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Response to Hepatitis A Vaccine in Children after a Single Dose with a Booster Administration 6 Months Later
Findor1, Cañero Velasco MC, Mutti
1Professor, Universidad de Buenos Aires, División de Gastroenterología, Hospital de Clínicas "Jose de San Martin," Buenos Aires, Argentina.
Insights
A single dose plus a booster of inactivated hepatitis A vaccine (HAV) at 0 and 6 months is safe and effective for children. This vaccination schedule induces a robust immune response, providing excellent protection against hepatitis A infection.
Area of Science:
- Pediatrics
- Immunology
- Vaccinology
Background:
- Children are a vulnerable population for hepatitis A virus (HAV) infection.
- Pediatric hepatitis A vaccination began in 1993 with a two-dose regimen.
- The need for a simplified pediatric vaccination schedule prompted this study.
Purpose of the Study:
- To evaluate the immunogenicity and safety of a two-dose inactivated hepatitis A vaccine schedule in children.
- To assess the feasibility of a primary dose followed by a booster at 6 months.
Main Methods:
- Sixty healthy, seronegative children aged 2-13 years received an inactivated HAV vaccine (720 ELISA units) at 0 and 6 months.
- Antibodies against HAV (anti-HAV) were measured using ELISA inhibition assay (seropositive ≥20 mIU/mL).
- Symptom diaries were used to record adverse events post-vaccination.
Main Results:
- 96% seropositivity was achieved 15 days post-primary dose, reaching 100% by 1 month.
- 93% maintained seropositivity before the booster dose at 6 months.
- 100% seropositivity and a significant GMT increase (3644 mIU/mL) were observed 1 month after the booster.
Conclusions:
- The inactivated hepatitis A vaccine is safe and well-tolerated in children.
- A single dose plus a 6-month booster schedule is highly immunogenic.
- This regimen provides excellent protection against hepatitis A in pediatric populations.
Abstract:
Background: Children are of an age group susceptible to infection by the hepatitis A virus (HAV). Active immunization of children against HAV became reality in 1993, when the first pediatric hepatitis A vaccine was licensed. This initial vaccine required two injections to induce a full immune response in recipients. The purpose of this study was to assess the feasibility of a single dose primary vaccine plus a booster after 6 months against hepatitis A in children. Methods: A total of 60 healthy and seronegative children between 2 and 13 years of age were administered inactivated hepatitis A vaccine, containing 720 enzyme-linked immunosorbent assay (ELISA) units (EL.U) of hepatitis A antigen, intramuscularly in the deltoid region at months 0 and 6. Symptoms were recorded by parents or guardians on individual diary cards. Antibodies against HAV (antiHAV) were measured using an ELISA inhibition assay, and a seropositive titer was defined as being >=20 mIU/mL. Results: Fifteen days after the single primary dose, 96% of the vaccinees were seropositive with a geometric mean titer (GMT) of 351 mIU/mL. The seropositivity rate reached 100% 1 month after the first dose, with a GMT of 305 mIU/mL. Prior to the second dose at month 6, 93% remained seropositive, and the GMT was 153 mIU/mL. By month 7, 1 month after the second vaccination, the seropositivity rate recovered to 100% with a rise in GMTs to 3644 mIU/mL. Local symptoms were reported after 23.9% of doses, and general symptoms after 19.7% of doses. All symptoms were of short duration and resolved spontaneously. Conclusions: This inactivated vaccine against hepatitis A is safe, well-tolerated, and excellently immunogenic when administered to children following a single dose plus booster course at months 0 and 6.