FDA Panel Fails To Back PMC's TriHIBit Vaccine

The US Food and Drug Administration's Vaccines and Related BiologicsAdvisory Committee has said it does not have enough data to decide whether to recommend approval of Pasteur Merieux Connaught's TriHIBit vaccine against Hemophilus influenzae type B, diphtheria, tetanus and pertussis for more widespread pediatric use.

In a split decision, the panel noted there was insufficient evidence to support that the combination acted similarly to its component parts. TriHIBit was approved as a fourth booster dose in children aged 15-18 months in September 1996.

The panel's concerns seem to rest with the immunogenicity of the Hib portion of the vaccine when given in combination. Panel chairwoman Patricia Ferrieri of the University of Minnesota noted that, given the public health need for a combination vaccine, the FDA and PMC ought to deal with the committee's concerns as quickly as possible. Thomas Fleming of the University of Washington said there was clearly some evidence of interference when Hib antibody levels were assessed, and other concerns were raised over the methodology of the trials and the analysis used to evaluate the vaccine.