This patient should receive hepatitis A virus (HAV) vaccine and a dose of intramuscular immune globulin now. Travel-related risk for acquiring HAV depends on the person's immune status to HAV and level of endemicity of this hepatotropic pathogen in the geographic area being visited. The adoption of routine childhood HAV vaccination programs in recent years has greatly decreased the incidence of infection. However, only approximately 40% of adults are immune to HAV and, therefore, are at risk for infection, particularly when traveling to developing parts of South Asia, Africa, and South and Central America. Transmission occurs by the fecal-oral route from close contact with an infected person or ingestion of contaminated water or food. Therefore, active immunization using either of the two available inactivated vaccines is effective for preventing infection and is strongly recommended when traveling to areas of high disease prevalence, such as Cambodia.

One dose of vaccine administered any time before departure generally provides protection to most persons 40 years or younger, although a second dose given 6 to 12 months after the initial dose is required for long-term protection. However, persons older than 40 years, those with chronic medical conditions, immunocompromised persons, or those with chronic liver disease who plan to depart within 2 weeks to an endemic area should be treated with hepatitis A vaccination and intramuscular immune globulin given at a distant injection site to provide optimal protection. The use of immunosuppressive medications (as in this patient), including tumor necrosis factor α inhibitors, is not a contraindication to immunization with killed or inactivated vaccines.

Hepatitis A vaccine is the primary method for triggering immunity to the virus, with immune globulin providing additional protection in patients at high risk. The use of immune globulin alone without hepatitis A vaccination is not indicated or recommended.

Administering hepatitis A vaccine or immune globulin following exposure to hepatitis A in nonimmunized patients (postexposure prophylaxis) is effective in reducing attack rates of infection. However, preexposure prophylaxis is not contraindicated in this patient, and postexposure prophylaxis should not be necessary.