Effect of dose and a comparison of measures of vaccine take for oral rhesus rotavirus vaccine

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Abstract
Ninety-six healthy infants ages 2 to 5 months received rhesus rotavirus vaccine serotype 3 (RRV) as a single dose of 103, 104 or 105 plaque-forming units (pfu) in this double-blinded, placebo-controlled study. Half of the infants in each dose group were also randomized to receive either 30 ml of infant formula as buffer before vaccination or were vaccinated on an empty stomach. The incidence of fever, increased stool frequency and decreased activity level was consistently higher among infants who received RRV than those who received placebo. There was no consistent increase in incidence of symptoms as the dose of RRV was increased. Possible vaccine-related side effects were increased in older vaccinees and in those with higher prevaccination antibody titers. The serocon version rate and pre to postvaccination antibody rise, evaluated by enzyme-linked immunosorbent assay and by plaque reduction neutralization, correlated well. The 105 and 104 pfu RRV dose produced significantly higher rates of seroconversion and higher antibody rises than did placebo (P < 0.001 for 105 and P = 0.005 for 104). The 103 pfu dose was no more immunogenic than placebo. In the 104 pfu dose group 73% of infants receiving formula as a “buffer” seroconverted compared with 36% of those not receiving formula; 63% of infants partially breast-fed or formula-fed seroconverted compared with 17% of those exclusively breast-fed. These differences in seroconversion rate were largely overcome by increasing the RRV dose to 105 pfu. Stool (copro IgA) antibody responses were examined; of six infants showing a copro IgA response only