The following Questions and Answers are from Immunization Action Coalition.

Measles is caused by a virus.

Measles is spread from person to person through the air by infectious droplets; it is highly contagious.

It takes an average of 10–12 days from exposure to the first symptom, which is usually fever. The measles rash doesn’t usually appear until approximately 14 days after exposure, 2–3 days after the fever begins.