More and more people in the United States are flocking to retail medical clinics that aim to emulate fast food restaurants in offering convenience and low prices for a limited menu of the most common medical services.

The clinics are most often set up inside large retail stores such as Walmart or in pharmacies, though some are stand alone operations. Nurses often provide all the services, while some have a supervising doctor who is available for telephone consultations.

The clinics offer treatment for common problems such as sinus and ear infections or small wounds, administer vaccinations, and draw blood for laboratory tests. They refer patients to doctors’ clinics and hospital emergency departments as necessary.

There were about 150 such clinics in …