Top 5 Takeaways

  1. Significant Shift in Hepatitis A Epidemiology: The U.S. has experienced extensive hepatitis A outbreaks from 2016 to 2020, primarily due to person-to-person transmission rather than contaminated food.
  2. High-Risk Populations: The majority of the cases were associated with drug use (56%), homelessness (14%), and a significant portion with hospitalizations (61%) and deaths (380).
  3. Demographic Data: Predominantly affecting males (62%), White individuals (81%), and the age group 30–49 years.
  4. Critical Role of Vaccination: Emphasis on increased hepatitis A vaccination, especially among high-risk groups, is crucial for outbreak control and future prevention.
  5. Ongoing Public Health Efforts: Substantial progress has been made, with 24 states declaring their outbreaks over by September 2022, due to intensive vaccination and outreach strategies.

Original Article Author and Citation

Corresponding Author

Megan G. Hofmeister,, 404-718-5458.

Suggested Citation

Foster MA, Hofmeister MG, Yin S, et al. Widespread Hepatitis A Outbreaks Associated with Person-to-Person Transmission — United States, 2016–2020. MMWR Morb Mortal Wkly Rep 2022;71:1229–1234. DOI:


This article documents widespread hepatitis A outbreaks in the United States from 2016-2020, marking a notable shift in the epidemiology of the disease. Unlike previous outbreaks linked to contaminated food, these were attributed to person-to-person transmission. Approximately 37,553 cases were reported across 33 states during this period, with significant implications for public health practice.


The Centers for Disease Control and Prevention (CDC) analyzed data from 33 of the 36 outbreak-affected states, representing about 97% of reported cases. The study focused on demographic profiles, risk factors, and clinical outcomes of the cases. Data collection was conducted using state-specific case investigation forms and analysis was performed using SAS.


This outbreak represented a significant shift in the transmission and demographics of hepatitis A cases in the U.S., shifting from children and minority groups to predominantly adult White males involved in drug use or experiencing homelessness. The increase in hospitalizations and deaths highlighted the severity of these outbreaks. The study emphasized the critical role of targeted vaccination strategies, especially for high-risk groups, in controlling and preventing future outbreaks.


The report concludes that improved hepatitis A vaccination coverage, along with targeted strategies for at-risk populations, is vital for responding to current outbreaks and preventing similar future occurrences. The lessons learned from these outbreaks are relevant for improving public health responses to vaccine-preventable diseases in marginalized groups.


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