As of last week, 12 states have reported more than 7,500 hepatitis A infections since January 2017, according to data presented at a meeting of the Advisory Committee on Immunization Practices. There were more than 4,300 hospitalizations and 74 deaths. Homeless people made up more than 40 percent of the cases in San Diego and more than 10 percent of cases in Kentucky, Michigan, Tennessee and West Virginia.

The recommendation would make it easier for shelters, emergency rooms and clinics that serve the homeless to offer hepatitis A shots along with other services. The vaccinations are already recommended as part of universal childhood vaccinations since 2006 and for other at-risk groups, including some international travelers, drug users and men who have sex with men.

The committee of health experts voted unanimously to add homeless people to that list. The panel is responsible for developing recommendations for the Centers for Disease Control and Prevention on the use of vaccines in the United States.

The CDC is expected to adopt the recommendation and send guidance to health-care providers.

The recommendation is for a two-dose series of shots, but even one shot can provide immunity for up to 11 years and possibly even lifetime immunity, said Noele Nelson, who heads the CDC’s team on viral hepatitis.

Nelson estimated the cost of routine vaccination at $16 million to $33 million, but vaccination during a prolonged and rapidly spreading outbreak can be even more expensive and challenging to the health-care system. In San Diego alone, the cost of its outbreak, which was officially declared over last week, was $12.5 million, she said.

Some committee members and other health experts raised concerns about ways to keep track of people who have been vaccinated. They also noted the difficulties in providing routine vaccination to homeless people who do not have access to regular health services or may not remember they had been vaccinated.

Nathaniel Smith, director of the Arkansas Health Department, said the move is welcome. For states that do not have ongoing hepatitis A outbreaks, such a recommendation would allow health-care providers to act to prevent future outbreaks. Immunizations recommended by the expert panel also make it easier for insurance coverage, he said. Some homeless people may be covered under Medicaid, the government health insurance program for low-income people.

The nation’s homeless population increased last year for the first time since 2010, spurred by a surge in the number of people living on the streets in Los Angeles and other West Coast cities, according to a report by the Department of Housing and Urban Development. The report showed nearly 554,000 homeless people nationwide during local surveys conducted in January 2017. That figure was up nearly 1 percent from 2016.

The hepatitis A virus can cause a mild to severe illness lasting a few weeks to several months. In rare cases, it can cause liver failure and death, more commonly in people age 50 and older and in people with other liver diseases. Symptoms include fatigue, fever, loss of appetite and nausea.