"Massachusetts, New Jersey, New York, Oregon and Rhode Island are among states that have opened or are planning soon to open sites designed to administer hundreds or even thousands of shots a day," Xinhua news agency quoted The Wall Street Journal as saying on Saturday.
Officials said they are expanding capacity again largely to provide booster shots and reach children who recently have become eligible for vaccines.
Many states shifted to smaller, more-targeted inoculation efforts after demand waned last summer.
Of Americans 5 years or older who are eligible to be vaccinated, 66.3 per cent are fully vaccinated, according to the Centers for Disease Control and Prevention (CDC).
About 38 per cent of fully vaccinated adults have received booster shots.
"Officials running the mass vaccination sites say they also hope to reach some of the 27 per cent of adults who aren't fully vaccinated... Interest among unvaccinated adults hasn't risen during the Omicron surge, though," said The Wall Street Journal report.