Age of Administration and Safety of Measles-Containing Vaccines

October 25, 2013

Age of Administration and Safety of Measles-Containing Vaccines

  1. Robert S. Baltimore, MD

The risk for postimmunization seizures and fever was significantly greater among children aged 16 to 18 months than among those aged 12 to 15 months.

  1. Robert S. Baltimore, MD

Measles (M)-containing vaccines, when administered to children aged 12 to 23 months, are associated with increased risk for fever and febrile seizures 1 to 2 weeks after immunization. In the U.S., the only M-containing vaccines are measles, mumps, and rubella (MMR) and measles, mumps, rubella, and varicella (MMRV); the first dose is administered at 12 to 15 months, and the second at 4 to 6 years. The risk for febrile seizures 1 to 2 weeks following immunization is twice as high with MMRV as with separately administered MMR and V preparations. Between ages 12 and 23 months, the background rate of febrile seizures peaks at 16 to 18 months.

To determine the risk for fever and seizures following immunization with M-containing vaccines at various ages, researchers analyzed data from the Vaccine Safety Datalink (VSD) — a collaborative effort between the CDC and 10 managed-care organizations. The analysis involved records for 840,348 children who had received M-containing vaccine at ages 12 to 23 months between 2001 and 2011.

A total of 18,403 fever episodes and 1810 seizure events occurred during the 42 days postvaccination. The relative risk for fever and seizures 7 to 10 days postvaccination (the time of greatest risk) was significantly higher in children aged 16 to 23 months than in those aged 12 to 15 months. When the 7- to 10-day risk interval was compared with a control interval, the attributable risk for seizures — but not fever — during the risk interval was significantly greater in the older group.


Age at time of vaccination is currently being debated among a minority of vaccinators who suggest “alternative” schedules. Some physicians and their followers recommend separating the measles, mumps, and rubella components and raising the age of MMR vaccination, proposing that this will minimize vaccine-related hazards, but they lack supporting data. This study provides strong support for the current American Academy of Pediatrics/Centers for Disease Control and Prevention recommendations.

Editor Disclosures at Time of Publication

  • Disclosures for Robert S. Baltimore, MD at time of publication Editorial boards Current Opinion in Pediatrics; Infectious Diseases in Children


Reader Comments (1)

CHRISTI HILL Other Healthcare Professional, Pediatrics/Adolescent Medicine, Public schools

There's only one problem with the measles vaccination being given at 12months-- since it is often combined with rubella vaccine-- is that neither produces adult immunity. My daughter received MMR on her first birthday; 27 years later, her OB found that she had NO immunity.
I'm part of the generation that suffered through all of the "childhood " illnesses. I continue to be immune after 60 years!
This does not mean that I would want today's kids to endure the illesses.....


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