The approach to Vatican Correspondent Nicole Winfield came from a member of a task force that had investigated care at Italy’s foremost pediatric facility, known as “the pope’s hospital.” The contact feared that serious concerns raised by the task force hadn’t been addressed two years later.

That tip, in late 2015, set the AP on a 20-month investigation of the Bambino Gesu (Baby Jesus) Pediatric Hospital. Winfield teamed up with London-based Medical Writer Maria Cheng to reveal a dark chapter in the facility's history. They found that children sometimes paid the price as administrators tried to make the money-losing enterprise turn a profit, and Vatican officials took pains to keep the concerns quiet.

Their work earns the Beat of the Week.

Among the investigation’s findings:

— Overcrowding and poor hygiene contributed to deadly infection, including one 21-month superbug outbreak in the cancer ward that killed eight children.

— To save money, disposable equipment and other materials were at times used improperly, with a one-time order of cheap needles breaking when injected into tiny veins.

— Doctors were so pressured to maximize operating-room turnover that patients were sometimes brought out of anesthesia too quickly.

In Rome, Winfield interviewed current and past hospital staff, some through her own contacts and others provided by the task force member, an American nurse named Coleen McMahon. Winfield also dug through medical records, civil court rulings, hospital and Vatican emails and five years of union complaints, and interviewed lawyers, patients and families who had won lawsuits against the hospital. She even flew to Las Vegas one weekend to speak with McMahon on camera.

Cheng also flew to Rome. She dug into the medical side of the story, gauging the seriousness of the findings by sounding out experts in anesthesiology, oncology, virology, medical ethics and other specialties. She interviewed some of the world’s top doctors, and her research into journals discovered the superbug outbreak that had not before been reported outside medical publications.

When Winfield asked the hospital for comment at the end of 2016, the hospital issued a detailed denial, threatened legal action and revealed the existence of a second report, by Sister Carol Keehan, an American Catholic health care expert.

That’s when another aspect of the story became clear: Instead of informing Italian health authorities who pay the hospital’s bills about the numerous problems discovered by the task force, the Vatican commissioned a second investigation that spent three days at the hospital and concluded that everything was fine.

Hospital officials initially called the AP story a hoax and threatened legal action.

When the AP story moved July 3, hospital officials called the report a hoax and again threatened legal action. A day later, however, Vatican officials conceded that there had been problems and that the hospital was working to fix them.

The multi-format package was featured in newspapers across the world. NewsWhip showed 140 uses for the main bar, 135 for the Latest and 42 for the abridged. The Tuesday follow-up story saw 138 hits, and 117 for the Latest. Engagement for the main bar averaged 1.42 minutes, peaking at times above 4 minutes. (The next-most-engaged stories that day were a couple of pieces on President Trump at about 45 seconds). The video, produced by Jo Mateus in London, received 44 hits on 13 channels in Teletrax.

For their tenacious reporting into shortcomings at the Vatican’s showcase children’s hospital, Winfield and Cheng share this week’s $500 Beat of the Week prize.