Lack of association between receipt of conjugate Haemophilus influenzae type b vaccine (HbOC) in infancy and risk of type 1 (juvenile onset) diabetes: long term follow-up of the HbOC efficacy trial cohort


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We evaluated the effect of infant vaccination with HbOC Haemophilus influenzae type b (Hib) conjugate vaccine on the risk of onset of type 1 juvenile diabetes later in life by examining data from a large controlled prospective Phase III clinical efficacy trial conducted within Northern California Kaiser Permanente between 1988 and 1990. The overall study population included children who were offered the Hib conjugate vaccine (acceptors and refusers) as well as a cohort of children who were systemically excluded from the trial on the basis of their birth date. These children are now 10 to 12 years of age. We found no evidence that vaccination with Hib conjugate vaccine in infancy is associated with risk of diabetes later in life.Diabetes mellitus is believed to occur when genetically susceptible individuals incur pancreatic islet cell damage from viral or other environmental factors. Several investigators have explored the effect of infection on the onset of diabetes. 1–4 Two investigators, Classen and Classen, 5 have hypothesized that receipt of Haemophilus influenzae type b (Hib) conjugate vaccine (HbOC) is associated with an increased risk of type 1 diabetes mellitus (DM) later in life. This possible association has been explored in Finland through a 10-year follow-up study of Finnish children vaccinated in infancy with polyribosylribitol phosphate-D conjugate Hib vaccine as part of an efficacy trial performed in 1985 through 1987 as well as another analysis of an older cohort of children vaccinated at 2 years of age. In those studies there was no evidence that receipt of Hib conjugate vaccine was associated with an increased risk of type 1 DM later in life. 6 Graves et al. 7 found similar results in a case-control study performed in a diabetes study cohort in Colorado.Between 1998 and 1990 the HbOC conjugate Haemophilus influenzae type b conjugate vaccine in infants was evaluated in a large Phase III efficacy trial within Northern California Kaiser Permanente (KP). 8 We report here a 10-year follow-up of this cohort to evaluate the onset of diabetes in recipients and nonrecipients of HbOC.Methods.Between February, 1988, and June, 1990, 76 681 doses of Hib conjugate vaccine (HbOC) were given to 30 400 children 6 weeks to 12–15 months of age within the Northern California Kaiser Permanente Medical Care Program (KP). The HbOC vaccine was administered concomitantly with routine infant and toddler immunizations at ∼2, 4 and 6 months of age with a booster in the second year of life. The vaccine was administered in a partially randomized controlled trial in which children born on certain days of the month were excluded from participation. All other children at the 16 largest of 29 KP medical centers were offered participation. For the purposes of this analysis, the membership records of the children in the original study and their contemporaries at nonparticipating centers were reviewed to identify those children who were still members of KP as of December 31, 2000. Children with DM were identified through review of automated clinical data containing inpatient, emergency and outpatient diagnoses of all children. Rates of diabetes were calculated in vaccinees, in children whose parents refused participation in the trial (refusers) as well as in all children offered participation (acceptors plus refusers), in children randomly excluded from participation by virtue of their birth date (excluded) and in children who were cared for at KP medical centers not participating in the trial (nonparticipants). Statistical comparisons were made among these groups by chi square test.Results.

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