Pre-licensure studies of GSK Biologicals' PEDIARIX vaccine have shown it to be generally safe and unlikely to result in vaccine-associated serious adverse events. This post-licensure study is designed to evaluate relatively uncommon/rare outcomes in a large population cohort.

• The outcomes to be assessed include the occurrence of all seizures (with or without fever), medically-attended fever, seizures associated with fever, allergic reactions, outpatient visits and hospitalizations for any cause, and all deaths.
• Data collection through utilization of automated databases at the study site with subset medical record review. The Protocol Posting has been updated in order to comply with the FDA Amendment Act, Sep 2007.

Inclusion criteria:

Primary study cohort

The primary study cohort will include all infants from SCKP who have begun their primary course of vaccine with PEDIARIX co-administered with Prevnar and for whom at least one dose of PEDIARIX was administered prior to the infant's 9-month birthday and safety follow-up information is available.

Control cohorts

Three control cohorts will be evaluated.

1. The historical cohort will include age-, gender- and area-matched infants from SCKP who received at least one dose of DTaP vaccine co-administered with Prevnar prior to the infant's 9-month birthday and for whom safety follow-up information is available. This cohort will include infants vaccinated between January, 2002 and March, 2003.
2. The self-control cohort is defined for the study subject as the 20-day post-vaccination period from Day 21 to Day 41 for each infant in the primary cohort (PEDIARIX co-administered with Prevnar as the primary vaccination course).
3. The "delayed PEDIARIX use clinic" cohort will include all infants from SCKP who, during the enrollment period for the primary cohort, began their primary course of vaccination with DTaP vaccine and for whom at least one dose of DTaP vaccine was co-administered with Prevnar prior to the infant's 9-month birthday and safety follow-up information is available. The size of this cohort will depend on how quickly individual SCKP clinics and medical centers use PEDIARIX once it is made available. The size of this cohort, therefore, is not immediately predictable.

Exclusion Criteria: none

The study will be conducted by the University of California, Los Angeles (UCLA) Center for Vaccine Research (CVR) and the Southern California Kaiser Permanente Health Care Plan (SCKP), the largest Health Maintenance Organization (HMO) in California.

All infants who receive at least one dose of PEDIARIX in the primary series will be identified through the automated Kaiser Immunization Tracking System (KITS).