a manufacturer, with a 5 representing highest likelihood and 1 representing least likelihood.
Using each attribute’s measure (Xi for the ith attribute), a utility scale, Ui(xi), is formed so that the least desired (worst) level (Xi=xi0) is scaled as Ui(xi0)=0 and the most desired (best) level for that attribute (Xi=xi1) is scaled as Ui(xi1)=100. In SMART Vaccines the intermediate levels of Xi are scaled linearly relative to these two endpoints.
Each vaccine to be prioritized, V, may be considered as a vector of attributes, V=(x1, x2, …, xn), where each component of the vector indicates the expected performance of that vaccine on the measure for the particular attribute. This is rescaled into a vector of single attribute utility scales, Vj=(U1(x1j), …, Un(xnj)), to represent the vaccine as input to the multi-attribute utility scoring algorithm.
Finally a set of weights, wi, i=1…n, is specified to represent the relative value from 0 to 100 for each attribute in relation to the others. The weights are then normalized so that their sum is equal to 100, which allows each weight to be interpreted as a percentage of the total weight. The final scoring function is the weighted sum represented as
where U(Vj) is the utility score for the vaccine Vj. By scaling the worst and the best levels of each attribute between 0 and 100 and by normalizing the sum of the wi’s to be 1, this score will also range between 0 and 100. In SMART Vaccines this resulting score is labeled the “SMART Score.” Vaccines are ranked in priority according to the rank order of their SMART Scores. Figure 2-1 shows a diagram of the SMART Vaccines framework, slightly revised from the 2012 IOM report. Appendix A details the computational model supporting SMART Vaccines.
In the 2012 report, the committee organized 29 stakeholder-informed attributes into eight categories. Following the Phase II deliberations, the committee slightly revised this listing (see Table S-1). In SMART Vaccines 1.0, a choice of 28 attributes spread across eight categories is available to users, with an option of adding up to seven user-defined attributes in a ninth category.
One attribute, the likelihood of successful licensure within the next 10 years, was removed from the original list and instead incorporated as a vaccine characteristic because this attribute works as a multiplier on the overall SMART Score. In the extreme, if there is no chance of licensure, then it does not matter how good the vaccine scores on other attributes—