Among older subjects given 20 mcg at months 0, 1, and 6, the seroprotection rate 1 month after the third dose was 88%. However, as with other hepatitis B vaccines, in adults over 40 years of age, ENGERIX-B vaccine produced anti-HBs titers that were lower than those in younger adults (GMT among seroconverters 1 month after the third 20-mcg dose with a 0-, 1-, and 6-month schedule: 610 mIU/mL for individuals over 40 years of age, N = 50).
In a clinical trial of subjects with chronic hepatitis C, 31 subjects received ENGERIX-B on the usual 0-, 1-, and 6-month schedule. All subjects responded with seroprotective titers. The GMT of anti-HBs was 1,260 mIU/mL (95% CI: 709-2,237).
Hemodialysis patients given hepatitis B vaccines respond with lower titers,12 which remain at protective levels for shorter durations than in normal subjects. In a study in which patients on chronic hemodialysis (mean time on dialysis was 24 months; N = 562) received 40 mcg of the plasma-derived vaccine at months 0, 1, and 6, approximately 50% of patients achieved antibody titers ≥10 mIU/mL.12 Since a fourth dose of ENGERIX-B given to healthy adults at month 12 following the 0-, 1-, and 2-month schedule resulted in a substantial increase in the GMT (see above), a 4-dose regimen was studied in hemodialysis patients. In a clinical trial of adults who had been on hemodialysis for a mean of 56 months (N = 43), 67% of patients were seroprotected 2 months after the last dose of 40 mcg of ENGERIX-B (2 × 20 mcg) given on a 0-, 1-, 2-, and 6-month schedule; the GMT among seroconverters was 93 mIU/mL.
In 3 comparative clinical trials with 1,339 adults and 587 children, the thimerosal free formulation performed as well as the preservative free formulation that contained trace amounts of thimerosal.
Recombinant DNA vaccines are produced in yeast by expression of a hepatitis B virus gene sequence that codes for the hepatitis B surface antigen. Like plasma-derived vaccine, the yeast-derived vaccines are protein particles visible by electron microscopy and have hepatitis B surface antigen epitopes as determined by monoclonal antibody analyses. Yeast-derived vaccines have been shown by in vitro analyses to induce antibodies (anti-HBs) which are immunologically comparable by epitope specificity and binding affinity to antibodies induced by plasma-derived vaccine.13 In cross-absorption studies, no differences were detected in the spectra of antibodies induced in man to plasma-derived or to yeast-derived hepatitis B vaccines.13
Additionally, patients immunized approximately 3 years previously with plasma– derived vaccine and whose antibody titers were <100 mIU/mL (GMT: 35 mIU/mL; range: 9– 94) were given a 20-mcg dose of ENGERIX-B. All patients, including 2 who had not responded to the plasma-derived vaccine, showed a response to ENGERIX-B (GMT: 5,069 mIU/mL; range: 624– 15,019). There have been no clinical studies in which a 3– dose vaccine series was initiated with a plasma-derived hepatitis B vaccine and completed with ENGERIX-B, or vice versa. However, because the in vitro and in vivo studies described above indicate the comparability of the antibody produced in response to plasma– derived vaccine and ENGERIX-B, it should be possible to interchange the use of ENGERIX-B and plasma-derived vaccines (but see CONTRAINDICATIONS).
A controlled study (N = 48) demonstrated that completion of a course of immunization with 1 dose of ENGERIX-B (20 mcg, month 6) following 2 doses of RECOMBIVAX HB® * (10 mcg, months 0 and 1) produced a similar GMT (4,077 mIU/mL) to immunization with 3 doses of RECOMBIVAX HB (10 mcg, months 0, 1, and 6; 2,654 mIU/mL). Thus, ENGERIX-B can be used to complete a vaccination course initiated with RECOMBIVAX HB.14
In 1 study, 4 of 244 (1.6%) adults (homosexual men) at high risk of contracting hepatitis B virus became infected during the period prior to completion of 3 doses of ENGERIX-B (20 mcg at 0, 1, and 6 months).15 No additional patients became infected during the 18-month follow-up period after completion of the immunization course.
ENGERIX-B is indicated for immunization against infection caused by all known subtypes of hepatitis B virus. As hepatitis D (caused by the delta virus) does not occur in the absence of hepatitis B infection, it can be expected that hepatitis D will also be prevented by ENGERIX-B vaccination.
ENGERIX-B will not prevent hepatitis caused by other agents, such as hepatitis A, C, and E viruses, or other pathogens known to infect the liver.
Immunization is recommended in persons of all ages, especially those who are, or will be, at increased risk of exposure to hepatitis B virus,1 for example:
- Infants, Including Those Born of HBsAg-Positive Mothers (See DOSAGE AND ADMINISTRATION.)
- Adolescents (See CLINICAL PHARMACOLOGY.)
- Healthcare Personnel: Dentists and oral surgeons. Dental, medical, and nursing students. Physicians, surgeons, and podiatrists. Nurses. Paramedical and ambulance personnel and custodial staff who may be exposed to the virus via blood or other patient specimens. Dental hygienists and dental nurses. Laboratory and blood bank personnel handling blood, blood products, and other patient specimens. Hospital cleaning staff who handle waste.
- Selected Patients and Patient Contacts: Patients and staff in hemodialysis units and hematology/oncology units. Patients requiring frequent and/or large volume blood transfusions or clotting factor concentrates (e.g., persons with hemophilia, thalassemia, sickle cell anemia, cirrhosis). Clients (residents) and staff of institutions for the mentally handicapped. Classroom contacts of deinstitutionalized mentally handicapped persons who have persistent hepatitis B surface antigenemia and who show aggressive behavior. Household and other intimate contacts of persons with persistent hepatitis B surface antigenemia.
- Subpopulations With a Known High Incidence of the Disease, such as: Alaskan Eskimos. Pacific Islanders. Indochinese immigrants. Haitian immigrants. Refugees from other HBV-endemic areas. All infants of women born in areas where the infection is highly endemic.
- Individuals With Chronic Hepatitis C: Risk factors for hepatitis C are similar to those for hepatitis B. Consequently, immunization with hepatitis B vaccine is recommended for individuals with chronic hepatitis C.
- Persons Who May Be Exposed to the Hepatitis B Virus by Travel to High-Risk Areas (See ACIP Guidelines, 1990.)
- Military Personnel Identified as Being at Increased Risk
- Morticians and Embalmers
- Persons at Increased Risk of the Disease Due to Their Sexual Practices,1,16 such as: Persons with more than 1 sexual partner in a 6-month period. Persons who have contracted a sexually transmitted disease. Homosexually active males. Female prostitutes.
- Users of Illicit Injectable Drugs
- Others: Police and fire department personnel who render first aid or medical assistance, and any others who, through their work or personal life-style, may be exposed to the hepatitis B virus. Adoptees from countries of high HBV endemicity.
The ACIP states that, in general, simultaneous administration of certain live and inactivated pediatric vaccines has not resulted in impaired antibody responses or increased rates of adverse reactions.17 Separate sites and syringes should be used for simultaneous administration of injectable vaccines.
Hypersensitivity to any component of the vaccine, including yeast, is a contraindication (see DESCRIPTION). This vaccine is contraindicated in patients with previous hypersensitivity to any hepatitis B-containing vaccine.
The vial stopper is latex-free. The tip cap and the rubber plunger of the needleless prefilled syringes contain dry natural latex rubber that may cause allergic reactions in latex sensitive individuals.
Hepatitis B has a long incubation period. Hepatitis B vaccination may not prevent hepatitis B infection in individuals who had an unrecognized hepatitis B infection at the time of vaccine administration. Additionally, it may not prevent infection in individuals who do not achieve protective antibody titers.
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