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Summary: Background: The characteristics of nosocomial influenza in children are not well described. Aim: To compare the characteristics of nosocomial and community-acquired pandemic influenza A (H1N1) 2009 (pH1N1) in Australian children. Methods: In a nested case–control study, the clinical and epidemiological features of nosocomial vs community-acquired pH1N1 were compared among hospitalized children aged <15 years in six paediatric hospitals in Australia between 1 June and 30 September 2009. Findings: Of 506 hospitalized children with pH1N1, 47 (9.3%) were of nosocomial origin. These 47 cases were compared with 141 gender- and age-matched controls. Cases had a significantly higher proportion of underlying medical conditions compared with controls (81% vs 42%, P < 0.001), and were more likely to be exposed to household smokers (36% vs 20%, P = 0.02). Fewer children with nosocomial influenza presented with classical symptoms of influenza, including subjective fever and lethargy. A higher proportion of children with nosocomial influenza received treatment with oseltamivir (77% vs 43%, P < 0.001), and they required a longer stay in hospital following the onset of influenza (mean 8.5 days vs 4.5 days, P = 0.006). Three children (2%) in the community-acquired group died of pH1N1, but there were no deaths in the nosocomial group. Conclusion: This study shows that children with pre-existing diseases and those who are exposed to household smokers are more susceptible to nosocomial pH1N1. They may have ‘occult presentation’ of influenza, but their course of illness is not markedly different from that of children with community-acquired influenza. [Copyright &y& Elsevier]

Abstract: Introduction: In Australia, post-marketing surveillance for intussusception following vaccination commenced with funding of RotaTeq ® and Rotarix ® vaccines under the National Immunization Program (NIP) in July 2007. Methods: Two active surveillance mechanisms (hospital-based case ascertainment and monthly reports from paediatricians) identified intussusception cases between 1st July 2007 and 31st December 2008 in four states. Linkage to vaccination records identified cases occurring within 1–7 and 1–21 days of rotavirus vaccination. Expected cases within the post-vaccination windows were calculated by applying rates of intussusception from national hospitalisation data over 6 years (mid-2000 to mid-2006), by age and state, to numbers vaccinated (by dose) according to the Australian Childhood Immunization Register. Results: Combining exposure windows associated with all doses of rotavirus vaccine from 1 to 9 months of age, there was no evidence of an increased risk of intussusception following vaccination for either vaccine. However, in infants 1 to <3 months of age, there was suggestive evidence of excess intussusception cases 1–7 and 1–21 days following dose 1 (1–7 days: RotaTeq ® relative risk (RR)=5.3, 95% confidence interval [CI] 1.1,15.4; Rotarix ® RR 3.5, 95% CI 0.7,10.1; 1–21 days: RotaTeq ® RR 3.5, 95% CI 1.3, 7.6; Rotarix ® RR 1.5, 95% CI 0.4, 3.9). There was no evidence that clinical outcome of intussusception occurring within 21 days of rotavirus vaccination differed from that in cases occurring later post-vaccination. Conclusion: Although we found no overall increase in intussusception following receipt of rotavirus vaccine, there was some evidence of an elevated risk following the first dose of both vaccines. Larger population-based studies using linked databases are required to provide more definitive evidence. [Copyright &y& Elsevier]