P367 To switch or not to switch: the benefit of quadrivalent influenza vaccine to the Irish paediatric population

Background Until recently, trivalent influenza vaccines (TIV) have contained one influenza B virus, recommended annually by the WHO vaccine selection committee. Quadrivalent Influenza Vaccines (QIV) add protection against a second B lineage; preventing the threat of a vaccine mismatched season, which often occurs in the Northern Hemisphere, leading to reduced vaccine effectiveness (VE) and increased influenza morbidity and mortality. Young children have one of the highest clinical burdens in Ireland, with the highest age-specific rate for influenza cases admitted to critical care units generally in children aged 0–4 years. Additionally, school-aged children are a major source of community transmission. Aim To assess the benefit of a QIV in the Irish paediatric population. Methods A literature review was conducted comparing QIV to TIV, focusing on VE and cost-effectiveness (CE). The VE of live-attenuated influenza vaccine (LAIV) compared to inactivated influenza vaccine (IIV) in children was also studied. The Cochrane database of systematic reviews, the Cochrane Central Register of Controlled Trials, PubMed, the Lancet, and publications from the European projects I-MOVE/I-MOVE+ and VENICE were searched for publications between 2009–2018. Results Recent influenza seasons suggest a higher VE of QIV compared to TIV. Studies have shown that QIV is as effective as TIV for the strains included in both; however QIV has superior immunogenicity for the additional B strain when there is a mismatch season. These results are also reflected in pre-licensing studies of the immunogenicity of QIVs that are now approved. LAIV has been recommended due to higher VE against influenza B strains and the ease and acceptability of the intranasal vaccination compared to the injectable IIV. QIV are more expensive than TIV, however CE analyses indicate that QIV delivers substantial savings in terms of preventing direct healthcare costs through reductions in infection numbers, hospitalisations and deaths; resulting in quality-adjusted life years gained. There are also substantial societal benefits through indirect savings in productivity (preventing employee/caregiver absences). Rolling out QIV to children was the most cost-effective vaccination strategy in the UK (aged 2–11 years) and in European countries (4–16 years) partaking in the I-MOVE+ project, with the exception of Portugal. Conclusion QIV would stabilise the VE across influenza seasons; eliminating the uncertainty of predicting the influenza B lineage, ultimately increasing public confidence in the vaccine, resulting in increased vaccine uptake. Broader protection in the paediatric population would directly reduce influenza transmission and indirectly protect vulnerable populations in the community.