There have been no controlled observational studies investigating an association between Hib vaccines and transverse myelitis.

Transverse myelitis has not been reported in any of the controlled clinical trials of plain PRP or PRP conjugate vaccines that have been performed (Barkin et al., 1987; Black et al., 1991b; Campbell et al., 1990; Claesson et al., 1988, 1989; Clements et al., 1990; Dashefsky et al., 1990; Decker et al., 1992; Eskola et al., 1987, 1990a,b; Ferreccio et al., 1991; Frayha et al., 1991; Granoff and Osterholm, 1987; Greenberg et al., 1987; Hendley et al., 1987; Kayhty et al., 1988, 1989; Kovel et al., 1992; Lenoir et al., 1987; Lepow et al., 1984a,b, 1985, 1986, 1987; Peltola et al., 1977; Santosham et al., 1992; Watemberg et al., 1991).

There is no animal model or other data supporting the association between Hib vaccines and transverse myelitis. There are three cases reported in VAERS labeled "transverse myelitis" in children aged 6, 9, and 15 months occurring following the administration of HbOC vaccine during a period when an estimated several million doses of HbOC vaccine were administered. One of these children received HbOC vaccine alone, and the interval between immunization and the development of neurologic symptoms in this child was brief (less than 48 hours). A second child also received DPT and OPV. The patient for whom sufficient documentation of transverse myelitis was provided also had received DPT, OPV, and MMR. No cases of transverse myelitis have been reported following administration of the other Hib vaccines, nor have any cases been reported in the literature.

The evidence is inadequate to accept or reject a causal relation between Hib vaccines and transverse myelitis.

The Guillain-Barré syndrome (GBS) is an acute polyneuropathy that gives rise to muscular weakness, paralysis, and areflexia usually in an as-