HAVRIX 1440 Dosing for a 19-Year-Old
For a healthy 19-year-old, administer HAVRIX 1440 EL.U. (1.0 mL) intramuscularly in the deltoid muscle as a two-dose series, with the second dose given 6-12 months after the initial dose. 1, 2
Dosing Regimen
- Initial dose: 1440 EL.U. (1.0 mL) intramuscularly 1, 2
- Booster dose: 1440 EL.U. (1.0 mL) given 6-12 months after the first dose 1, 3
- Route: Intramuscular injection into the deltoid muscle with appropriate needle length 1
Expected Immune Response
The immunogenicity data strongly support this regimen:
- After first dose: More than 96% of adults aged 18-50 years seroconvert within 1 month, with 80-98% already seroconverted by day 15 2
- After second dose: 100% of vaccinees achieve seroprotection, with geometric mean titers (GMTs) ranging from 3,318 to 5,925 mIU/mL 2
- Rapid protection: The CDC notes that after completing the two-dose schedule, virtually 100% of individuals are protected against hepatitis A infection 4
Flexibility in Booster Timing
While the recommended interval is 6-12 months, there is flexibility if the patient misses this window:
- Delayed booster acceptable: Research demonstrates that booster doses given up to 66 months after the primary dose still produce robust anamnestic responses 5
- No need to restart: If the immunization schedule is interrupted, simply administer the missing dose rather than restarting the series 1, 3
- Maintained protection: Studies show protective antibody levels can persist for almost 11 years after a single dose, though the two-dose series is still recommended for optimal long-term immunity 1
Administration Guidelines
- Preparation: Shake the vaccine well before administration; it should appear as a slightly opaque, white suspension 1, 2
- Storage: Keep refrigerated at 2-8°C (36-46°F); never freeze as this destroys vaccine potency 1, 3
- Site: Deltoid muscle is the standard site for adults 1, 4
Clinical Pearls
- No serologic testing needed: Pre-vaccination or post-vaccination antibody testing is not recommended for routine immunization 3
- Interchangeability: Different hepatitis A vaccine brands (HAVRIX, VAQTA) are interchangeable for completing the series, though this is not typically necessary 3
- Safety profile: Millions of doses have been administered since 1995 with no significant adverse events beyond mild injection-site reactions, fever, and occasional mild diarrhea 1