Evidence for Association

Biologic Plausibility

A general discussion of transverse myelitis and vaccination can be found in Chapter 3. There are no data specifically bearing on the biologic plausibility of a causal relation between Hib vaccines and transverse myelitis.

Case Reports, Case Series, and Uncontrolled Observational Studies

There have been three cases reported in VAERS (submitted between November 1990 and July 1992) labeled as "transverse myelitis" following Hib vaccination. HbOC vaccine was the Hib vaccine used in all three cases. In one patient (there appeared to be two reports of this one case), the HbOC vaccine was administered alone, in the second the HbOC vaccine was administered with DPT and oral polio vaccine (OPV), and in the third HbOC vaccine was administered with DPT, OPV, and MMR. Only the third case provided sufficient evidence to establish a diagnosis of transverse myelitis. This child developed transverse myelitis 14 days after immunization with the HbOC, DPT, OPV, and MMR. She had a diffuse rash, diarrhea, and a fever 10 days after vaccination and 4 days prior to the onset of transverse myelitis. This case report was the only one to provide information on follow-up. At 4.5 months following vaccination, a magnetic resonance image (MRI) of the thoracic spine showed extensive atrophic change of the thoracic cord, extending from the seventh thoracic vertebra (T-7) through T-12. At 10 months postvaccination there was "persistent transverse myelitis" at the T-8 through T-10 level.

Insufficient data were provided for the other two cases to determine whether the children actually had transverse myelitis. One of these children developed a temperature of 40.6ºC (105ºF) and "extreme floppiness and toxic appearance" 24 to 36 hours after immunization with the HbOC vaccine alone. He had a "multitude of lab tests and MRI" and was hospitalized for 30 days. The other baby was noted to be unable to crawl 12 days after immunization with the HbOC vaccine, DPT, and OPV. The mother reported that a neurologist felt that this child had possible transverse myelitis from polio vaccine. She reported that the lumbar puncture and brain scan were normal. The child was hospitalized for 2 days, and no further follow-up information was provided.

There have been no cases of transverse myelitis reported in any case series or uncontrolled observational studies of Hib vaccines (Ahonkhai et al., 1990, 1991; Black et al., 1987; Claesson et al., 1991; Fritzell and Plotkin, 1992; Milstien et al., 1987; Parke et al., 1991; Popejoy et al., 1989; Rowe et al., 1990; Santosham et al., 1991a; Vadheim et al., 1990).

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