The hepatitis A virus (HAV) is primarily transmitted by the fecal-oral route, either by person-to-person contact or consumption of contaminated food or water. It has an incubation period of about 28 days (range: 15–50 days). Among adults the infection is typically symptomatic with fever, fatigue, loss of appetite, nausea, vomiting, abdominal pain, dark urine, clay-colored bowel movements, joint pain, and jaundice. HAV infection is self-limiting and does not result in chronic liver disease.51
Active Immunization: Hepatitis A Vaccine 4,6,52
There are two inactivated hepatitis A whole-virus vaccines (Vaqta, Havrix) and a combination hepatitis A and B vaccine (Twinrix) available (Table 10). Twinrix contains the same hepatitis A component as Havrix, but half the dose. Hepatitis A vaccination is recommended for adults who are at high risk for Hepatitis A including individuals with specific health conditions such as chronic liver disease and HIV. In addition, it is recommended for anyone at an increased risk of Hepatitis A such as those who use illicit drugs, men who have sex with men, international travelers, close personal contact to an international adoptee, experiencing homelessness, and those at risk of healthcare-associated exposure. Vaccination with Vaqta and Havrix consists of 2 doses; vaccination with Twinrix requires 3 doses.
Table 10. Hepatitis A Vaccines52
| Vaccines | Indications | Schedules | Adverse Effects |
|---|
Vaqta
Havrix | Pre- and post-exposure | 2 IM doses at 0 and 6-18 months 2 IM doses at 0 and 6-12 months | Erythema, edema, pain at injection site; malaise, fever, and fatigue may occur. |
| Twinrix | Preexposure | 3 IM doses at 0, 1, and 6 months | As above plus anaphylaxis in persons with history of allergic reaction to baker’s yeast. |
Passive Immunization: Immune Globulin
Immune globulin is available for short-term pre- and post-exposure protection (approximately 3 months) against hepatitis A. Immune globulin must be administered within 2 weeks after exposure for maximum protection.6
