Understanding the molecular basis for the risk of aseptic meningitis after immunization with the Urabe mumps strain (compared to the experience with the Jeryl Lynn strain) might lead to better understanding of the pathogenetic capacity of mumps virus and to principles of viral pathogenesis that would aid in the development of safe attenuated virus vaccines in the future.

Insulin-dependent diabetes mellitus (IDDM) is a serious and relatively common disorder. The large number of reports raising the suspicion that mumps vaccine might induce the onset of IDDM suggests the need for systematic study of the question.

There is a need to understand the basis for reversion of oral polio vaccine to a more virulent form to prevent its occurrence.

Evidence is inadequate to accept or reject a causal relation between hepatitis B vaccine and Guillain-Barré syndrome, transverse myelitis, optic neuritis, multiple sclerosis, or other demyelinating syndromes. The absence of reports of such outcomes in large-scale field trials suggests that if hepatitis B vaccine causes these adverse events, it does so at a very low frequency. Nevertheless, the number of reports questioning the relation between hepatitis B vaccine to one or the other of these disorders of similar character suggests the need for systematic research.

The possibility that hepatitis B vaccine can cause an exacerbation of rheumatoid arthritis should be carefully evaluated in a population-based study.

The committee found that the evidence favors acceptance of a causal relation between tetanus toxoid and Guillain-Barré syndrome (GBS) and between oral polio vaccine and GBS. For the other vaccines, the association with GBS is inconclusive, and research is needed to clarify the association. The following information is potentially obtainable through research: (1) the background incidence of GBS in the U.S. by year of life in the pediatric age group, particularly in infants and preschool-age children; (2) the incidence of GBS after the receipt of each vaccine and combination of vaccines administered to children or adults; and (3) more precise knowledge