas, which have vastly larger populations than Michigan, are reporting less than half its number of daily infections. And as of Tuesday, 31 U.S. states were reporting seven-day averages of fewer than 1,000 new daily cases.

White House coronavirus coordinator Jeff Zients said Tuesday more than 28 million doses of COVID-19 vaccines will be delivered to states this week. That allocation will bring the U.S. total to more than 90 million doses distributed in the past three weeks.

The news came as Biden announced more than 150 million coronavirus shots in arms have been administered since he took office, and that all adults will be eligible to receive a vaccine by April 19.

About 40 percent of U.S. adults have now received at least one COVID-19 shot, according to the Centers for Disease Control and Prevention. Only 23 percent of American adults have been fully vaccinated — including more than half of Americans 65 and older.

Geng said the nation should take a step back and go slow. Even just a few more weeks of Americans sticking with social distancing and other precautions could make a huge difference.

“The take-home message here is, let’s not jump the gun,” Geng said. “There’s light at the end of the tunnel. We all see it there. And we will get there. Slow and steady.”

Bynum reported from Savannah, Georgia. Smith reported from Providence, Rhode Island. Associated Press writers Darlene Superville in Washington, David Eggert in Lansing, Michigan, and Michael Catalini in Trenton, New Jersey, also contributed to this report.