To provide another chance to develop measles immunity for persons who did not respond to the first dose.
The second dose is to provide another chance to develop measles immunity for persons who did not respond to the first dose. The second dose of MMR may be given as early as a month after the first dose, and be counted as a valid dose if both doses were given after the first birthday. The Advisory Committee on Immunization Practices (ACIP) recommends a two-dose vaccine schedule for measles, mumps, rubella and varicella vaccines for children, with the first dose at age 12-15 months and the second at age 4-6 years. The second dose of MMR may be given as early as 4 weeks after the first dose, and be counted as a valid dose if both doses were given after the first birthday. The second dose is not a booster, but rather it is intended to produce immunity in the small number of people who fail to respond to the first dose. MMR vaccine is recommended routinely for all children at age 12 through 15 months, with a second dose at age 4 through 6 years. The second dose of MMR can be given as early as 4 weeks (28 days) after the first dose and be counted as a valid dose if both doses were given after the child's first birthday. A dose of MMR vaccine is usually given to children aged 12-13 months. A second dose is usually given as a preschool booster. The MMR vaccine is very safe and is not linked with autism or bowel diseases. MMR stands for measles, mumps and rubella. Children can get the second dose earlier, as long as it is at least 28 days after the first dose. Students at post-high school educational institutions without evidence of immunity against measles need two doses of MMR vaccine, with the second dose administered no earlier than Why is a second dose of MMR necessary? About 2%-5% of persons do not develop measles immunity after the first dose of vaccine. This occurs for a variety of reasons. The second dose is to provide another chance to develop measles immunity for persons who did not respond to the first dose.
http://www.autism-pdd.net/testdump/test9163.htm http://www.cdc.gov/vaccines/vpd-vac/combo-vaccines/mmrv/vacopt-faqs-hcp.htm http://www.immunize.org/askexperts/experts_mmr.asp http://www.immunize.org/askexperts/experts_mmr.asp http://patient.info/health/mmr-immunisation http://www.cdc.gov/vaccines/vpd-vac/measles/vacc-in-short.htm http://www.mothering.com/forum/47-vaccinations/443139-mmr-second-dose-not-booster.html
why is a second dose of mmr necessary