Question: What is the problem with infants and why do children need so many vaccines?

Sarah Burl answered on 18 Jun 2010:

Because they have an immature immune system and so can’t respond to the vaccine well. Several vaccines have to be given boosters to get a good long term response. The best vaccines are called live vaccines and they have a small part of the infection in the vaccine but does not make you sick, the vacines that don’t have this are called killed vaccines and are not as good and so need more boosters to get a good response.