Fig. 2.

A balanced vaccine product portfolio as a risk assessment tool. A representative of vaccine products portfolio shows that products can be classified into 4 main categories: 1. Large potential return, high feasibility (top right quadrant/orange): 2. Small potential return, high feasibility (top left quadrant/yellow); 3. Large market opportunity, low feasibility (bottom right quadrant/yellow); 4. Small market opportunity, low feasibility (bottom left quadrant/grey), where X-axis represents potential financial returns, and Y-axis represents the degree of feasibility of vaccine development. This figure is a courtesy of J. Chu.