[caption id="attachment_72376" align="alignleft" width="190"] Dr. Schaffner[/caption] William Schaffner, MD Professor of Preventive Medicine, Department of Health Policy Professor of Medicine, Division of Infectious Diseases Vanderbilt University Medical Center Nashville, TN 37203 Dr. Schaffner discusses the recent increase in the incidence of measles infections. MedicalResearch.com: What is the background for this study? Response:  The fundamental reason leading to the increase in measles cases in the US is that some parents are withholding their children from routine measles vaccination: Failure to vaccinate.  As a result, there are neighborhoods, schools, and communities that now have vaccination rates substantially below the 92% to 95% needed to prevent outbreaks of infection.  Measles is the most contagious virus we know, so it takes very high vaccination rates to prevent transmission and to avert outbreaks.  Vaccine hesitancy has many causes:  Lack of knowledge of the severity of measles, concern over vaccine side-effects, low trust in public health, a desire to do things more “naturally” and it can also have political overtones, among others. The measles vaccine is extraordinarily effective; the routine two-dose series confers 97% to 98% protection for life.  The rare “breakthrough” infections that occur in vaccinated persons are generally milder, with fewer complications than in persons who are unvaccinated.  The US was certified as having eliminated measles in 2000 because of high vaccination rates across the country.  Sadly, the US is likely to lose that designation because of sustained measles transmission, reverting us back to the bad old days.  It is particularly sad for any of our children to have to endure measles and its consequences.  All these cases could have been prevented by vaccination. MedicalResearch.com: What roles do a decrease in US immunization rates and/or increased immigration from under-vaccinated area play in this increase?   Response:  The substantial majority of unimmunized children in the US were born and raised in this country.  They usually are members of middle- or upper-income families.  The most frequent importers of measles into the US are our own unimmunized children who travel abroad, encounter measles virus and bring it back to their homes where the virus then spreads among the child’s schoolmates and playmates, creating an outbreak.