Widespread Hepatitis A Outbreaks Associated with Person-to-Person Transmission - United States, 2016-2020.

Hepatitis A is a vaccine-preventable disease typically acquired through fecal-oral transmission. Hepatitis A virus (HAV) infection rates in the United States declined approximately 97% during 1995-2015 after the introduction and widespread pediatric use of hepatitis A vaccines (1). Since 2016, hepatitis A outbreaks have been reported in 37 states, involving approximately 44,650 cases, 27,250 hospitalizations, and 415 deaths as of September 23, 2022 (2). A report describing early outbreaks in four states during 2017 noted that most infections occurred among persons reporting injection or noninjection drug use or experiencing homelessness; this finding signaled a shift in HAV infection epidemiology from point-source outbreaks associated with contaminated food to large community outbreaks associated with person-to-person transmission (3). CDC analyzed interim data from 33 outbreak-affected states to characterize demographic, risk factor, and clinical outcome data from 37,553 outbreak-associated hepatitis A cases reported during August 1, 2016-December 31, 2020. Among persons with available risk factor or clinical outcome information, 56% reported drug use, 14% reported experiencing homelessness, and 61% had been hospitalized; 380 outbreak-associated deaths were reported. The most effective means to prevent and control hepatitis A outbreaks is through hepatitis A vaccination, particularly for persons at increased risk for HAV infection (4). The epidemiologic shifts identified during these outbreaks led to a 2019 recommendation by the Advisory Committee on Immunization Practices (ACIP) for vaccination of persons experiencing homelessness and reinforcement of existing vaccination recommendations for persons who use drugs (4). Substantial progress in the prevention and control of hepatitis A has been made; the number of outbreak-affected states has been reduced from 37 to 13 (2). Increased hepatitis A vaccination coverage, particularly through implementation of successful, nontraditional vaccination strategies among disproportionately affected populations (5), is needed to continue progress in halting current outbreaks and preventing similar outbreaks in the future.