A87 (≥50yrs), herpes zoster (≥50yrs), and pertussis (≥18yrs) made up 51%, 30%, 16%, and 3% of the cost, respectively. Among those aged ≥50 years, influenza, pneumococcal disease, herpes zoster, and pertussis made up 31%, 44%, 24%, and 1% of the cost, respectively. Most (82%) pneumococcal costs stemmed from nonbacteremic pneumococcal pneumonia (NPP). Direct medical costs accounted for 91% of total pneumococcal burden, but only 27%, 28%, and 42% of total economic burden due to influenza, herpese zoster, and pertussis, respectively. Sensitivity analysis revealed that estimated influenza rates and costs per case, NPP incidence and directs costs, and herpes zoster incidence rates and indirect costs impacted the model most. CONCLUSIONS: Cost attributable to adult VPD in the United States is substantial. Broadening adult immunization efforts beyond influenza only may help reduce the economic burden of adult VPD, and a pneumococcal vaccination effort, primarily focused on reducing NPP, may be a logical place to start.