Influenza, vaccination, epidemiology, surveillance, evaluation, public health, vaccine effectiveness, policy recommendation, health protection
Purpose:
Quadrivalent influenza vaccines (QIV) provide broader protection against circulating influenza B/lineage
viruses than trivalent influenza vaccines (TIV). In Ireland, TIVs are the main vaccines in use. The 2017/2018
B/lineage vaccine mismatched season resulted in reduced influenza B vaccine effectiveness (VE) estimates and increased influenza mortality and morbidity. We reviewed the VE and cost-effectiveness (CE) of QIV, to assess the benefit of its introduction in Ireland.
Methods:
We conducted an extensive (non-systematic) literature review on Pubmed and the Cochrane library for articles
published between 2009-2018 on VE and CE of QIV and TIV. Additionally, we searched for publications by selected study groups estimating influenza VE.
Results:
Cross-lineage protection against influenza B/lineages not included in the TIV was reported during some B
mismatched seasons. Overall, QIV showed higher VE compared to TIV, but low VE for both vaccines was reported for older adults.
Despite the greater unit cost of QIV, CE modelling studies showed substantial savings with QIV through reductions in influenza cases, hospitalisations and deaths and also gains in quality-adjusted life years. The use of QIV for children combined with adjuvanted/high dose TIV in those aged ≥ 65 years, resulted as the most CE vaccination strategy.
Implications:
QIV can reduce the impact of a B/lineage vaccine mismatch, improving influenza B VE across seasons, which
may increase public confidence in influenza vaccine and lead to increased vaccine uptake. Preferential use of
QIV in children should assist in reducing influenza transmission and also indirectly protect vulnerable populations through herd immunity in Ireland.