Interim 2018/19 influenza vaccine effectiveness: six European studies, October 2018 to January 2019

European IVE Group - Portuguese Team: Verónica Gomez, Irina Kislaya, Baltazar Nunes, Ana Paula Rodrigues Ausenda Machado (Departamento de Epidemiologia, Instituto Nacional de Saúde Doutor Ricardo Jorge); Patrícia Conde, Inês Costa, Paula Cristóvão, Pedro Pechirra, Raquel Guiomar (Departamento de Doenças Infeciosas, Instituto Nacional de Saúde Doutor Ricardo Jorge).Seasonal influenza vaccine is recommended in all European Union (EU) countries for older people and others at increased risk of severe influenza and its complications, including those with chronic diseases. In the United Kingdom (UK), incremental introduction of a universal childhood influenza vaccination programme began in 2013/14. The World Health Organization (WHO) recommendations for trivalent influenza vaccine strains for the 2018/19 northern hemisphere influenza season included an A/Michigan/45/2015 (H1N1)pdm09-like virus, an A/Singapore/INFIMH-16–0019/2016 (H3N2)-like virus and a B/Colorado/06/2017-like virus from the B/Victoria lineage. The early 2018/19 influenza season in Europe was characterised by both influenza A virus subtypes circulating widely. There was co-circulation in some countries, with others reporting dominance of either A(H1N1)pdm09 or A(H3N2) viruses. The season started late in most countries compared with previous seasons, with few influenza B viruses detected in the WHO European Region. Since the 2008/09 season, the UK, Denmark, Spain, and several other EU countries conducting multicentre studies, have participated in I-MOVE (Influenza – Monitoring Vaccine Effectiveness in Europe), a network measuring influenza vaccine effectiveness each season. Interim results from six established influenza VE studies across Europe for the 2018/19 season indicate that VE against laboratory-confirmed influenza A ranged between 32% and 43% among all ages in primary care and hospital settings and was 59% in the target groups for vaccination.ECDC