Safety and efficacy of the pentavalent human-bovine (WC3) reassortant rotavirus vaccine in healthy premature infants

Abstract

Background: Premature infants seem to be at greater risk of hospitalization from rotavirus gastroenteritis than term infants. Safety and efficacy of the pentavalent human-bovine (WC3) reassortant rotavirus vaccine were assessed in premature infants enrolled in the large-scale, blinded, placebo-controlled rotavirus efficacy and safety trial (REST).

Methods: Healthy infants 6-12 weeks of chronologic age at study entry were randomized to receive 3 oral doses of pentavalent rotavirus vaccine or placebo at 4- to 10-week intervals. Infants born at < or =36 weeks of gestational age were eligible if thriving at the time of enrollment. Safety and efficacy were retrospectively assessed in these premature infants comparing vaccine with placebo recipients. Cases of rotavirus gastroenteritis were defined as forceful vomiting and/or > or =3 watery or looser-than-normal stools within a 24-hour period, accompanied by detection of rotavirus antigen in the stool.

Results: A total of 2070 infants between 25 and 36 gestational weeks received at least 1 dose of vaccine or placebo; 1005 vaccine recipients and 1061 placebo recipients were evaluable for safety. Serious adverse events occurred in 55 vaccine recipients (5.5%) and 62 placebo recipients (5.8%). In a nested substudy of 308 premature infants evaluable for detailed safety (154 in each group), the frequencies of fever, diarrhea, vomiting, and irritability were comparable between vaccine and placebo recipients. Overall, 3 doses of the pentavalent vaccine reduced the rate of hospitalizations and emergency department visits in premature infants due to rotavirus gastroenteritis by 100% (95% CI: 82.2-100) compared with placebo. The vaccine also prevented 73.0% (95% CI: -2.2-95.2) of rotavirus gastroenteritis cases of any severity.

Conclusions: In this post hoc analysis of healthy premature infants, the pentavalent rotavirus vaccine was generally well-tolerated and substantially reduced rotavirus-attributable hospitalizations and emergency department visits compared with placebo. Overall, vaccine safety and efficacy seemed to be generally comparable to the results in the REST study population as a whole. These results support vaccinating healthy premature infants on the same schedule as term infants.