Denver public health officials say four homeless people have been diagnosed with hepatitis A this year, so the city is stepping up free vaccinations.

KDVR-TV reports that three of the cases were diagnosed within the past three weeks.

Denver Public Health executive director Dr. Bill Burman says his agency will set up vaccine clinics almost every day in day shelters, syringe access programs, Civic Center Park and other places where people at risk of contracting the disease are found.

Hepatitis A can be spread through sharing of drugs and equipment, fecal-oral contamination or intimate contact with a person who has the disease.

Health officials say the disease can be prevented with a vaccine that’s been a part of standard childhood immunizations for more than a decade.