Call Uber for a ride home and now for a flu shot, too? The car service announced Thursday a one-day UberHEALTH pilot program in partnership with Harvard Medical School's Vaccine Finder program to deliver free flu shots on demand. During the promotion, Uber drivers transported a registered nurse to deliver and inject the shot to customers anywhere within the three test cities of New York, Boston and Washington.

An insurance card was not required to participate. Users were asked to arrange a meeting location with the nurse. "We know the flu is preventable, and we know our riders are always on the go," the car service said. "We expect demand for UberHEALTH to be high, so your patience is appreciated."

Harvard professor John Brownstein, whose group came up with the idea, said it has "huge potential" to "deliver more convenience into delivery of care." For every shot doled out, Uber pledged to donate $5 to the Red Cross to support vaccination efforts for children, including its Measles & Rubella Initiative.

It's unclear if the service worked. “I tried to summon the Flüber a handful of times, starting at 10 a.m. sharp. No dice,” Galen Moore writes for BostInno. “Just for fun, I moved the pin over to Boston’s Longwood Medical Area, arguably the tightest concentration of advanced health care institutions in the world. Still nothing.”

Uber is known for its aggressive marketing tactics. Founded in 2009, the ride-sharing service exists in 45 countries and has raised at least $1.5 billion in venture capital. Marketed as “everyone’s private driver,” the app lets anyone request a car using a GPS location and a credit card. In September, co-founder Travis Kalanick claimed the company creates 50,000 new jobs around the world every month.