Immunogenicity of the hepatitis A vaccine 20 years after infant immunization. Issue 32 (6th July 2020)

• Record Type: Journal Article
• Authors: Mosites, E.; Seeman, S.; Negus, S.; Homan, C.; Morris, J.; Nelson, N.P.; Spradling, P.R.; Bruce, M.; McMahon, B.
• Is Part Of: Vaccine. Volume 38:Issue 32(2020)
• Page Start: 4940
• Page End: 4943
• Publication Date: 2020-07-06
• Subjects: Hepatitis A vaccine -- Infant -- Immunogenicity; Vaccines -- Periodicals; 615.372
• DOI: 10.1016/j.vaccine.2020.05.069
• Languages: English
• ISSNs: 0264-410X

Abstract

Highlights: We evaluated Hepatitis A vaccine immunogenicity 20 years after infant vaccination. Hepatitis A vaccine seropositivity was identified among 68% of participants. We predict 50% of participants will no longer be seropositive by 27 years of age. Studies are needed to determine if protection against Hepatitis A will also be lost. Abstract: To determine the duration of immunity provided by the Hepatitis A vaccination (HepA), we evaluated a cohort of participants in Alaska 20 years after being immunized as infants. At recruitment, participants received two doses of inactivated HepA vaccine on one of three schedules. We conducted hepatitis A antibody (anti-HAV) testing for participants at the 20-year time-point. Seventy-five of the original 183 participants (41%) were available for follow-up. The overall anti-HAV geometric mean concentration was 29.9 mIU/mL (95% CI 22.4 mIU/mL, 39.7 mIU/mL) and 50 participants (68%) remained seropositive (titer ≥ 20 mIU/mL). Using a fractional polynomial model, the predicted percent seropositive at 25 years was 55.3%, 49.8% at 30 years and 45.7% at 35 years, suggesting that the percent sero-positive could drop below 50% earlier than previously expected. Further research is necessary to understand if protection continues after seropositivity diminishes or if a HepA booster dose may become necessary.