Recommendations on hepatitis A vaccination were recently updated by the Advisory Committee on Immunization Practices (ACIP) and published on Nov. 2 in the CDC's Morbidity and Mortality Weekly Report (MMWR).
Based on a systematic review by the ACIP Hepatitis Work Group, two recommendations were proposed and then unanimously approved by the ACIP:
- Hepatitis A vaccine should be administered for postexposure prophylaxis for all persons ages 12 months and older; in addition to the hepatitis A vaccine, immune globulin may be administered to persons older than 40 years of age for postexposure prophylaxis, depending on the treating clinician's risk assessment.
- Hepatitis A vaccine should be administered to infants ages 6 to 11 months traveling outside the United States when protection against hepatitis A is recommended.
Previously, the recommendations for postexposure prophylaxis in adults older than age 40 years had favored immune globulin, based on the premise that it was more efficacious than the vaccine in this age group. However, recent evidence of decreased potency of immune globulin (i.e., reduced titers of anti-hepatitis A virus antibodies) had led to an increase in the recommended dosage (0.1 mL/kg) for postexposure prophylaxis in 2017, the recommendations noted.
The change in recommendations for traveling infants is due to the concern that immune globulin cannot be administered simultaneously with the measles, mumps, and rubella vaccine because it could inhibit the immune response to the latter for up to three months. The recommendations for pre-exposure protection for travelers of all other ages remain unchanged from previous recommendations, except for some updated dosages of immune globulin.
A report on recent outbreaks of hepatitis A was also published in the Nov. 2 MMWR. During 2017, the CDC received a total of 1,521 reports of acute hepatitis A virus infections from California, Kentucky, Michigan, and Utah. The majority of cases were associated with injection or noninjection drug use or homelessness, and local and state investigations found indications of direct person-to-person transmission. This signals a shift in the epidemiology, as past recent outbreaks were attributed to contaminated food, the report said.
The outbreak was also associated with increased rates of hospitalization and death: 71% of patients were hospitalized and 3% died, compared to 42% and 0.7%, respectively, across the U.S. in 2016. “Increasing vaccination coverage among all at-risk groups recommended by ACIP to receive hepatitis A vaccine might halt ongoing outbreaks and prevent future large community outbreaks,” the report noted.