Seventeen-year antibody persistence in adults primed with two doses of an inactivated hepatitis A vaccine

Abstract

Background and objectives: Antibody persistence and immune memory against hepatitis A (HAV) in adults in a low endemicity country, 15 y after immunization with two doses of HAV vaccine has been demonstrated. This communication provides additional information on antibody persistence up to Year 17 from two of the longest follow-up studies [NCT00289757/NCT00291876].Methods: In two double-blind primary studies, healthy adults aged 17240 y and 21240 y, respectively received two doses of the HAV vaccine following a 0,6 mo or 0,12 mo schedule. Anti-HAV antibody concentrations were measured using an enzyme-linked immunoassay (cut-off: 15 mIU/ml) at Year 16 and Year 17. Subjects who became seronegative (anti-HAV , 15 mIU/ml) since previous reporting were offered a challenge dose, with anti-HAV antibody concentration measurements at Day 14 and Day 30 thereafter.Results: At Year 17, 100% and 96.7% of subjects remained seropositive for anti-HAV antibodies following the 0, 6 mo and 0, 12 mo regimens, respectively (GMCs: 278 mIU/ml and 369 mIU/ml). One subject who became seronegative at Year 16 received a HAV challenge dose within the next 12 mo and mounted an anamnestic response. The challenge dose was well-tolerated.Conclusions: Both HAV immunization regimens (0,6 mo and 0,12 mo) induced persistence of vaccine-induced antibodies against HAV for at least 17 y after primary vaccination.

Model-based projections of the population-level impact of hepatitis A vaccination in Mexico

“…Individuals flowed mathematical modeling of antibody decay indicate that up to 95% to 97% of vaccinated adults are still protected against HAV infection up to 25 y after vaccination. [7][8][9] However, there are no data currently available on the long-term effectiveness of HAV vaccination in young children over the timescales involved in the present model, so for the base case of our model we used a conservative assumption of waning vaccine efficacy. For the period of 25 y after two doses, this was based on follow-up data and a mathematical model of antibody decay, [7][8][9] and for longer periods and after one dose the estimates were based on an earlier publication.…”

“…[7][8][9] However, there are no data currently available on the long-term effectiveness of HAV vaccination in young children over the timescales involved in the present model, so for the base case of our model we used a conservative assumption of waning vaccine efficacy. For the period of 25 y after two doses, this was based on follow-up data and a mathematical model of antibody decay, [7][8][9] and for longer periods and after one dose the estimates were based on an earlier publication. 17 Although, the estimates of two doses after first 25 y were derived from the opinion of an expert panel, 20 those estimates should be interpreted with caution.…”

“…After a full two-dose course of vaccination, models estimate that detectable anti-HAV antibodies would be expected to persist for at least 25 y after primary vaccination in 95% to 97% of recipients. [7][8][9] Universal infant HAV vaccination has been demonstrated to reduce the burden of hepatitis A disease in Israel, 10 Argentina, 11 and the US. 12 Mexico is currently considering the introduction of universal infant HAV vaccination, and thus it is important to evaluate the potential impact on the incidence of all HAV infections and symptomatic HAV infections in Mexico.…”

A retrospective pooled analysis assessing the effect of age on the immunogenicity ofHavrix™ in healthy adults

“…Of the total 80 subjects, one was taken from study 208109/108, 40 3 were taken from study 208109/114, 40 (Fig. 1).…”

“…[1][2][3] In addition, serologic evidence suggests that tens of millions of new HAV infections occur each year. 4,5 HAV also causes the second most common vaccinepreventable travel-associated infectious disease.…”