Recombivax HB is a recombinant vaccine that protects against the Hepatitis B virus (HBV). It is a non-infectious subunit viral vaccine; it does not contain the live virus, but a purified component. It prevents Hepatitis B, a serious viral infection primarily affecting the liver. Recombivax HB is approved for all ages to prevent this liver disease.
Understanding Hepatitis B and the Vaccine’s Role
Hepatitis B is a viral infection affecting the liver, causing inflammation and damage. It can cause acute (short-term) or chronic (long-term) illness. Transmission occurs through contact with infected bodily fluids like blood, semen, and vaginal fluids. This includes shared needles, unprotected sexual contact, or mother-to-baby transmission during birth.
Chronic Hepatitis B can persist for decades, causing liver damage, cirrhosis (liver scarring), and hepatocellular carcinoma (liver cancer). It is estimated to cause over half of all liver cancers worldwide. The risk of chronic infection is high in infants infected at birth or early childhood; about 90% of infected infants develop chronic infections, compared to 2% to 6% of infected adults.
Recombivax HB introduces the non-infectious Hepatitis B surface antigen (HBsAg) into the body. HBsAg is produced in yeast cells using recombinant DNA technology. The immune system recognizes this HBsAg as foreign and produces anti-HBs antibodies. These antibodies provide active immunity, preparing the body to fight a real Hepatitis B infection. An antibody concentration of 10 mIU/mL or greater is considered protective against HBV.
Who Should Receive the Vaccine and When
Universal Hepatitis B vaccination is recommended, starting at birth. Newborns should receive their first dose to prevent mother-to-child transmission. Infants typically receive a three-dose series at 0, 1, and 6 months. For infants under 2 kg (4.4 lbs) born to HBsAg-negative mothers, vaccination may be delayed until one month of age or hospital discharge.
Children and adolescents not vaccinated in infancy should receive catch-up vaccination. For those up to 19 years, the standard is a three-dose series at 0, 1, and 6 months. Adolescents aged 11-15 years have an alternative two-dose schedule: 1.0 mL at 0 months and the second 1.0 mL dose 4-6 months later.
Adult vaccination is also recommended for various groups at increased risk of HBV infection. This includes healthcare workers and individuals who are exposed to blood or bodily fluids. Other populations for whom vaccination is recommended include individuals with certain medical conditions, such as chronic liver disease or kidney disease, those with multiple sexual partners, people who inject drugs, and household contacts of persons infected with Hepatitis B. Travelers to areas where Hepatitis B is common are also advised to get vaccinated.
For adults 20 years of age and older, the typical schedule involves three 1.0 mL doses given at 0, 1, and 6 months. For adult predialysis and dialysis patients, a 40 mcg (1.0 mL) dose is administered in a three-dose series at 0, 1, and 6 months.
Safety Profile and Administration
Recombivax HB is generally well-tolerated, and common side effects are usually mild and temporary. These frequently include reactions at the injection site, such as pain, soreness, redness, or swelling. Other common, mild systemic reactions that may occur include low-grade fever, headache, fatigue, malaise (a general feeling of being unwell), diarrhea, diminished appetite, irritability, and runny nose. These reactions typically resolve within a few days to weeks.
Serious adverse reactions to Recombivax HB are rare, but severe allergic reactions, such as anaphylaxis, are a possibility. Vaccination sites are prepared to manage such reactions, which can manifest as breathing problems, wheezing, a racing heart, swelling of the face, lips, mouth, tongue, or throat, or low blood pressure leading to dizziness or fainting. Contraindications for Recombivax HB include a history of a severe allergic or hypersensitivity reaction to a previous dose of any Hepatitis B-containing vaccine or to any component of Recombivax HB, including yeast. The vaccine’s vial stopper and syringe plunger stopper may contain dry natural latex rubber, which can cause allergic reactions in individuals sensitive to latex.
Recombivax HB is administered as an intramuscular injection. For adults, adolescents, and children aged one year and older, the preferred injection site is the deltoid muscle in the upper arm. For infants younger than one year, the anterolateral aspect of the thigh is the recommended site for injection. It is important that the vaccine is not administered in the gluteal region, as injections in the buttocks can result in lower rates of protective antibody development.
Subcutaneous administration may be considered for individuals at risk of bleeding following intramuscular injections, such as hemophiliacs, though this method may lead to a lower antibody response. The vaccine should not be given intravenously or intradermally.