1392 - Evaluation of the Impact of a Single-dose Hepatitis A Vaccination in Brazil: a time-series analysis

Background: Brazil has transitioned from an intermediate to low hepatitis A virus endemic country, increasing the risk of severe Hepatitis A (HepA) disease. To control transmission, the HepA vaccine, MSD, was introduced in the National Childhood Immunization Program (NIP) in 2014 for children aged 12-24 months and extended to children under 5 years old in 2017. We evaluated the impact of the vaccination on the HepA incidence, associated healthcare resource utilization (HCRU), and costs.

Methods: We conducted an observational, retrospective study using Brazilian National Public Health Data (DATASUS). An interrupted time-series analysis was conducted for incidence rates (IR) of laboratory- or clinically-confirmed Hep A cases. Using a negative binomial regression model, we assessed changes in annual HepA IR between pre- (2010-2013) and post- (2015-2018) HepA vaccination periods and compared to predicted counterfactual rates without HepA vaccination. We compared HCRU and cost of Hep A-associated hospitalizations and outpatient procedures between pre- and post- HepA vaccination periods.

Results: Between 2010 and 2018, 32,295 Hep A cases occurred across all ages. Among the NIP target children aged 1-4 years, HepA vaccination was associated with an immediate HepA IR decrease (-52,5% of level change) and with a decrease in slope (-7.7% vs -67.6% per year for pre- and post-periods, respectively, Figure 1). We observed a similar trend in non- HepA vaccination target children aged 5-14 years with -57.1% of level change and slope change from -3.4% (pre- HepA vaccination) to -53.7% (post- HepA vaccination) per year (Table 1). Across all age groups, 14,468 Hep A cases were averted when compared to predicted counterfactual rates (Table 2). Overall, HepA-related hospitalization rate dropped 64% after NIP introduction of vaccination resulting in a cost reduction of 55%. The total number of outpatient procedures claimed among HepA-diagnosed patients reduced 18% with 42% cost reduction.Figure 1: time-series analyses of Hepatitis A incidence rate (IR) for NIP target population. Monthly number of hepatitis A cases observed over the study period (black line). Predicted trend based on the pre- HepA vaccination (red line) and post- HepA vaccination (blue line) monthly cases
Table 1: Time-series analysis of the impact of the hepatitis A vaccination on the incidence rate level of change, according to age group
Table 2: Number of observed, predicted counterfactual, and averted hepatitis A cases in the post- HepA vaccination period (2015-2018), according to age group.


Conclusion: In Brazil, the single-dose hepatitis A vaccine childhood program effectively reduced the   Hepatitis A incidence, HCRU and associated-costs in vaccinated and in some non-vaccinated age groups.