Over the last year there have been more studies determining predisposition to severe bronchiolitis and its consequences. Studies have highlighted various single-nucleotide polymorphisms (SNPs) to be significantly associated with respiratory syncytial virus (RSV) hospitalisation, and a candidate gene approach demonstrated that innate immune gene SNPs had the strongest association with bronchiolitis. The impact of \'other\' viruses (RSV, influenza, adenovirus, parainfluenza, rhinovirus, human metapneumovirus [hMPV], coronavirus, boca-virus, enterovirus, paraechovirus) has been investigated. In one series only children with RSV infection experienced recurrent wheezing and in another only RSV infection was associated with respiratory complications (hypoxia correlated with prolonged hospitalisation). Others have examined the long-term outcome of viral infection in infancy. The above studies and others published in the last year will be discussed.