Most hepatitis A infections in recent years have been linked to drug use or homelessness, according to research published by the Centers for Disease Control and Prevention (CDC) Morbidity and Mortality Weekly Report.

“These outbreaks mark a shift in hepatitis A epidemiology in the United States,” CDC researchers reported.

Until now, travel and food contamination were the primary modes of hepatitis A transmission.

The research found that from 2016 to 2020, 56% of people with hepatitis A used drugs, 14% were experiencing homelessness and 12% had been recently incarcerated. From 2000 to 2015, only 3.5% of cases were associated with drug use, most of which were reported in the Latino population.

"Before the introduction of hepatitis A vaccines…transmission was driven largely by spread from asymptomatically infected children, and hepatitis A disproportionately affected racial and ethnic minority populations,” the researchers wrote.

Between 2016 to 2020, there were 44,650 cases of hepatitis A, 27,250 hospitalizations and 415 deaths. Most cases occurred in white men ages 30 to 49. In contrast, there were 1,398 cases reported in 2011 and 1,390 in 2015.

The researchers emphasize that hepatitis A can be prevented through vaccination.

“Increased hepatitis A vaccination coverage, particularly through implementation of successful, nontraditional vaccination strategies among disproportionately affected populations, is needed to continue progress in halting current outbreaks and preventing similar outbreaks in the future,” the authors wrote.