Introduction of a quadrivalent influenza vaccine in Italy: a budget impact analysis

Every year in Italy, the Ministry of Health (MoH) offers influenza vaccination free of charge to all subjects at risk and to all subjects aged ≥ 65 year old. Until 2014-2015 immunization campaign against Trivalent Influenza Vaccine (TIVs) were the only vaccines used in Italy. Traditional TIVs contain antigens from three viral strains: A(H1N1), A(H3N2), and one of the two B lineages: B(Victoria) or B(Yamagata). Each year, the World Health Organization (WHO) decides which viral strains should be included in the next seasonal influenza vaccine. However, accurately predicting which B-lineage strain will predominate in the upcoming season has proved to be a challenging task, owing to the co-circulation of both lineages. To address the issue of B-mismatch, a new Quadrivalent Influenza Vaccine (QIV) containing both B-lineage strains has been developed, in order to achieve broader protection against influenza. The new QIV was approved in Italy in 2015 and included by the MoH in the national recommendations for the seasonal immunization campaign against influenza 2015-2016. Recently, a Health Technology Assessment (HTA) Report has shown that, in comparison with TIVs, the new QIV is cost-effective (Incremental Cost-Effectiveness Ratio (ICER) = € 18,883/ (QALY) Quality-Adjusted Life-Year) from the Italian National Health Service (NHS) perspective. The present Budget Impact Analysis (BIA) showed that the introduction of the QIV with a 9% market share in the vaccine mix for the 2015-2016 flu campaign would yield an annual saving of € 674,089, mainly owing to the broader protection offered by QIV vs TIVs with an estimated 49.12% B-mismatch.