Hepatitis is the main manifestation of viral infection in humans is caused by only five virus species: hepatitis A virus (HAV), hepatitis B virus (HBV), hepatitis C virus (HCV), hepatitis D virus (HDV), and hepatitis E virus (HEV). All of the hepatitis viruses cause acute hepatitis; HBV frequently causes chronic hepatitis. Chronic hepatitis can lead to cirrhosis which may progress to hepatocellular carcinoma (HCC), the most common type of primary liver cancer.Infection with HBV may occur perinatally (vertical transmission-mother to child), during early childhood (the so-called horizontal spread-. child to child), through sexual contact, or nosocomially.
The World Health Organization (WHO) has recommended universal hepatitis B vaccination.
The currently available vaccine containing the surface antigen of hepatitis B is produced by recombinant technology in yeast and adjuvanted with aluminum salts and preserved with thimerosal (thimerosal-free vaccines are also available) since 1986. Hepatitis B vaccine is available as single- and multidose vials and should be stored at 2–8°C. The vaccine should not be frozen; frozen vaccine should be discarded.Hepatitis B vaccines are available as monovalent formulations for birth doses or for vaccination of older persons at risk, and in combination with other vaccines for infant vaccination, including diphtheria- tetanus-pertussis (DTP), Haemophilus influenzae type b (Hib), and inactivated polio vaccine (IPV).Interchange of brands is permitted but not routinely recommended
Immunogenicity, Efficacy and Effectiveness
The protective efficacy of hepatitis B vaccination is related to the induction of antibody to hepatitis B surface antigen (anti-HBs) antibodies, but also involves the induction of memory T-cells. An anti-HBs concentration of 10 mIU/mL measured 1–3 months after administration of the last dose of the primary vaccination series is considered a reliable correlate of protection against infection.The primary three-dose vaccine series induces protective antibody concentrations in >95% of healthy infants, children, and young adults.
Dosage and Administration
The dose in children and adolescents (aged less than 18 years) is 0.5 mL/10 μg and in those 18 years and older is 1 mL/20 μg. It should be injected intramuscularly in the deltoid/anterolateral thigh.Injections should be avoided due to low gluteal immunogenicity. The vaccine is extremely safe and well tolerated.
The primary three-dose hepatitis B vaccination series for monovalent vaccines, consists of one monovalent birth dose followed by either two doses of monovalent or hepatitis B-containing combination vaccine administered during the same visits as the first and third doses of DTP-containing vaccines. Alternatively, four doses of hepatitis B vaccine may be given for programmatic reasons (e.g. one monovalent birth dose followed by three monovalent or hepatitis B-containing combination vaccine doses) administered during the same visits as the three doses of DTP-containing vaccines.The additional dose is not harmful. Delay in administration of the birth dose to infants of chronically infected mothers increases the risk of perinatal HBV transmission.The classical schedule is 0, 1, and 6 months. The vaccine is highly immunogenic and seroconversion rates are greater than 90% after a three-dose schedule.
Seroconversion rates are lower in the elderly, the immunocompromised, and those with chronic renal failure (might require a booster after checking antibody titres) . Four doses at 0,1, 2, and 12 months of double dose may be given in these patients.Routine testing for anti-HBsAg levels 1 month after completion of the immunization schedule is recommended in children born to HBsAg positive mothers, health care workers, and those with comorbidities. Antibody titers greater than 10 mIU/mL signify a response and are considered protective.Nonresponders should be tested for hepatitis B carrier status. If found to be negative, the same three-dose schedule should be repeated. Almost all respond to a three-dose revaccination schedule.
Although the 0-1-6 schedule is the preferred schedule, hepatitis B vaccine schedules are very flexible and there are multiple options for adding the vaccine to existing national immunization schedules without requiring additional visits for immunization. These include:
- Birth, 6, and 14 weeks
- 6, 10, and 14 weeks
- Birth, 6 weeks, 6 months
- Birth, 6 weeks, 10 weeks, 14 weeks.
The birth dose can reduce perinatal transmission by 18–40%.Delay in the administration of the first dose beyond the 7th day of life has been shown to be associated with higher rates of HBsAg acquisition in later childhood.
None of the above schedules needs a booster.
Routine boosters are not needed in healthy children and adults. Studies have shown that individuals who had responded to the vaccination series and had levels of 10 mIU/mL after vaccination are protected against hepatitis B disease for life even if the levels drop to below protective levels or are undetectable later. This is due to immune memory. In the immunocompromised and those with comorbidities such as chronic renal disease, levels should be checked periodically and booster vaccination given whenever levels drop to below protective levels.
Hepatitis B vaccines do not interfere with the immune response to any other vaccine and vice versa. The immune responses and safety of hepatitis B-containing combination vaccines are comparable to those observed when the vaccines are administered separately.
HEPATITIS B IMMUNOGLOBULIN
Hepatitis B immunoglobulin (HBIg) provides passive immunity and is indicated along with hepatitis B vaccine in management of perinatal/occupational/sexual exposures to hepatitis B in susceptible individuals.5 The dose of HBIg in adults is 0.06 mL/kg and in neonates/infants 0.5 mL. HBIg should be stored at 2–8°C and should not be frozen. HBIg provides temporary protection lasting 3–6 months. HBIg should never be given intravenously. HBIg is also used alone following exposure to hepatitis B in patients who are nonresponders to hepatitis B vaccination (genetic reasons/ immunocompromised status). In this situation, two doses of HBIg 1 month apart are indicated.
Management of an Infant Born to Hepatitis B Positive Mother
If the mother is known to be HBsAg negative, hepatitis B vaccine can be given in the 0–6 weeks–6 months schedule.
If the mother is HBsAg positive (and especially HBeAg positive), the baby should be given HBIg along with hepatitis B vaccine within 12 hours of birth, using two separate syringes and separate sites for injection. The dose of HBIg is 0.5 mL intramuscular. HBIg may be given up to 7 days of birth but the efficacy of HBIg after 48 hours is not known.
IMMUNIZATION OF PRETERM INFANTS
Preterm infants and low-birth weight infants with birth weight less than 2,000 grams have a decreased response to hepatitis B vaccines administered before the age of 1 month. However, by the chronological age of 1 month, preterm babies irrespective of their initial birth weight and gestational age are likely to respond as adequately as full-term infants.
Recommendations for Preterm Infants
• Greater than 2,000 g: As for full-term infants.
• Less than 2,000 g:
- – Mother HBsAg negative: Dose 1 at 30 days of age, dose 2 and 3
as per schedule adopted for full-term infants.
- – Mother HBsAg positive: Hepatitis B vaccine + HBIg (within 12 hours of birth), continue vaccine series with three more doses beginning at 4–6 weeks of age as per schedule for full-term infants. Immunize with four doses, do not count birth dose as part of vaccine series.8 Check anti-HBs and HBsAg 1 month after completion of vaccine series.