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Hepatitis A vaccine: ready for prime time
1Division of Maternal-Fetal Medicine, University of Florida, College of Medicine, Gainesville 32610-0294, USA.
Insights
Two new inactivated hepatitis A vaccines offer long-term protection for individuals over two years old. Recommended for pre-exposure prophylaxis, these vaccines demonstrate high seroconversion rates in clinical trials.
Area of Science:
- Hepatology
- Vaccinology
- Public Health
Background:
- Hepatitis A virus (HAV) infection poses a significant public health risk, particularly in endemic regions.
- Effective prophylaxis is crucial for preventing HAV transmission and its associated morbidity.
Purpose of the Study:
- To review the indications, dosages, and efficacy of two new inactivated hepatitis A vaccines.
- To identify key populations recommended for hepatitis A vaccination.
Main Methods:
- Review of clinical trial data and manufacturer guidelines for two inactivated hepatitis A vaccines: Vaqta and Havrix.
- Analysis of recommended vaccination schedules for adults and children.
- Identification of high-risk groups for HAV infection.
Main Results:
- Two inactivated hepatitis A vaccines, Vaqta and Havrix, provide long-term protection and are indicated for pre-exposure prophylaxis in individuals over two years of age.
- Specific dosing schedules are outlined for adults and children for both vaccine preparations.
- Seroconversion rates exceeding 95% were observed in healthy children and adults, with vaccines deemed safe for use during pregnancy.
Conclusions:
- New inactivated hepatitis A vaccines offer a safe and effective means of preventing hepatitis A infection.
- Widespread vaccination is recommended for travelers, children in high-prevalence areas, and individuals with specific risk factors.
- Vaccination strategies should consider age-specific dosing and schedules to maximize long-term immunity.
Abstract:
Two new inactivated hepatitis A vaccines are available that confer long-term protection against infection. They are indicated for pre-exposure prophylaxis in persons older than 2 years of age. For one vaccine preparation, Vaqta (Merck and Co., West Point, PA), the recommended schedule for adults is a 1.0-mL (50 U of hepatitis A viral antigen) intramuscular dose initially, followed by a booster dose 6-12 months later. Children 2-17 years of age should receive 0.5 mL (25 U of hepatitis A viral antigen) initially, followed by a booster dose 6-18 months later. The adult dosage schedule for Havrix (SmithKline Beecham, Philadelphia, PA) is a 1.0-mL (1440 enzyme-linked immunosorbent assay [ELISA] units) intramuscular dose initially, followed by a 1.0-mL booster dose 6-12 months later. Patients 2-18 years of age should receive doses of 0.5 mL (720 ELISA units). Primary candidates for vaccination are travelers to regions of endemic disease, children living in high-prevalence areas, homosexual males, users of illicit intravenous drugs, persons working directly with nonhuman primates or hepatitis A virus, patients older than 30 years of age with chronic liver disease, and persons who have received a liver transplant or are awaiting one. Seroconversion rates in healthy children and adults exceed 95%. Both vaccines are safe for use in pregnancy. The cost of the vaccine for adult patients is approximately $50 to $60.