DES MOINES — Nearly half of Iowa’s counties have rejected new doses of COVID-19 vaccine because of a lack of demand, state officials said Tuesday amid a public information campaign meant to drum up interest in immunization.

Forty-three of Iowa’s 99 counties declined additional shipments of the vaccines, the state reported. Of the 43 counties, the U.S. Centers for Disease Control and Prevention has identified 12 as having a high rates of coronavirus transmission: Clay, Clayton, Dickinson, Emmet, Fremont, Ida, Lyon, O’Brien, Palo Alto, Sac, Taylor and Woodbury. Voter registration information shows that all 12 are heavily Republican counties, which have shown to be more resistant to vaccine acceptance.

A poll by The Associated Press-NORC Center for Public Affairs Research in late March found that 36 percent of Republicans said they will probably or definitely not get vaccinated, compared with 12 percent of Democrats. Similarly, a third of rural Americans said they were leaning toward not getting shots, while fewer than a fourth of people living in cities and suburbs shared that hesitancy.

Clay County in northwestern Iowa, for example, has nearly 28 percent of the population fully vaccinated, which slightly trails Iowa’s statewide rate of 28.7 percent. But a gap between Clay’s rate and the statewide figure will likely grow if vaccination numbers stall, and the county already has a positivity rate that is among the highest in Iowa at 168.58 per 100,000 people.

During the seven-day period that ended Monday, Iowa had the nation’s 32nd highest daily infection rate, at 97.2 cases per 100,000 people.

The state Department of Public Health has advised its county counterparts to decline doses when they can’t ensure their ability to use them all, said spokeswoman Sarah Ekstrand.

“These counties are doing exactly what we have asked of them,” she said.

The counties still receive a weekly allocation, but they can accept it or decline a portion as their needs fluctuate.

Ekstrand said the state health department is working with counties “to determine where additional education and public awareness campaigns are needed to gain an understanding of the needs of each county’s unique population.”

The state, Iowa State University and the University of Iowa have hosted live, virtual information sessions on COVID-19 vaccination during which experts answered questions about vaccine creation, safety and effectiveness.