As thousands of Jews in Nazi-occupied Italy were being sent to concentration camps in the fall of 1943, a group of dissident doctors figured out a way to save dozens of lives: Fabricate a disease so contagious and so deadly that Nazi soldiers would be too scared to even be in the same room as anyone infected by it.

Though their actions wouldn't be revealed until 60 years later, the ruse began on October 16, 1943, when Nazis raided a Jewish ghetto near Rome's Tiber River. As Jews were being rounded up, the doctors hid a number of runaways inside the walls of the nearby Fatebenefratelli Hospital. It was then that the doctors, including Vittorio Sacerdoti and a surgeon named Giovanni Borromeo, came up with a plan to diagnose the refugees with a fictitious disease. They called it Syndrome K.

To pull it off just right, the Nazis had to believe these patients had a lethal disease that could infect anyone who came into contact with them. In the cramped quarters of deportation trains, one sick passenger could infect everyone on board—soldiers included.

The name Syndrome K came from Dr. Adriano Ossicini, an anti-Fascist physician working at the hospital who knew they needed a way for the staff to differentiate which people were actually patients and which were Jews in hiding. Inventing a fake disease cut out all the confusion—when a doctor came in with a "Syndrome K" patient, everyone working there knew which steps to take. “Syndrome K was put on patient papers to indicate that the sick person wasn’t sick at all, but Jewish,” Ossicini told Italian newspaper La Stampa in 2016. “We created those papers for Jewish people as if they were ordinary patients, and in the moment when we had to say what disease they suffered? It was Syndrome K, meaning ‘I am admitting a Jew,’ as if he or she were ill, but they were all healthy ... The idea to call it Syndrome K, like Kesselring or Kappler, was mine.”

The "Kesselring" Ossicini was referring to was Albert Kesselring, the Nazi commander who, among other things, was in charge of Hitler's Italian occupation; meanwhile, Herbert Kappler was the SS chief responsible for a mass reprisal killing in 1944. Naming a deadly contagion after two ruthless Nazi commanders must have felt fitting for Ossicini and the other doctors at the hospital.

Syndrome K wasn't just a pet name to distinguish actual patients from Jews in hiding; the doctors had to find ways to make the disease seem real when Nazi troops combed the hospital for people to round up. To do so, the doctors would have special rooms filled with "victims" of Syndrome K (also called "K" Syndrome), which they warned the soldiers was a highly contagious, disfiguring, and deadly disease.

The Nazi troops, scared of contracting the mysterious ailment, wouldn't even bother to inspect the people in the rooms when they raided the hospital. There were also children to worry about, so the doctors coached them on how to cough violently enough to ward off any inspections that a curious soldier may want to conduct.

"[The] Nazis thought it was cancer or tuberculosis, and they fled like rabbits," Dr. Sacerdoti told the BBC in 2004. Syndrome K hit close to home for Sacerdoti, who used the disease to save his 10-year-old cousin, Luciana Sacerdoti.

When, more than a half-century later, the doctors' fabrication was finally revealed, they became recognized for their life-saving actions. Borromeo was recognized as “Righteous Among the Nations" by Yad Vashem, a World Holocaust Remembrance Center. He was also integral in orchestrating the transfer of many Jewish patients from hospitals in the ghettos to Fatebenefratelli in order to get them better treatment in a safer environment before the raids began.

The hospital itself was even recognized as a "House of Life" by the International Raoul Wallenberg Foundation, which advocates on behalf of Holocaust saviors. In the years leading up to the raids, the hospital had become known as a haven for persecuted Jews. The hospital administration at the time, including Borromeo, allowed doctors like Sacerdoti—a Jew who had been fired from previous jobs because of his religion—to work under false documents.

The actual number of people saved by the doctors at Fatebenefratelli was probably around a couple dozen. No matter the final tally, though, the quick thinking and ingenuity of doctors like Sacerdoti, Borromeo, and Ossicini were a glimmer of hope during a time when happy endings were in short supply.