Intussusception after monovalent rotavirus vaccine-United States, Vaccine Adverse Event Reporting System (VAERS), 2008-2014.
BACKGROUND
In 2006 and 2008, two new rotavirus vaccines (RotaTeq [RV5] and Rotarix [RV1]) were introduced in the United States. US data on intussusception have been mostly related to RV5, with limited data on RV1.


METHODS
We assessed intussusception events following RV1 reported to the Vaccine Adverse Event Reporting System (VAERS), a US national passive surveillance system, during February 2008-December 2014. We conducted a self-controlled risk interval analysis using Poisson regression to estimate the daily reporting ratio (DRR) of intussusception after the first 2 doses of RV1 comparing average daily reports 3-6 versus 0-2 days after vaccination. We calculated the excess risk of intussusception per 100,000 vaccinations based on DRRs and background rates of intussusception. Sensitivity analyses were conducted to assess effects of differential reporting completeness and inaccuracy of baseline rates.


RESULTS
VAERS received 108 confirmed insusceptible reports after RV1. A significant clustering was observed on days 3-8 after does1 (p=0.001) and days 2-7 after dose 2 (p=0.001). The DRR comparing the 3-6 day and the 0-2 day periods after RV1 dose 1 was 7.5 (95% CI=2.3, 24.6), translating to an excess risk of 1.6 (95% CI=0.3, 5.8) per 100,000 vaccinations. The DRR was elevated but not significant after dose 2 (2.4 [95% CI=0.8,7.5]). The excess risk ranged from 1.2 to 2.8 per 100,000 in sensitivity analysis.


CONCLUSIONS
We observed a significant increased risk of intussusception 3-6 days after dose 1 of RV1. The estimated small number of intussusception cases attributable to RV1 is outweighed by the benefits of rotavirus vaccination.
Immunization Safety Office, Division of Healthcare Quality Promotion, National Center for Emerging and Zoonotic Infectious Diseases (NCEZID), Centers for Disease Control and Prevention (CDC), United States. Electronic address: phaber@cdc.gov.
Penina
P
Haber
National Center for Immunizations and Respiratory Diseases, CDC, United States.
Umesh D
UD
Parashar
Emory University, Rollins School of Public Health, Biostatistics and Bioinfomatics, United States.
Michael
M
Haber
Immunization Safety Office, Division of Healthcare Quality Promotion, National Center for Emerging and Zoonotic Infectious Diseases (NCEZID), Centers for Disease Control and Prevention (CDC), United States.
Frank
F
DeStefano
D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D007443:Intussusception / Q000139:chemically induced* / Q000453:epidemiology*; D008297:Male; D018570:Risk Assessment; D022243:Rotavirus Vaccines / Q000008:administration & dosage* / Q000009:adverse effects*; D014481:United States / Q000453:epidemiology; D014613:Vaccines, Attenuated / Q000008:administration & dosage / Q000009:adverse effects
C492457:RIX4414 vaccine; D022243:Rotavirus Vaccines; D014613:Vaccines, Attenuated
Intussusception; Rotarix vaccines; Safety monitoring; Vaccine adverse event