Dramatic reduction in hepatitis B through school-based immunization without a routine infant program in a low endemicity region

Teegwendé Valérie Porgo, Vladimir Gilca, Gaston De Serres, Michèle Tremblay, Danuta Skowronski

Hepatitis B (HB) prevention in the low-endemicity province of Quebec Canada, (population: ~8.2 million; birth cohort ~85,000/year), includes two decades of pre-adolescent school-based immunization, as well as catch-up immunization for those born since 1983 and pre-natal maternal HBsAg screening. To estimate the potential added benefit of routine infant HB immunization, notifiable disease reports were analyzed (1990-2013). Clinical and demographic information about cases was retrieved from standard questionnaires used by local public health units to investigate HB cases. The Quebec provincial registry of notifiable diseases was used to identify confirmed HB cases reported between 1990 and 2013. Clinical and demographic information on cases was retrieved from the standard questionnaires used by local public health units to investigate reported HB cases. Between 1990-2013, acute-HB incidence per 100,000 population decreased by 97 % from 6.5 to 0.2. Compared to 1990, incidence fell from 0.6 to zero since 2010 among children ≤9 years of age (yoa), from 3.2 to zero since 2007 in those 10-19 yoa, and from 15 to zero in 2013 among adults 20-29 yoa, previously the age group of highest incidence (all p < 0.0001). During the same period, the newly-reported chronic HB rate per 100,000 decreased by 66 % from 17.7 to 6.1 (p < 0.0001), with a reduction of 92 % (2.4 to 0.2;p < 0.001) in children ≤9 yoa and 83 % (7.2 to 1.2;p = 0.003) in those 10-19 yoa. The incidence of unspecified HB cases did not decrease significantly overall (5.9 vs. 5.4; p = 0.24), in children ≤ 9 yoa (0.3 vs. 0.2;p = 0.70) or 10-19 yoa (1.6 vs. 1.5;p = 0.45). Overall, 91 % of cases ≤19 yoa were immigrants likely infected before arrival in Canada. Among those ≤9 yoa, there were 9 acute-HB case reports between 2005 and 2013, of whom 8 were not preventable by infant immunization. Two decades of school-based immunization coupled with prenatal screening achieved striking reduction in disease burden in the low-endemicity province of Quebec, Canada. The oldest cohorts targeted by catch-up campaigns are now beyond the average age at childbirth so that neo-natal transmission and the potential incremental benefit of infant immunization will likely further diminish.