using search strategies most appropriate for each. The exact choice of terms depended on the particular data base, but all terms related to the concepts of vaccines and adverse effects. For example, ''whooping cough" might have been used instead of (or in addition to) "pertussis," or "reactions" might have been used instead of (or in addition to) "adverse effects."
To further ensure inclusion of relevant material, the two medical files (Medline and EMBase) were searched using combinations of the vaccine terms with various specific medical terms or conditions. For pertussis vaccine, these terms were anemia, hemolytic; spasms, infantile; Reye syndrome; peripheral nerve disease; sudden infant death; meningitis, aseptic; diabetes mellitus; autism; learning disorders or dyslexia; hyperkinesis; brain; convulsions; encephalitis; and epilepsy. For rubella vaccine, the specific terms used were polyradiculoneuritis and arthritis.
Searches were later conducted for the adverse events added to the committee's charge after the project was under way. For pertussis vaccine, the added adverse events were anaphylaxis; erythema multiforme or other rash; Guillain-Barrè syndrome, including mononeuropathy and polyneuropathy; protracted inconsolable crying or screaming; thrombocytopenia; and shock or "unusual shock-like state" with hypotonicity, hyporesponsiveness, and short-lived convulsions, usually febrile. For rubella vaccine, the additional adverse event was thrombocytopenic purpura. These searches were conducted in a manner similar to those described above.1
For the searches in the two medical data bases, where the structure of the data base makes it possible, items found were sorted according to whether they dealt with human or animal subjects. Review articles were also noted.
As lists of citations were generated by computer literature searches, staff, committee members, or both examined them and ordered abstracts of any that concerned the issues or conditions being examined by the committee. Upon receiving the abstracts, a further determination was made by staff and committee as to whether a particular article might contain information pertinent to the committee's task. Articles were then obtained for each selected abstract, and copies were distributed to the appropriate committee members.
Other sources of information were used by the committee. These included reference lists; presentations to the committee at its public meeting,
1 A more detailed document entitled "Searches of Electronic Data Bases: Adverse Events Following Pertussis and Rubella Vacination" is available from the National Technical Information Service, 5285 Port Royal Road, Springfield, Virginia 22161 (703-487-4650). Resumès of the librarian who carried out the searches and of the manager of the National Research Council Library are included.