Background RotaTeq was introduced into the Australian National Immunisation Program in 2007. This study identified and characterised rotavirus strains excreted by infants who presented with symptoms of gastroenteritis following recent RotaTeq vaccination.

Methods Faecal samples (n=61) from children who developed gastroenteritis following recent RotaTeq vaccination were forwarded to the Australian Rotavirus Surveillance Program (ARSP). RotaTeq positive samples were genotyped and regions of the VP3, VP4, VP6 and VP7 genes were sequenced. Also, 460 rotavirus positive ARSP routine surveillance samples were analysed by dot-blot Northern hybridisation to detect RotaTeq vaccine-derived strains circulating in the community.

Results Thirteen of the 61 samples collected from infants developing gastroenteritis after RotaTeq vaccination contained vaccine-derived rotavirus strains. Of these, four contained a vdG1P[8] strain derived by reassortment between the G1P[5] and G6P[8] parental vaccine strains. Northern hybridisation analysis of 460 surveillance samples, identified three samples that contained RotaTeq vaccine-derived strains, including two vdG1P[8] reassortant vaccine strains.

Conclusions During replication and excretion of RotaTeq, reassortment of parental strains can occur. Shedding of RotaTeq vaccine strains in seven out of 13 infants was associated with underlying medical conditions that may have altered their immune function. The benefits of vaccination outweigh any small risk of vaccine-associated gastroenteritis.

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