Doctors and nurses often suggest that patients get an annual flu shot. But do they roll up their own sleeves?

At a handful of area hospitals, the answer is often no. In the most recent data compiled by the federal government, 13 facilities in Pennsylvania, New Jersey, and Delaware reported that fewer than 60 percent of health-care workers had received a flu vaccination.

Among them were four in the Philadelphia area, including the three hospitals in the Inspira Health Network in South Jersey: Inspira Medical Center Elmer (at 35 percent, tied with a hospital in North Jersey for the lowest flu-shot rate in the three states), Inspira Medical Center Vineland (45 percent), and Inspira Medical Center Woodbury (57 percent).

But since the end of the six-month period represented in the data — Oct. 1, 2016, through March 31, 2017 — the network has started requiring flu shots for all employees, both in hospitals and outpatient settings, said Paul Lambrecht, vice president for quality and patient safety.

Frequent hand-washing, another recommended preventive measure, requires constant effort. But flu shots are a commonsense way to reduce the risk of infection without day-to-day action, he said.

"It's protection you don't even have to think about," Lambrecht said. "You get your vaccination, and you go about your life. You're protecting yourself and others."

The fourth Philadelphia-area facility with a flu vaccination rate below 60 percent was Barix Clinics of Pennsylvania, a bariatric surgery center in Langhorne, at 38 percent. A Barix spokesperson did not respond to a request for comment.

The highest vaccination rate in Pennsylvania, New Jersey, and Delaware was 99 percent, a figure reported by these area hospitals:

Bucks County. Doylestown Hospital, Grand View Hospital, Jefferson Bucks Hospital (formerly Aria), and Rothman Orthopaedic Specialty Hospital.

Montgomery County. Abington Hospital-Jefferson Health, Lansdale Hospital, and Holy Redeemer Hospital.

Philadelphia. Jefferson Frankford Hospital, Jefferson Torresdale Hospital (both formerly Aria Health), and Roxborough Memorial Hospital.

The three former Aria hospitals started requiring flu vaccines in the 2011-12 season, said Kelli Wiercinski, director of infection prevention and employee health. Most employees get the shot during special "blitz days." For others who may be unable to leave their work station, such as emergency-room physicians, the hospitals administer flu shots from mobile carts, she said.

The vaccination-rate figures are compiled by the Centers for Medicare and Medicaid Services on its Hospital Compare web site, at medicare.gov/hospitalcompare.

The evidence is mixed as to whether vaccinating doctors, nurses, and other health-care workers reduces the number of patients that get sick, but the prevailing wisdom is that the shots are a good idea. The U.S. Centers for Disease Control and Prevention recommends that all health-care workers get an annual flu shot, both to protect patients and employees.

Some hospitals encourage vaccination, while others, like Inspira, have instituted outright requirements. At hospitals with vaccination mandates, there has been occasional resistance among employees who have no contact with patients. Others may object for religious reasons or because they are allergic to an ingredient in the vaccine.

Concocting the annual flu vaccine requires educated guesswork, so getting a shot does not guarantee you won't get flu.  But the CDC says recent reports that it is only 10 percent effective this year are wrong — as that figure refers to just one strain, and is based on Australia's experience. Overall effectiveness is more likely closer to last year's, 39 percent.

And the vaccine is the best option medicine offers to reduce the risk of contracting the illness. Even in those who do get sick, having had the vaccine can reduce the severity of symptoms. Most patients recover after a week of misery, but flu viruses are blamed in thousands of deaths each year.

As in any workplace, doctors and nurses who get the flu are advised to stay home, but some of them nevertheless decide to drag themselves in to work. In a recent CDC survey, four in 10 health-care professionals said they came to work while suffering flu-like symptoms.