The Scientific Method

How Vaccines Work

Learn actively by finding out how vaccines work, how vaccines are made, how to visualize risk, and more. Click through these activities to explore the past, present, and future of vaccination and infectious disease.

Herd Immunity

Herd Immunity

See how high vaccination rates protect the unvaccinated. More

Koch’s Postulates

Koch’s Postulates

Learn how scientists identify the cause of an infectious disease. More

Understanding Risk

Understanding Risk

Visualize risks related to vaccination, disease, and other events. More

History of the Immunization Schedule

History of the Immunization Schedule

Find out how the U.S. immunization schedule has changed over time. More

Pioneer Breakthroughs

Pioneer Breakthroughs

Match the scientist to the disease he helped prevent. More

How Vaccines Are Made

How Vaccines Are Made

See the steps involved in manufacturing vaccines. More

Types of Vaccines

Types of Vaccines

Explore the features of attenuated, inactivated, subunit, and conjugate vaccines. More