The vast majority of the prisoners at the Guantanamo Bay detention center have reportedly received the first dose of the vaccine against the Chinese coronavirus after the U.S. military began offering it early this week.

Of the 40 detainees held at the U.S. military prison, 32 had received the first dose of the two-shot Moderna vaccine as of Tuesday, U.S. Southern Command said, without explaining why the eight remaining men had not received the drug, the Associated Press (AP) reported Tuesday.

U.S. Southern Command, or SOUTHCOM, oversees the American military base in Guantanamo, Cuba.

There is no requirement to inoculate the detainees at the prison, commonly known as Gitmo.

It is unclear if Khalid Sheikh Mohammed (KSM), the mastermind behind the Sept. 11, 2011 attacks, and his four co-conspirators are among the vaccinated prisoners. They are still awaiting trial nearly two decades after they executed the attacks, the deadliest on American soil.

On Monday, the U.S. military resumed the effort to inoculate the detainees, initiated during the last days of the Trump administration, after the Pentagon halted it in response to outcry from the public, including victims of the attacks, and lawmakers, particularly Republicans.

At the time of the criticism, the vaccines were just being rolled out to troops and civilians at the U.S. naval base in Guantanamo and were not widely available to the public in the U.S.

The move to begin vaccinating the prisoners coincided with President Joe Biden’s deadline for states to start inoculating all Americans older than 16 and all adults at the U.S. military base in Cuba.

Citing an official who spoke on condition of anonymity, the New York Times reported Monday that the Biden administration’s decision to vaccinate the prisoners aims in part to protect the undisclosed number of service members at the facility who had declined the inoculation.

“This is very much about the force protection of our people down there and the ability to move forward with the military commissions,” the official told the Times, adding, “We have a legal obligation under international law to properly vaccinate these detainees.”

Citing an unnamed senior defense official, the Associated Press (AP) added Monday:

The defense official said all 40 men held at the Navy base in Cuba will be offered the vaccination to comply with legal requirements regarding the treatment of prisoners and to help prevent COVID-19 [coronavirus disease] from spreading. Strict quarantine procedures had already sharply curtailed activities at the base and halted legal proceedings for prisoners facing war crime trials, including the men charged in the Sept. 11, 2001, attack.

“Obviously, we don’t want an outbreak of COVID [coronavirus disease] on a remote island with the challenges that would present,” the official told AP ahead of an official announcement.

The Pentagon reportedly notified Congress hours before making the vaccine available to the detainees Monday.

That day, the New York Times noted:

A memo dated Dec. 23 described the detainees as “a high-risk community,” and invoked both “the Geneva Convention and Department of Defense guidance.”

But the Pentagon postponed plans to start the vaccinations on Feb. 1, after elected officials and victims of the attacks accused the Defense Department of putting terrorism suspects ahead of the American people, who were only just starting to get access to the vaccines in substantial numbers at that point.

By Monday, the official said, all of the adults at the remote base in Cuba had been offered a vaccine, including the troops and civilian Defense Department employees — 1,500 in all — who work at the detention operation. An undisclosed number of staff members at the prison had declined.

There are about 5,500 residents at the U.S. military base in Guantanamo, including 250 school-aged children and a foreign labor force of nearly 2,200 Jamaican and Filipino workers contracted by the Pentagon.

“As of April 1, according to health officials at the base, all but about 400 adults were entitled to vaccines, and about 47 percent of those eligible had not taken a single dose,” the Times reported.

It is reportedly unclear how many people have caught the virus at the base, separated from the rest of Cuba by a minefield.

After acknowledging two cases early during the pandemic, both involving service members who recovered, the military reportedly censored specific disclosures.

There have been no known coronavirus cases among the 1,500 Pentagon employees that run the prison or any of the detainees.