Nearly half of new coronavirus infections nationwide are in 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% 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.

The heavy concentration of new cases in states that account for 22% of the U.S. population has prompted some experts and elected officials to call for President Joe Biden’s administration to ship additional vaccine doses to those places. So far, the White House has shown no signs of shifting from its policy of dividing vaccine doses among states based on population.

Sending extra doses to places where infection numbers are climbing makes sense, said Dr. Elvin H. Geng, a professor in infectious diseases at Washington University. But it’s also complicated. States that are more successfully controlling the virus might see less vaccine as a result.

“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.”

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. Only New York reported higher case numbers. And California and Texas, which have vastly larger populations than Michigan, are reporting less than half its number of daily infections.

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 York City, vaccination appointments are still challenging to get. Mayor Bill de Blasio has publicly harangued the federal government about the need for a bigger vaccine allotment almost daily, a refrain he repeated when speaking to reporters Tuesday.

“We still need supply, supply, supply,” de Blasio said, before adding, “But things are really getting better.”

On the state level, Gov. Andrew Cuomo has not called publicly for an increase in New York’s vaccine allotment, even as cases ticked up in recent weeks and the number of hospitalized people hit a plateau.

In New Jersey, where the seven-day rolling average of daily new infections has risen during 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% 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.

New virus variants are clearly one of the drivers in the increase, said Dr. Kirsten Bibbins-Domingo, chair of the department of epidemiology and biostatistics at the University of California, San Francisco. Failure to suppress the rise in cases will lead to more people getting sick and dying, she said, and drive increases in other parts of the country.

“More vaccine needs to be where the virus is,” Bibbins-Domingo said, adding that people should get over the “scarcity mindset” that has them thinking surging vaccine into one place will hurt people elsewhere.

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 the most serious 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’ “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.”