February 16, 2015 – Humans Only

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Anchor lead:  Much of the spread of measles has to do with how very infectious it is, Elizabeth Tracey reports

CDC reports continue to sound the alarm that measles is spreading around the country, belying the assertion made a few years ago that declared measles eradicated in the United States.  Diane Griffin, a measles expert at Johns Hopkins, says one characteristic of the measles infection accounts for much of this reemergence.

Griffin: We need a very high coverage.  We need a higher coverage than we needed for smallpox or even for polio.  We need more than 95% of people to be immune because the virus is so infectious that it will find those one or two people that are not immune.  Delivering the vaccine is key to controlling the disease.  We need two doses of the vaccine and that’s mainly because not everyone responds the first time and those people need a second chance.   :30

Griffin says waning immunity, where people once more become susceptible to becoming infected in spite of having been vaccinated, also plays a role and suggests that boosters may be appropriate.  At Johns Hopkins,  I’m Elizabeth Tracey.