ABSTRACT
Introduction: Understanding baseline epidemiology of intussusception (IS) in different geographical settings is important for the safety assessment of rotavirus vaccines. This paper presents IS surveillance data from Singapore between 1997 and 2007, including the period between November 2005 and December 2007 when rotavirus vaccines (primarily Rotarix™) were available to newborns in Singapore. Materials and Methods: Case ascertainment, collection, analyses and presentation of IS data was done as per recommendations of the Brighton Collaboration Working Group. For estimating the IS incidence rate in infants, live births for the years of the study were used as denominators, while for incidence in children age <2 years, the expected numbers of infant deaths occurring between 1 and 2 years of age was deducted from the combined live births for the 2 years, to obtain the denominator. Results: The incidence of IS among children aged <1 year throughout this 10-year period was higher than the incidence of IS in children between 1 and 2 years of age. In 2005, 2006 and 2007, the incidence of IS per 100,000 was 39.9, 26.4 and 35.6 in children aged <1 year and 26.2, 23.8 and 28.7 in children <2 years. Conclusion: This IS surveillance study provides reassuring preliminary evidence that there is no increase in the incidence of IS in Singapore after the introduction of rotavirus vaccines (including Rotarix™) in Singapore.
This is an update to the previously published paper by Boudville et al1 on 8 years of intussusception (IS) surveillance in Singapore. IS is a rare but serious gastrointestinal disease in infants and young children.2,3 The focus on natural rotavirus infection as a potential cause of IS followed the discovery of an association between the first generation rotavirus vaccine Rotashield™ (Wyeth-Lederle) and IS in the US.4,5 The link between Rotashield™ and IS was noted through the Vaccine Adverse Event Reporting System (VAERS) within a year of the vaccine being licensed.4,5 Epidemiological investigations detected a statistically significant increased risk of IS, leading to the reversal of the recommendation by the ACIP (Advisory Committee on Immunization Practices) and the withdrawal of Rotashield™ by its manufacturer.4,5 Nevertheless, despite intense scrutiny in recent years, naturally occurring rotavirus infection – the most common cause of childhood diarrhoea – has remained unproven as a cause of IS.6-8
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