The risk of intussusception following monovalent rotavirus vaccination in England: A self-controlled case-series evaluation.

OBJECTIVE

To investigate the risk of intussusception after monovalent rotavirus vaccine (RV1) given to infants aged 2 and 3 months in England.

METHODS

Hospital Episode Statistics (HES) were used to identify infants aged 48-183 days admitted between 11/03/2013 and 31/10/2014 with intussusception. Diagnosis was confirmed from medical records and HES procedure codes. Vaccination status was obtained from general practitioners. The risk of admission within 1-7 and 8-21 days of vaccination was analysed using the self-controlled case-series (SCCS) method with age effect adjustment by including historical data before RVI introduction in July 2013.

RESULTS

A total of 119 cases were identified during the study period and intussusception confirmed in 95 of whom 39 were vaccinated 1-21 days before onset. An increased relative incidence (RI) in this period was found, 4.53 (95% confidence interval 2.34-8.58) and 2.60 (1.43-4.81) respectively after the 1st and 2nd doses with an attributable risk of 1.91 and 1.49 per 100,000 doses respectively. The peak risk was 1-7 days after the first dose, RI 13.81 (6.44-28.32), with an estimated 93% of the 15 cases being vaccine-attributable. Mean interval between onset and admission, and clinical features were similar between vaccine-associated and background cases. Despite intussusception being a contraindication to rotavirus vaccination, 10 infants received a further dose; none had a recurrence. The RIs in a meta-analysis combing our results with Australia, Mexico, Brazil and Singapore using RV1, a 2, 4 month schedule and SCCS gave pooled RI estimates of 2.35 (1.45-3.8) and 1.77 (1.29-2.43) in the 21 day period after the 1st and 2nd doses, respectively. The earlier age at the 2nd dose in England did not affect the risk.

CONCLUSION

We estimate that the RVI programme causes around 21 intussusception admissions annually in England but, since it prevents around 25,000 gastro-intestinal infection admissions, its benefit/risk profile remains strongly positive.