RT Journal Article SR Electronic(1) A1 van der Werf, S A1 Lévy-Bruhl, D YR 2015 T1 Influenza – the need to stay ahead of the virus JF Eurosurveillance VO 20 IS 5 SP 21030 OP DO https://doi.org/10.2807/1560-7917.ES2015.20.5.21030 UL https://www.eurosurveillance.org/content/10.2807/1560-7917.ES2015.20.5.21030