Imagine that you are responsible for evaluating the potential impact of a $5M grant to scientific research into a vaccine for preventing new syphilis cases. You have the following pieces of information, which you can assume are 100% true for the purpose of this exercise, and you can assume you have all the numbers you need. What is the social ROI of the grant? Your answer should be in terms of a multiple of the cost of the grant (e.g. if the social return was $500M, the ROI would be 100x).

• Total number of new syphilis cases per year: 6M

• Lost DALYs [disability adjusted life years] per new case of syphilis: 1

• Years until new vaccine if this grant fails: 20

• Years until new vaccine if this grant succeeds: 17

• Chance of grant succeeding: 5%

• New syphilis cases prevented by vaccine once released: 30%

• Value per DALY: $50,000