A team from Maryland, USA, examined the effect of a rotavirus vaccination program (Rotashield) on infant intussusception hospital admissions.
Electronic databases, containing 100% hospital discharge records for 1993-1999 from 10 US states, were examined. Among these, an estimated 28% of the birth cohort had received Rotashield (based on manufacturer's net sales data).
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The researchers examined records of infants admitted to hospital (younger than a year old) with any mention of intussusception.
Excess admissions for intussusception during the period of Rotashield availability (October 1998-June 1999) were estimated. This was done by direct comparison with the corresponding period of October 1997-June 1998 (before Rotashield was available), and with adjustment for secular trends during 1993-1998 by Poisson regression.
It was found that hospital admission for intussusception during the Rotashield period, compared with previously, was 4% lower (10 cases) by direct comparison and 10% lower (27 cases) by trend comparison.
Among infants aged 45-210 days (target age range for a first Rotashield dose), the researchers estimated an increase in intussusception admissions. The increase was found to be 1% (1 excess admission) by direct comparison and 4% (4·6 excess admissions) by trend comparison. This corresponded to a population attributable risk range of 1 excess admission in every 66,000-302,000.
Dr Lone Simonsen, of the National Institute of Allergy and Infectious Diseases, Bethesda, Maryland, said on behalf of the group, "We found no evidence of increased infant intussusception admissions during the period of Rotashield availability."
"The total intussusception admission risk attributable to Rotashield was substantially lower than previous estimates, based on studies focusing on the immediate postvaccination weeks," it was concluded.