Is vaccine development responsive to population disease burden?

Introduction: The majority of notifiable infectious diseases in the United States are not targets of currently licensed vaccines. We examined whether recent vaccine development reflects disease burden in the US population. Methods: We identified notifiable diseases with the highest US annual incidence but no US-licensed vaccines during the period 1996-2000 (chlamydia, gonorrhea, HIV-AIDS, salmonellosis, syphilis, shigellosis, tuberculosis, E. coli-related enteritis, hepatitis C). For each disease, we used published sources to determine 3 measures of burden: mean annual incidence, case-fatality rate, and annual attributable deaths. Using a proprietary global database of pharmaceutical development for the years 2000-2010, we calculated the number of “vaccine-years” of development, summing years of development across all vaccine candidates for each target disease. Values for burden and development were not normally distributed, so we conducted nonparametric tests (Spearman correlations) to assess statistical significance of relationships. Results: Mean annual incidence ranged from 3,472 (hepatitis C) to 597,758 (chlamydia). Case-fatality rates ranged from .001% (chlamydia, gonorrhea) to 31% (HIV-AIDS). Mean annual deaths ranged from 3 (gonorrhea) to 12,543 (HIV-AIDS). Vaccine development ranged from 0 (syphilis) to 297 (HIV-AIDS) “vaccine-years.” Case-fatality rate and vaccine development were significantly associated (rho=.72; p=.03). In contrast, disease incidence and attributable deaths were not associated with vaccine development. Conclusions: Recent prophylactic vaccine development is associated with case-fatality rate but not annual deaths or incidence of common notifiable diseases. To encourage vaccine development for diseases with comparatively low case-fatality rates, public health and research communities may need to provide targeted incentives.