Remember that the current recommendation is to vaccinate all children 12 to 23 months old with HepA, in 2 separate doses. Two single-antigen HepA products are available: Havrix (GSK) and Vaqta (Merck). For the 2-dose sequence, Havrix is given at 0 and 6 to 12 months; Vaqta at 0 and 6 to 18 months. Even a single dose will provide protection for up to 11 years. In addition to these vaccines, there is the combination HepA and HepB vaccine (Twinrix) mentioned earlier.
Previous recommendations for preventing hepatitis A after exposure, made in 2007, stated that HepA vaccine was preferred for healthy individuals ages 12 months through 40 years, while immune globulin (IG) was preferred for adults older than 40, infants before their first birthday, immunocompromised individuals, those with chronic liver disease, and those for whom HepA vaccine is contraindicated.8 The 2007 recommendations also advised vaccinating individuals traveling to countries with intermediate to high hepatitis A endemicity.
A single dose of HepA vaccine was recommended for all those 12 months or older, although older adults, immunocompromised individuals, and those with chronic liver disease or other chronic medical conditions planning to visit an endemic area in ≤ 2 weeks were supposed to receive the initial dose of vaccine and could also receive IG (0.02 mL/kg) if their provider advised it. Travelers who declined vaccination, those younger than 12 months, or those allergic to a vaccine component could receive a single dose of IG (0.02 mL/kg), which provides protection up to 3 months.
Several factors influenced ACIP to reconsider both the pre- and post-exposure recommendations. Regarding IG, evidence of its decreased potency over time led the committee to increase the recommended dose (see below). IG also must be re-administered every 2 months, the supply of the product is questionable, and many health care facilities do not stock it. By comparison, HepA vaccine offers the advantages of easier administration, inducing active immunity, and providing longer protection. Another issue involved infants ages 6 to 11 months traveling to an area with endemic measles transmission and who must therefore receive the measles, mumps, and rubella (MMR) vaccine. MMR and IG should not be co-administered, and, for infants, the health risk from measles outweighs that from hepatitis A.
Updated recommendations. After considering all this information, ACIP made the following changes to its hepatitis A virus (HAV) prevention recommendations (in addition to adding homeless people to the list of HepA vaccine recipients)9:
- Administer HepA vaccine as post-exposure prophylaxis to all individuals 12 months and older.
- IG may be administered, in addition to HepA vaccine, to those older than 40 years, depending on the provider’s risk assessment (degree of exposure and medical conditions that might lead to severe complications from HAV infection). The recommended IG dose is now 0.1 mL/kg for post-exposure prevention; it is 0.1 to 0.2 mL/kg for pre-exposure prophylaxis for travelers, depending on the length of planned travel.
- Administer HepA vaccine alone to infants ages 6 to 11 months traveling outside the United States when protection against hepatitis A is recommended.
These recommendations have been published in the Morbidity and Mortality Weekly Report.9