FALLS CHURCH, Va. - The United States is currently experiencing the highest number of measles cases since 1994. Here are answers to some of the more frequently asked questions about measles in the Department of Defense:
Why is a "3rd dose of MMR" recommended during mumps outbreaks, but not during measles outbreaks?
MMR vaccines are highly effective at providing lifetime protection against measles. In contrast, MMR vaccines are less consistently effective against mumps, and mumps immunity may wane over time. CDC/ACIP therefore recommend extra MMR vaccination during mumps outbreaks, at the discretion of public health authorities who define the time and location parameters of a mumps outbreak. When extra MMR doses are recommended, CDC/ACIP advise that no one should receive more than three lifetime doses.
What is "documentation of adequate vaccination" against measles?
Written documentation of vaccination includes vaccine type, date, administration details, and clinic stamp; documentation may be in a medical record of an official immunization record (e.g., "yellow shot card"). Children should have two documented doses of MMR (or MMRV) administered after age 12 months and separated by at least 28 days. Adults should have at least one documented lifetime dose of a live-measles vaccine (like MMR or MMRV). Adults should have two documented lifetime doses of live-measles vaccine if they are international travelers, students, healthcare workers, household contacts of immune-compromised people, or otherwise considered at higher risk of measles exposure.
What is "laboratory evidence of immunity" against measles?
When people cannot provide documentation of adequate vaccination against measles, a blood test may demonstrate the presence of measles antibodies in sera. This serologic test is often called a "titer" test. If any serologic test in a person’s life ever demonstrates measles antibodies, CDC/ACIP consider this evidence of measles immunity.
Should people get extra serologic testing for immunity because of measles outbreaks?
No. After evidence of measles immunity has been established by either documented vaccination or laboratory testing, serologic testing should not be performed. If serologic testing is performed after evidence of immunity has been established, results of serologic testing should be ignored. CDC/ACIP make this recommendation because, after measles immunity has been established, it is possible for measles antibodies to become undetectable in sera even though immunity is maintained. In these cases, an immune anamnestic (memory) response should occur after actual viral exposure and the person will still be protected from measles.