Rotavirus is the most serious cause of diarrheal illness in infants six to 24 months of age and is responsible for more than 54,000 hospital admissions and up to 40 infant deaths annually in the United States. The National Institutes of Health developed an oral tetravalent rotavirus vaccine (RV-TV) against the four human serotypes responsible for most rotaviral disease. Markwick and associates evaluated RV-TV coadministered with oral poliovirus vaccine (OPV) and a combined diphtheria-tetanus-pertussis and Haemophilus influenzae type b vaccine (DTP/Hib) in healthy infants to see if it would significantly diminish the immunogenicity of the other vaccines.
Healthy infants between six and 12 weeks of age were eligible for this multicenter trial. Exclusion criteria included previous administration of OPV, DTP or Hib, residence in a household with an immunosuppressed person and active participation in another clinical trial. Infants were randomized to receive either three doses of RV-TV or a placebo concurrently with their regularly scheduled DTP/Hib and OPV vaccines at approximately two, four and six months of age. The safety of the RV-TV vaccine was documented in two ways. First, the infant's caregiver recorded the infant's temperature, any respiratory or gastrointestinal symptoms, and activity level on a diary card for five days following the vaccination. Second, the caregiver was interviewed at each visit to determine whether any adverse events occurred following the previous vaccination. In addition, blood samples were obtained at baseline and three to six weeks after the third dose of vaccines.
A total of 267 infants were enrolled in the study; 133 were randomized into the RV-TV group and 134 were randomized into the control group. Demographic characteristics were similar between groups. Eighty-five percent of the infants receiving RV-TV seroconverted as measured by antirotaviral IgA antibodies. The percentage of infants who attained protective antibody titers against H. influenzae type b, diphtheria toxoid and tetanus toxoid did not differ between the two groups. The incidence of most side effects did not differ significantly between groups; however, infants in the RV-TV group experienced more wheezing, decreased appetite, and decreased activity than did patients in the placebo group, but these events were not considered clinically significant.
The authors conclude that RV-TV could easily be incorporated into the routine well-child schedule and can be safely coadministered with three doses of DTP/Hib and OPV without diminishing an infant's serum antibody response to these vaccines.