When COVID struck, many turned to the film Contagion for insight. In one scene, Kate Winslet’s character explains how pathogens spread via everyday objects like “door knobs, water fountains, elevator buttons and each other.” Diseases are measured by R0, indicating how many people one infected person can pass the illness to. Measles tops the list with an R0 of 12–18, making it extremely contagious—even lingering in a room hours after exposure. Other fast-spreading diseases include pertussis, chickenpox, and COVID. TB, Ebola, and MERS spread more slowly but remain dangerous. Vaccination and herd immunity are key to protecting vulnerable populations.
How Contagious Is Too Contagious? Science Reveals the Most Infectious Diseases on Earth
