RT Journal Article SR Electronic(1) A1 Duffell, E A1 EspiƩ, E A1 Nichols, T A1 Adak, G K A1 de Valk, H A1 Stuart, J M YR T1 JF VO OP UL https://www.eurosurveillance.org/content/10.2807/esm.08.04.00406-fr