Hepatitis A outbreaks were first identified in 2016 and the hepatitis A virus (HAV) has since then been responsible for more than 15,000 infections, 57% of hospitalizations, and 140 deaths in the United States. HAV is highly transmissible from person-to-person, although outbreaks primarily affect people who use drugs (injection or non-injection); who are homeless; men who have sex with men; people who are, or were recently, incarcerated; and people with chronic liver disease, including cirrhosis, hepatitis B, and hepatitis C. These populations are usually comprised of a number of adults who are unvaccinated for hepatitis A infection. One dose of single-antigen hepatitis vaccine has been shown to provide up to 95% seroprotection in healthy individuals for up to 11 years. Further, pre-vaccination serologic testing is not required in order to administer the hepatitis A vaccine.

An update to the Health Alert Network (HAN) advisory released in June 2018 titled “Outbreak of HAV Infections Among Persons Who Use Drugs and Persons Experiencing Homelessness” recommended that public health departments, healthcare facilities, and partners and programs providing services to affected populations vaccinate at-risk groups against hepatitis A, following the updated recommendations of the Advisory Committee on Immunization Practices (ACIP). The ACIP recommended that individuals 12 months and older and people who are homeless receive a hepatitis A vaccination for post-exposure prophylaxis. In people older than 40 years who are immunocompromised or have chronic liver disease, providers can also administer immunoglobulin.

For health departments, new recommendations have been made regarding outreach, case investigation, contact tracing, outbreak response monitoring, and outbreak prevention. For outreach, health departments should focus on identifying venues serving populations at-risk for HAV infection and promote education and vaccination efforts, employ novel approaches to improve vaccine delivery in hard-to-reach populations to increase vaccination coverage, and engage multidisciplinary stakeholders (including disease experts, health educators, epidemiologists, etc.) to help make effective response efforts more successful.

Further, health departments should implement the new 2019 Acute Hepatitis A Case Definition from the Council of State and Territorial Epidemiologists, follow established procedures for interviewing cases and performing contact tracing for all new hepatitis A diagnoses, provide and encourage post-exposure prophylaxis of previously unvaccinated contacts within 2 weeks of exposure, and track vaccine delivery and administration in at-risk populations in order to monitor the outbreak response efforts and improve vaccine coverage in at-risk populations. To prevent outbreaks, health departments are encouraged to continue to proactively develop and implement prevention strategies and rapidly mobilize these responses a soon as a case of hepatitis A is identified.

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Healthcare providers should screen patients for risk factors; recommend and administer hepatitis A vaccine in at-risk patients, especially in the emergency department; record immunizations in the state immunization information system; consider hepatitis A as a diagnosis in any person who presents with jaundice or clinically compatible symptoms; and report all individuals diagnosed with hepatitis A to the health department to ensure timely case investigation and follow-up of contacts.

Overall, increasing surveillance, outreach, and vaccination in at-risk populations will hopefully lead to more control and prevention of Hepatitis A outbreaks and transmission.

Reference

Centers for Disease Control and Prevention. Update: Widespread Outbreaks of Hepatitis A among People Who Use Drugs and People Experiencing Homelessness across the United States. https://emergency.cdc.gov/han/HAN00418.asp. Accessed March 28, 2019.