Final answer:
Vaccination programs for diseases such as smallpox, polio, and whooping cough create positive externalities because they prevent the spread of diseases to others.
Step-by-step explanation:
Vaccination programs for diseases such as smallpox, polio, and whooping cough create positive externalities. Positive externalities are the benefits that are enjoyed by society as a whole, not just the individual who receives the vaccine. When individuals are vaccinated, they not only protect themselves from the disease but also help to prevent the spread of the disease to others. This is known as herd immunity.