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Adverse Events Associated with Childhood Vaccines: Evidence Bearing on Causality
Individuals with a history of immediate hypersensitivity reactions to previous doses of vaccines containing tetanus toxoid may be at increased risk of subsequent reactions. In such individuals, special precautions have been suggested (American Academy of Pediatrics, Committee on Infectious Diseases, 1991; Jacobs et al., 1982; Wassilak and Orenstein, 1988).
A detailed discussion of the evidence regarding death following immunization can be found in Chapter 10. Only the causality argument and conclusions follow. See Chapter 10 for details.
The evidence favors rejection of a causal relation between DPT and sudden infant death syndrome (SIDS) (Institute of Medicine, 1991). Pollock et al. (1984) presented data suggesting that the relative risk of SIDS after DPT versus that after DT is not significantly different from 1. In the committee's judgment the evidence favors rejection of a causal relation between DT and SIDS.
The evidence favors acceptance of a causal relation between DT, Td, and tetanus toxoid and GBS. The evidence establishes a causal relation between DT, Td, and tetanus toxoid and anaphylaxis. Both GBS and anaphylaxis can be fatal. The only well-documented cases of death causally related to immunization with tetanus toxoid, DT, or Td are attributable to anaphylaxis; the evidence regarding death as a consequence of GBS that temporally followed administration of one of these toxoids is very limited. In the committee's judgment DT, Td, or tetanus toxoid may rarely cause fatal GBS or anaphylaxis. There is no evidence or reason to believe that the case fatality rate from vaccine-associated GBS or anaphylaxis would differ from the case fatality rate for these adverse events associated with any other cause.
Reports of death from all other causes are not clearly linked to the preceding immunization. No cases of death were reported by Christensen (1972) in Denmark between 1952 and 1970, a time during which 2.5 million doses of monovalent tetanus toxoid, 2.67 million doses of DT, and 1.1 million doses of Td were given. No cases of death associated with tetanus toxoid, DT, or Td were reported through MSAEFI between 1979 and 1990. During that time, approximately 1.3 million doses of DT and 29 million doses of Td were distributed.