This study estimated the potential impact of universal infant HAV vaccination in Mexico with two doses of Havrix™ at 12 and 18 mo of age on all HAV infections and symptomatic HAV infections. We developed a dynamic transmission model that accounts for changes in demography and HAV epidemiology. It was calibrated using Mexican age-specific seroprevalence and symptomatic HAV incidence data.
With 70% first-dose coverage and 85% second-dose coverage, the calibrated model projected that HAV vaccination would reduce the incidence of all HAV infections (symptomatic and asymptomatic) after the first 25 y of vaccination by 71–76% (minimum and maximum for different transmission scenarios). The projected reduction in cumulative incidence of symptomatic HAV infections over the first 25 y of vaccination was 45–51%. With 90% first-dose coverage and 85% second-dose coverage, the projected reduction in incidence of all HAV infections was 85–93%, and the projected reduction in the cumulative incidence of symptomatic HAV infections was 61–67%, over a 25-y time frame. Sensitivity analyses indicated that second-dose coverage is important under the conservative base-case assumptions made about the duration of vaccine protection.
The model indicated that universal infant HAV vaccination could substantially reduce the burden of HAV disease in Mexico.View Article
A single dose of the 3.75µg HA AS03-adjuvanted H1N1 2009 pandemic vaccine induced immune responses against the vaccine strain that met the European regulatory guidance criteria at day 21 in the elderly Japanese population; the immune response persisted at lower levels at month 6. No safety concerns were identified. These results suggest that two vaccine doses might be useful for the elderly population to improve antibody induction and persistence.Methods: In this open-label, single group study, 50 subjects received one dose of the 3.75 µg hemagglutinin (HA) AS03-adjuvanted H1N1 2009 vaccine. Immunogenicity assessments were made before vaccination, 21 days and six months after vaccination using hemagglutination inhibition (HI) and microneutralization assays. Immunogenicity end points were based on US and European regulatory criteria.View Article