The most effective way to prevent hepatitis B virus (HBV) infection is the hepatitis B vaccine. A comprehensive strategy to eliminate HBV includes universal vaccination of infants at birth; routine screening of all pregnant women for hepatitis B surface antigen (HBsAg); postexposure immunoprophylaxis of infants born to women who test positive for HBsAg or women with unknown HBsAg status; and vaccination of adults at risk of HBV infection who were not previously vaccinated.

Ongoing HBV transmission occurs in unvaccinated adults who have risk behaviors for HBV transmission (e.g., those who use injection drugs, men who have sex with men). The prevalence of HBV infection also is high among sex partners and other close contacts of persons with chronic HBV infection.

Clinical Features

HBV predominantly replicates in the liver, and the infection can be asymptomatic or symptomatic. Infants, children younger than five years, and immunosuppressed adults with newly acquired HBV infection usually are asymptomatic. However, when symptoms are present, they can include malaise, nausea, anorexia, abdominal pain, jaundice, and vomiting. Skin rashes, arthritis, arthralgias, and other extrahepatic manifestations also can occur.

The mortality rate for persons with acute hepatitis B is 0.5 to 1.0 percent, with the highest rates occurring in persons older than 60 years. However, the overall fatality rate is likely lower because many infections are asymptomatic and are not reported. Specific treatment for acute hepatitis B does not exist, and the mainstay of therapy is supportive care. Therapeutic agents approved by the U.S. Food and Drug Administration can sustain suppression of HBV replication and remission of liver disease in certain persons with chronic hepatitis B.

Epidemiology

Serum, semen, and saliva have been shown to be infectious, with serum containing the highest concentration of HBV. [ corrected] The two primary sources of HBV infection in adults are percutaneous exposure to blood and sexual contact. HBV transmission also can occur in settings that involve nonsexual interpersonal contact over an extended period.

Sexual contact among men who have sex with men and among heterosexual couples can transmit HBV. Unprotected intercourse with more than one partner, a history of another sexually transmitted disease, and having unprotected intercourse with a person infected with HBV are risk factors for sexual transmission. Receipt of a blood transfusion or organ or tissue transplant from a donor infected with HBV, use of injection drugs, and frequent exposure to blood or needles are risk factors for percutaneous transmission of HBV.

Household contacts of persons who are chronically infected are at risk of HBV infection through percutaneous or mucosal exposure, and persons with chronic HBV infection can transmit the virus in other settings (e.g., child care centers, schools).

Vaccine Administration

Physicians should administer the hepatitis B vaccine to adults by injection into the deltoid muscle. Intradermal administration is not recommended because it may result in a lower seroconversion rate and a lower final concentration of anti-HBsAg. Physicians should revaccinate patients who did not receive their vaccine intramuscularly at the recommended site, unless serologic testing indicates that an adequate response has been achieved. Patients who received inadequate doses of the vaccine and those who were vaccinated after a dosing interval shorter than recommended should be revaccinated using the correct schedule or dosage.

If other vaccinations are given to the patient during the same office visit, they should be given at different injection sites. For patients at risk of hemorrhage (e.g., patients with hemophilia), physicians should use a 23-gauge or smaller needle and apply direct pressure to the injection site for one to two minutes and administer the vaccine after infusion of a coagulation factor. Subcutaneous administration may be considered for these patients, but it could result in an increased local reaction and a lower serologic response.

Adults who are unvaccinated and who are at risk of HBV infection should be vaccinated, as should adults who are not at high risk but request the vaccine (Table 1). Physicians should develop appropriate strategies to ensure that adult patients at risk of HBV infection also are offered the vaccine.

Any adverse events should be reported to the Vaccine Adverse Events Reporting System by calling (800) 822-7967 or visiting http://www.vaers.hhs.gov.

Assessing the needs of adult patients for other vaccines is recommended, and these vaccinations should be administered at the same time as the hepatitis B vaccine. Health care professionals should vaccinate all persons in contact with those who have HBsAg, and they should provide counseling and medical management referrals to these patients.

Patient education about the importance of hepatitis B vaccination should be given to all adults at risk of HBV infection. Additionally, the vaccine should be offered in a way that is convenient, flexible, and accessible to all patients.

HIGH-RISK HEALTH CARE SETTINGS

If a patient has not completed a licensed hepatitis B vaccine series and presents in a health care setting where there is a high percentage of patients at risk of HBV infection, he or she should be assumed also to be at risk of HBV infection (Table 2) and should be offered the vaccine.

Physicians should routinely administer the vaccine to adults who have not completed the vaccine series, and the vaccine should be a standard component of the evaluation and treatment of sexually transmitted diseases, including human immunodeficiency virus and acquired immunodeficiency syndrome. If possible, physicians should offer the hepatitis B vaccine in outreach and other settings that provide health care to patients at risk of HBV infection.

OCCUPATIONAL HEALTH CARE SETTINGS

Health care professionals and other staff (e.g, paramedics, attending physicians, employees, students, volunteers) who are exposed to potentially infectious bodily fluids in a health care, public safety, laboratory, or institutional setting should be provided education to encourage hepatitis B vaccination. They should also be provided with reminders to track completion of the vaccination series and postvaccination testing.