Prior to the vaccine’s approval, Dr. Margaret Reynolds of the U.S. Rotavirus Efficacy Group presented information on the U.S. pre-licensing clinical trials at the February 12-13, 1997 CDC Advisory Committee on Immunization Practices (ACIP) meeting.
In her presentation, Reynolds reported that in the U.S., clinical trials involved 1,278 infants between five and 25 weeks of age and the infants were randomized to receive a placebo, a monovalent vaccine, or the tetravalent rotavirus vaccine (RotaShield). Infants participating in the study were also permitted to receive other routine vaccines and safety was only studied for five days following administration of each vaccine dose. Fever, diarrhea, and vomiting were noted adverse events following vaccine administration, and four vaccine recipients were hospitalized for these symptoms, with one testing positive for rotavirus. All reactions occurred following administration of dose one or dose two, and primarily on day three or four post vaccination. Many infants who participated in the study also experience a runny nose.
This study reported that the tetravalent rotavirus vaccine had an overall vaccine efficacy against all rotavirus serotypes of 49 percent; however, efficacy rates were reported to be better against severe disease.
Intussusception, a serious condition where a segment of the intestines slides inside another, was noted in the pre-licensing clinical trials and briefly discussed in the FDA review process; however, members of the Vaccines and Related Biological Products Advisory Committee (VRBPAC) chose to ignore the findings and the vaccine was approved for use on August 31, 1998. Additional discussions on intussusception and its association to RotaShield vaccine occurred at the June 1997 and February 1998 ACIP meetings but the panel dismissed any connection.
