Postmarketing surveillance of intussusception following mass introduction of the attenuated human rotavirus vaccine in Mexico.
BACKGROUND
Mexico initiated mass vaccination with the attenuated human rotavirus vaccine (Rotarix) in 2006. This postlicensure study aimed to assess any potential temporal association between vaccination and intussusception in Mexican infants.


METHODS
Prospective, active surveillance for intussusception among infants aged less than 1 year was conducted in 221 hospitals across Mexico from the Mexican Institute of Social Security between January 2008 and October 2010. The temporal association between vaccination and intussusception was assessed by self-controlled case-series analysis.


RESULTS
Of the 753 episodes of intussusception reported in 750 infants, 701 were in vaccinated infants (34.5% post-dose 1, 65.5% post-dose 2). The relative incidence of intussusception within 31 days of vaccination was 1.75 (95.5% confidence interval [CI]: 1.24-2.48; P=0.001) post-dose 1 and 1.06 (95.5% CI: 0.75-1.48; P=0.75) post-dose 2. The relative incidence of intussusception within 7 days of vaccination was 6.49 post-dose 1 (95.5% CI: 4.17-10.09; P<0.001) and 1.29 post-dose 2 (95.5% CI: 0.80-2.11; P=0.29). Clustering of intussusception within 7 days of vaccination was observed post-dose 1. An attributable risk of 3 to 4 additional cases of intussusception per 100,000 vaccinated infants was estimated.


CONCLUSIONS
This is the largest surveillance study for intussusception after rotavirus vaccination to date. A temporal increase in the risk for intussusception was seen within 7 days of administration of the first vaccine dose. It is still uncertain whether rotavirus vaccination has any impact on the overall incidence of intussusception. This finding has to be put in perspective with the well-documented substantial benefits of rotavirus vaccination.
Medical Research Unit on Infectious Diseases, Pediatrics Hospital, National Medical Center-Century-XXI, Mexican Institute of Social Security (IMSS), Mexico City, Mexico. fraulv@infosel.net.mx
F Raúl
FR
Velázquez
Romulo E
RE
Colindres
Concepción
C
Grajales
M Teresa
MT
Hernández
María Guadalupe
MG
Mercadillo
F Javier
FJ
Torres
MariaYolanda
M
Cervantes-Apolinar
Rodrigo
R
DeAntonio-Suarez
Eduardo
E
Ortega-Barria
Maxim
M
Blum
Thomas
T
Breuer
Thomas
T
Verstraeten
D064420:Drug-Related Side Effects and Adverse Reactions / Q000453:epidemiology*; D005260:Female; D006801:Humans; D007223:Infant; D007443:Intussusception / Q000139:chemically induced* / Q000453:epidemiology*; D008297:Male; D008800:Mexico / Q000453:epidemiology; D011358:Product Surveillance, Postmarketing; D011446:Prospective Studies; D012400:Rotavirus Infections / Q000517:prevention & control; D022243:Rotavirus Vaccines / Q000008:administration & dosage* / Q000009:adverse effects*; D014613:Vaccines, Attenuated / Q000008:administration & dosage / Q000009:adverse effects
C492457:RIX4414 vaccine; D022243:Rotavirus Vaccines; D014613:Vaccines, Attenuated