Measles is a highly contagious virus. There are measles outbreaks in the United States and Canada. Two doses of the MMR vaccine provide the best protection against infection and illness.
"Community immunity" means people are protected from a disease because of a vaccine (vaccine-induced immunity) or prior infection (infection-induced immunity). Community immunity helps protect the whole group, even people who didn’t get a vaccine or who have not been sick before. Think of this like a wall made of bricks. Each brick is a person who is protected from an infectious disease. The more bricks (people) there are, the stronger the wall (protection) is to keep the disease out.
Changed