In the race for a vaccine, we must go big. Really big.

An advance market commitment for Covid-19 should combine “push” and “pull” incentives. The “pull” incentive is the commitment to buy 300 million courses of vaccine at a per-person price of $100, for vaccines produced within a specified time frame. If multiple vaccines are developed, the A.M.C. fund will have authority to choose products to purchase based on efficacy, the availability of sufficient vaccine for timely vaccination or suitability for different population groups. So firms compete to serve the first 300 million people with the most attractive vaccines, and the “pull” component provides strong incentives for both speed and quality.

The “push” incentive guarantees firms partial reimbursement for production capacity built or repurposed at risk and partial reimbursement as they achieve milestones. The partial reimbursement ensures that manufacturers have “skin in the game,” while inducing them to build large-scale capacity before approval is certain.

The A.M.C. is a win-win solution: It reduces the risk to firms from building production capacity or repurposing it from other uses before vaccine testing is complete, while focusing investment on products that firms believe could potentially meet the technical specifications of the vaccine. This ensures that the entrepreneurs who have the most information and expertise and are best placed to make judgments about whether a vaccine is sufficiently promising to merit large-scale investment will have a voice in decisions and skin in the game.