Lay perceptions of the risk and severity of illness have been judged to be moderately low, primarily because the public is thought to be relatively unfamiliar with GBS disease. The potential benefits of the vaccine probably would be perceived as high because of physician cueing. Many women are reluctant to be vaccinated when pregnant, however, so the barriers to vaccination may be high.

Overall, provider perception of the risk of illness is expected to be moderate (the high perception of risk in some areas will be balanced by a very low perception of risk among providers for populations in which the disease is rare). The perceived severity of disease is likely to be high. Even though the predicted efficacy of the vaccine is relatively low, when it is efficacious it will prevent very severe disease; thus, perceived benefits are likely to be high. Liability concerns arising from immunization of pregnant women may act as a barrier to vaccination; these concerns may be somewhat less than those associated with a live preparation. Provider acceptance also may depend, in part, on the availability of alternative strategies such as chemoprophylaxis.

The scope and purpose of the calculations included below are described in Chapters 4 and 7. These calculations are based on certain simplifying procedures and assumptions that have been judged not to compromise their utility for the purposes of this disease comparison. The total costs should be taken only as an approximation of the direct cost of this disease.