Iowa has tossed out tens of thousands of expired COVID-19 vaccine doses and could toss out hundreds of thousands more if demand for the vaccine continues to lag in the state, health officials there said.

Iowa Department of Public Health spokeswoman Sarah Ekstrand said Monday that the state has tossed more than 81,000 doses of the vaccine, the Des Moines Register reported.

“It’s so sad that we’re throwing away so many doses when we know the vaccine works,” said Rachel Reimer, chair of the Department of Public Health at Des Moines University, adding that millions of people in other countries are desperate to get the vaccine. “And we literally cannot give it away.”

Federal officials have said states can’t return unused vaccines to the manufacturers or donate them to other states or countries, Ekstrand said.

“We have exhausted all options prior to vaccine expiring,” she told the Register in an email.

The department warned last month that the state might have to discard around 217,000 doses by the end of August unless demand rose.

Health officials said they’ve seen a bump in demand for the vaccine recently, as cases have surged over the summer. But demand is still far below what it was in April, when the shots first became available.

The federal Centers for Disease Control and Prevention reported Monday that 59% of eligible Iowa residents had been fully vaccinated. In some counties, fewer than 40% of residents have been vaccinated.