Vaccine Benefits, Vaccine Risks: 10 Basic Questions Answered
10. Why are some vaccines given a few times in childhood, and others given every year?
"Before a vaccine is licensed, it is tested to understand how well it can
protect," says Schuchat. "Some vaccines need multiple doses to provide
protection, and some need boosters five or 10 years later to make sure the
protection stays active. Some vaccines given in childhood wear off as a child
becomes a teen, so a new vaccination is needed.
"The vaccine that has to be given every year is the flu vaccine. That has to
be given every year because the flu viruses change quickly. So a totally new
vaccine is made each year."