Q: Can a vaccinated child bring home the measles virus if he encounters an infected child in day care?
A: It is highly unlikely, according to Dr. William Schaffner, an infectious diseases expert at the Vanderbilt University School of Medicine. Someone who is immune cannot spread the disease. A toddler who has received one shot has a 95 percent chance of being immune. With two shots, the likelihood of immunity rises to 97 percent. In both cases the chance of a vaccine failure -- in which case a vaccinated toddler could become infected and transmit measles -- is very small.
Assuming the vaccine is effective, as it is in most cases, Schaffner said, vaccinated children, "even if they are exposed to the measles virus, cannot then transmit the virus to others. That's because the vaccinated child's antibodies completely surround, attach to and then kill the virus.
"The measles virus can't multiply in the vaccinated child, and the vaccinated child cannot be an agent of transmission to others. That's why vaccinated children protect the unvaccinated."
Q: Should a man born in 1958 who never had measles or the vaccine be vaccinated now?
A: It is best to check with a doctor, but the answer is likely to be yes, unless you have a medical condition that would make the vaccine risky for you. If you are planning international travel, the answer will certainly be yes. Worldwide there are still 20 million measles cases a year. And adults can be hit hard by the measles and are at risk of pneumonia from it. The virus weakens the immune system and makes people more prone to bacterial types of pneumonia.
Q: Regarding measles, what if you are an older person who doesn't have a record of what vaccinations or childhood infections you had? Is there a test or something that can verify your immunity status?
A: Everyone born before 1957 is assumed to be immune to measles, because virtually everybody caught it and became immune before the vaccine became available in 1963. It is possible to have a blood test to look for antibodies, which will tell whether you are immune; if you aren't, you can get the shot. However, it is cheaper, easier and faster to just get the shot. Even if you were vaccinated or did have measles, there is no harm in being vaccinated again.
In addition, some people who were vaccinated between 1963 and 1967 may have inadequate protection because they received a killed measles virus vaccine, rather than the more effective attenuated live virus vaccine, said Michael Sennett of the National Center for Immunization and Respiratory Diseases at the Centers for Disease Control and Prevention. An estimated 600,000 to 900,000 people received the killed vaccine, compared with more than 400 million doses of live vaccine that have been administered since the vaccine was licensed, he said.
Those who received the inactivated measles vaccine, or are unsure which type they received, should be considered unvaccinated and be revaccinated if they don't have other evidence of immunity. If there are concerns about an individual's vaccination history, it is prudent to be revaccinated, Sennett said.
ActiveStyle on 02/23/2015