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A preventive approach is thus desirable; it also appears to be practicable because an opportunity exists to deliver a vaccine prior to the period of maximum exposure. The growing problem of antibiotic resistant organisms would be obviated by a vaccine.

Success of a vaccination prevention approach is dependent upon development of a suitably protective vaccine. It also may require efforts to change misconceptions about the risk and consequences of the disease, particularly among lay persons.

Vaccine Preventable Illness

Defining the target population is the first step in calculating the possible reduction in morbidity and mortality that could be produced by a vaccine candidate. This knowledge can be translated into an estimate for vaccine preventable illness (VPI). VPI is defined as the number of cases, complications, sequelae, and deaths that could be prevented by immunization of the entire target population with a hypothetical vaccine that is 100 percent effective.

In calculating the benefits that could result from a gonococcal vaccine, it is assumed that all disease occurring over 15 years of age and all fetal deaths due to ectopic pregnancy are potentially vaccine preventable. None of the disease occurring in the 5–14 years age group is considered vaccine preventable, because children under 15 years of age are not included in the target population. Table L.5 presents a summary of VPI for gonorrhea.

Vaccine Preventable Illness Values

The concept of “infant mortality equivalence value” is used to standardize vaccine preventable illness scores, just as it is used to standardize disease burden values (see Chapter 4). Vaccine preventable illness values for gonorrhea are calculated using estimates from Table L.5 and the two sets of IME values employed throughout this report. Using IME values based on a median of committee member perspectives, the vaccine preventable illness value for gonorrhea is 527; with the age-neutral perspective the value is 13,811. If the IME value for first trimester fetal deaths in the age-neutral perspective were changed from 1 to 100 (as it is in the committee median perspective), the age-neutral VPI value would become 347.

Possible Reduction in Morbidity and Mortality (PRMM)

Calculation of the possible reduction in morbidity and mortality (or maximum potential health benefit) that could be achieved with a gonorrhea vaccine is somewhat different than the operation as performed for other vaccines, because in this case the candidate is “one of several promising options” rather than a specific vaccine. The committee believes, however, that a gonorrhea vaccine could achieve licensure

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