In this March 16 photo, pharmacist Michael Witte holds a tray with a syringe containing a shot that will be used in the first clinical trial of a potential vaccine for COVID-19 at the Kaiser Permanente Washington Health Research Institute in Seattle. (AP photo)

NEW YORK — Health care workers and nursing home residents should be at the front of the line when the first coronavirus vaccine shots become available, an influential government advisory panel said Tuesday.

The panel voted 13-1 to recommend those groups get priority in the first days of any coming vaccination program, when doses are expected to be very limited. The two groups encompass about 24 million people out of a U.S. population of about 330 million.

Later this month, the Food and Drug Administration will consider authorizing emergency use of two vaccines made by Pfizer and Moderna. Current estimates project that no more than 20 million doses of each vaccine will be available by the end of 2020. And each product requires two doses. As a result, the shots will be rationed in the early stages.

The Advisory Committee on Immunization Practices will meet again at some point to decide who should be next in line. Among the possibilities: teachers, police, firefighters and workers in other essential fields such as food production and transportation; the elderly; and people with underlying medical conditions.

Tuesday’s action merely designated who should get shots first if a safe and effective vaccine becomes available. The panel did not endorse any particular vaccine. Panel members are waiting to hear FDA’s evaluation and to see more safety and efficacy data before endorsing any particular product.

Experts say the vaccine will probably not become widely available in the U.S. until the spring.

The panel of outside scientific experts, created in 1964, makes recommendations to the director of the Centers for Disease Control and Prevention, who almost always approves them. It normally has 15 voting members, but one seat is vacant.

The recommendations are not binding, but for decades they have been widely heeded by doctors, and they have determined the scope and funding of U.S. vaccination programs.

It will be up to state authorities whether to follow the guidance. It will also be left to them to make further, more detailed decisions if necessary — for example, whether to put emergency room doctors and nurses ahead of other health care workers if vaccine supplies are low.

The outbreak in the U.S. has killed nearly 270,000 people and caused more than 13.5 million confirmed infections, with deaths, hospitalizations and cases rocketing in recent weeks.

As the virtual meeting got underway, panel member Dr. Beth Bell of the University of Washington noted that on average, one person is dying of COVID-19 per minute in the U.S. right now, “so I guess we are acting none too soon.”