Post-licensure comparative study of unusual high-pitched crying and prolonged crying following COMVAX™ and placebo versus PedvaxHIB™ and RECOMBIVAX HB™ in healthy infants

Background: In a previous clinical trial comparing COMVAX™ with its monovalent components, PedvaxHIB™ and RECOMBIVAX HB™, one of 92 comparisons of post-vaccination adverse experiences revealed a higher rate of unusual, high-pitched crying following the second, but not the first or third doses of COMVAX™ compared with two monovalent control vaccines. Rates of prolonged crying were similar between groups at each visit. Objectives: To compare the frequencies of unusual, high-pitched crying between recipients of COMVAX™ plus placebo and recipients of PedvaxHIB™ plus RECOMBIVAX HB™ following the second vaccine doses (primary) and to summarize the frequency of unusual, high-pitched crying and prolonged crying after each vaccination visit. Design: We enrolled 1215 healthy infants in a randomized, double blind, placebo-controlled study. Participating infants received study vaccines at 2 and 4 months of age and other routine childhood vaccines at 6–7 weeks and 3 months of age. Crying was evaluated via questionnaire at the time of enrollment (baseline) and daily from days 0 to 2 after each injection. Results: Reports of unusual, high-pitched crying and prolonged crying were uncommon (