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. The heavy concentration of new cases in states that account for 22 percent 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 …