RT Journal Article SR Electronic(1) A1 Penttinen, Pasi M A1 Friede, Martin H YR 2016 T1 Decreased effectiveness of the influenza A(H1N1)pdm09 strain in live attenuated influenza vaccines: an observational bias or a technical challenge? JF Eurosurveillance VO 21 IS 38 SP 30350 OP DO https://doi.org/10.2807/1560-7917.ES.2016.21.38.30350 UL https://www.eurosurveillance.org/content/10.2807/1560-7917.ES.2016.21.38.30350