WASHINGTON (AP) — The Bureau of Prisons has started vaccinating staff members and some inmates at the federal prison complex where the Justice Department carries out federal executions, as officials work to contain a coronavirus outbreak at the facility.

Doses of the coronavirus vaccine had been delivered to 19 prisons, including the Federal Correctional Complex in Terre Haute, Indiana, by Wednesday, a Bureau of Prisons spokesman told The Associated Press. They include some prisons that have been hit the hardest during the pandemic.

Nearly 7,100 federal inmates and more than 1,600 Bureau of Prisons staff members across the country had active, positive test results for COVID-19 on Wednesday, including 406 inmates at the federal penitentiary in Terre Haute. Since March, 179 federal inmates across the country have died after contracting the virus.

The agency has struggled for months to combat the exploding number of coronavirus cases in federal prisons across the U.S. Federal statistics show there are currently more inmates with positive COVID-19 test results at the Terre Haute penitentiary than at any other federal prison in the country. The number of cases at the prison has increased exponentially in recent weeks; when the last execution was carried out earlier this month, 133 inmates at the facility had the virus.

Two men who are scheduled to be executed by the federal government next month, Cory Johnson and Dustin John Higgs, are among the inmates at Terre Haute who have tested positive for the virus. The Justice Department said in a court filing this week that both had been “medically cleared from isolation” but were still exhibiting symptoms of the virus.

Attorneys for both of the men have asked federal courts to step in and halt the executions. The government has opposed those requests. Another execution, for Lisa Montgomery, the only woman on federal death row, had been scheduled for the same week, but a federal judge vacated an order from the director of the Bureau of Prisons, saying the Justice Department had unlawfully rescheduled the execution after Montgomery’s attorneys contracted coronavirus visiting their client and asked him to extend the amount of time to file a clemency petition.

The Bureau of Prisons had initially planned to reserve doses of the coronavirus vaccine only for its staff members, but said last week that some high-risk inmates had also been vaccinated. But so far, the agency has not said how many inmates have been vaccinated or how it selects those to receive the vaccine.

A spokesman for the bureau said roughly half of the staff at each of the facilities has received the vaccine and that remaining doses “were, and will be, provided to inmates based on priority of need,” in accordance with guidelines from the Centers for Disease Control and Prevention.

Additional doses will be given to other inmates when they become available, the agency said.