Intussusception Risk after Rotavirus Vaccination in Korean Infants

Background: An increased risk of intussusception after Rotavirus vaccination has been reported, with varying levels of risk associated with Rotarix and RotaTeq.

Objectives: To evaluate the risk of intussusception following Rotarix and RotaTeq in Korean infants.

Methods: We performed the self-controlled risk interval study using vaccination registry from the Korea Disease Control and Prevention Agency and the National Health Insurance Service claims data. This study included infants who received at least one dose of Rotarix or RotaTeq within 8 months of birth between June 1, 2016, and December 31, 2022. Intussusception event was defined as the first hospitalization for intussusception, identified using the ICD-10 code K56.1 and relevant surgical procedures codes. For each post-vaccination dose, the exposure risk intervals were defined as 1–7 days, 8–21 days, and 1–21 days with the control interval set at 22–42 days. Conditional Poisson regression model was used to estimate the adjusted incidence rate ratio (aIRR) with adjustments for age effects by the monthly interval. The attributable risk was calculated using aIRR estimates, with the attributable fraction determined as (aIRR-1)/aIRR for each risk period following each dose. This fraction was used to calculate the number of attributable cases, which was then divided by the estimated number of vaccine doses administered to the relevant population.

Results: Among the 792,581 infants who received the Rotarix, 167 cases of intussusception occurred within 42 days post-vaccination. In contrast, 290 cases were identified among the 805,492 infants administered with the RotaTeq during the same period. In Rotarix, the IRR in the risk intervals of 1–7 days was 2.48 (95% confidence interval [CI] 1.25–4.91) and 1.86 (95% CI 1.04–3.33) respectively after the first and second doses with an attributable risk of 1.97 (95% CI 0.66–2.63) and 1.48 (95% CI 0.12–2.25) per 100,000 doses. However, no statistically significant increase in intussusception risk was found during the risk intervals of 1–21 days and 8–21 days. No statistically significant increase in intussusception risk was observed for RotaTeq across all risk intervals.

Conclusions: There was an increase in the risk of intussusception within 7 days after the Rotarix vaccination, but no evidence of an increased risk of intussusception was found after the RotaTeq vaccination. Healthcare providers and parents should be informed about the potential risk associated with Rotarix and advised to closely monitor during the critical post-vaccination period.