Hepatitis A Viral Infection

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.31

Active Immunization: Hepatitis A Vaccine4,6

There are two inactivated hepatitis A whole-virus vaccines (Vaqta, Havrix) and a combination hepatitis A and B vaccine (Twinrix) available (Table 9). Twinrix contains the same hepatitis A component as Havrix, but half the dose. Hepatitis A vaccination is recommended for adults with chronic liver disease, illicit drug users, and those at risk of healthcare-associated exposure. Vaccination with Vaqta and Havrix consists of 2 doses; vaccination with Twinrix requires 3 doses.

Table 9. Hepatitis A vaccines.4,6
Vaccines Indications Schedules Adverse Effects

Pre- and post-exposure2 IM doses 6 months apartErythema, edema, pain at injection site; malaise, fever, and fatigue may occur.
TwinrixPreexposure3 IM doses at 0, 1, and 6 monthsAs 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.