BEVERLY — Barbara Clay walked into CVS yesterday to talk to the pharmacist and walked out with a flu shot.

"How convenient," she said.

CVS is hoping more customers like Clay will stumble across their new walk-in health clinics that opened yesterday in Beverly and Danvers.

The clinics, known as MinuteClinics, are staffed by nurse practitioners who treat common illnesses such as strep throat and ear infections. CVS is branding them as a time-saving, convenient alternative to making an appointment with your doctor when it comes to less serious medical problems.

"We've done lots of studies, and our average wait time is 15 minutes," said Richard Arnold, the manager of the clinics in Beverly and Danvers.

At the CVS in the North Beverly plaza, the clinic consists of two examination rooms near the pharmacy. Patients sign in at a touch-screen kiosk while the prices for various treatments scroll across a computer screen.

Arnold said the nurse practitioners treat only common illnesses and would refer any patient with more serious symptoms, such as chest pains, to a hospital. But some doctors worry about the gap that could develop with their primary care physician if a patient relies on a walk-in clinic for treatment.

"There's a lack of connection to the person's medical home, their primary care office, where somebody keeps files on their allergies and medications," said Dr. Nathan Kaufman of Marblehead. "They could put somebody on medication, and it doesn't end up on our list."

Kaufman said there could also be a problem if a patient does not know the exact kind of medication they are taking. If they give the wrong prescription name at the walk-in clinic, the nurse practitioner could administer a common antibiotic that does not interact well with the medication, he said.

Arnold said MinuteClinics are not trying to take the place of doctors.

"We encourage people to use their primary care," he said. "We refer patients to their primary care. We also tell them, 'Feel free if you're swamped to refer them to us.'"

Arnold said treatments at the clinics are covered by most major insurance companies. Patients who don't have insurance would pay about the same as they would at a doctor's office, he said. The clinics are open seven days per week, and no appointment is needed.

CVS has opened more than 540 MinuteClinics across the country since 2000 but have only recently come to Massachusetts. The Beverly and Danvers clinics are the fifth and sixth in the state.

Clay, an 82-year-old Beverly resident, said she didn't know about the clinic until she walked into the CVS in North Beverly yesterday.

She asked Arnold how much it would cost her for a flu shot. When he said her insurance would cover the full cost, she decided to get the shot.

"I think it's wonderful," she said. "It's one of the best ideas they've ever had."