CRITICAL MEDICINE

HEPATITIS B VACCINE ADMINISTRATION

Definition

The hepatitis B vaccine is a recombinant vaccine that provides active immunity against the hepatitis B virus (HBV). It is highly effective in preventing hepatitis B infection, chronic liver disease, cirrhosis, and hepatocellular carcinoma.

Route of Administration

• Intramuscular (IM) injection is the recommended route.
• Do not administer by the intravenous route.
• Subcutaneous administration is reserved only for patients with severe bleeding disorders when IM injection is contraindicated.

Site of Injection

Infants (Birth to 12 Months)

• Anterolateral aspect of the mid-thigh (vastus lateralis muscle).

Children (1–2 Years)

• Anterolateral thigh or deltoid muscle (if adequately developed).

Children (>2 Years), Adolescents, and Adults

• Deltoid muscle of the upper arm is the preferred site.

Avoid

• Gluteal region because vaccine response may be reduced due to injection into fat tissue.

Dose

• Infants and children: 0.5 mL IM
• Adolescents and adults: 1.0 mL IM
• Dose may vary slightly depending on the vaccine manufacturer.

Standard Vaccination Schedule

Infants

• Birth dose: Within 24 hours of birth.
• Second dose: 1–2 months
• Third dose: 6–18 months

Adults

• Three-dose schedule: 0, 1, and 6 months.

Accelerated Schedule (When Rapid Protection is Needed)

• 0, 1, 2 months, followed by a booster at 12 months.

Post-Exposure Prophylaxis

For exposure to hepatitis B virus:

• Administer Hepatitis B vaccine as soon as possible.
• Add Hepatitis B Immunoglobulin (HBIG) when indicated (e.g., newborns of HBsAg-positive mothers or significant occupational exposure).

Contraindications

• Previous severe allergic reaction (anaphylaxis) to a hepatitis B vaccine dose or vaccine component.
• Severe acute illness (vaccination should be deferred until recovery).

Common Adverse Effects

• Pain, redness, or swelling at the injection site.
• Mild fever.
• Fatigue.
• Headache.
• Serious allergic reactions are extremely rare.

Storage

• Store at 2°C–8°C.
• Do not freeze.
• Protect from excessive heat and direct sunlight.

Effectiveness

• Protective antibody levels develop in more than 90–95% of healthy individuals after completing the vaccination series.
• Immunity is long-lasting, and routine booster doses are not recommended for immunocompetent individuals after a complete primary series.

Key Points

• Administer intramuscularly in the deltoid muscle (adults) or anterolateral thigh (infants).
• Give the birth dose within 24 hours of delivery.
• Follow the recommended vaccination schedule for maximum protection.
• Avoid the gluteal region for routine administration.
• Maintain the cold chain at 2°C–8°C to preserve vaccine potency.

HOW TO MANAGE  IF THE BOOSTER DOSE IS MISSED AND WHAT TO DO

Missed Hepatitis B Vaccine Dose – What to Do

A missed hepatitis B vaccine dose does not require restarting the vaccination series, regardless of how much time has elapsed. Simply administer the missed dose as soon as possible and complete the remaining doses according to the recommended schedule.

If the Second Dose Is Missed

• Give the second dose immediately when the person presents.
• Administer the third dose at least 8 weeks after the second dose and at least 16 weeks after the first dose.
• Do not restart the series.

If the Third (Booster/Final Primary) Dose Is Missed

• Give the third dose immediately, even if months or years have passed.
• The vaccine series is then considered complete.
• There is no need to repeat the first or second doses.

If Many Years Have Passed

• Resume the vaccination schedule from where it stopped.
• Previous doses remain valid.
• There is no maximum interval between doses that requires restarting the series.

After Exposure to Hepatitis B

If an incompletely vaccinated person is exposed to hepatitis B (e.g., needle-stick injury, sexual exposure, or contact with HBsAg-positive blood):

• Administer the next due hepatitis B vaccine dose immediately.
• Hepatitis B Immunoglobulin (HBIG) may also be required depending on:
• Vaccination status
• Anti-HBs antibody level (if known)
• Source patient's HBsAg status

Is a Routine Booster Dose Needed?

For immunocompetent individuals:

• Routine booster doses are not recommended after a complete primary vaccination series because immune memory persists even if antibody levels decline.

Booster doses may be indicated for selected high-risk groups, such as:

• Patients on hemodialysis
• Some immunocompromised individuals (e.g., advanced HIV infection, transplant recipients)
• People with documented loss of protective antibody levels when ongoing risk is present

These groups should undergo periodic anti-HBs testing, and a booster is recommended if the anti-HBs level falls below 10 mIU/mL.

Key Rule

Never restart the hepatitis B vaccine series because of a missed dose. Continue from the point where vaccination was interrupted and complete the remaining dose(s) as soon as possible. This recommendation is supported by major immunization guidelines, including those of the World Health Organization and the Centers for Disease Control and Prevention.

                                                      DR.C.GANESAN M.D.,

                                                 PROFESSOR OF MEDICINE