Posted on February 11, 2015 One of the fundamental errors in thinking about measles vaccine effectiveness is that receipt of measles-mumps-rubella (MMR) vaccine equates to bona fide immunity against these pathogens. Indeed, it is commonly claimed that receiving two doses of the MMR vaccine is “99 percent effective in preventing measles,”1 despite a voluminous body of contradictory evidence from epidemiology and clinical experience. This erroneous thinking has led the public, media and government alike to attribute the origin of measles outbreaks, such as the one recently reported at Disney, to the non-vaccinated, even though 18% of the measles cases were in those who had been vaccinated. (hardly “99% effective) The vaccine has obvious fallibility indicated by the fact that they now requires two doses. The problems with the failing MMR vaccine go much deeper, and can carry profound health risks (over 25 of which have indexed here: MMR vaccine dangers). Reports of an increased risk for autism, which a senior CDC scientist confessed his agency covered up. The MMR vaccine failure to consistently confer immunity, and those who have been “immunized” with two doses of MMR vaccine can still transmit the infection to others, a phenomena no one is reporting in the rush to blame the non- or minimally-vaccinated for the outbreak. MMR Vaccinated Can Still Spread Measles Last year, a groundbreaking study published in the journal Clinical Infectious Diseases , whose authorship includes scientists working for the Bureau of Immunization, New York City Department of Health and Mental Hygiene, and the National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention (CDC), Atlanta, GA, looked at evidence from the 2011 New York measles outbreak that individuals with prior evidence of measles vaccination and vaccine immunity were both capable of being infected with measles and infecting others with it (secondary transmission). This finding even aroused the attention of mainstream news reporting, such as this Sciencemag.org article from April 2014 titled “ Measles Outbreak Traced to Fully Vaccinated Patient for First Time .” So did you follow that? A twice-vaccinated individual, from a NYC measles outbreak, was found to have transmitted measles to four of her contacts, two of which themselves had received two doses of MMR vaccine and had prior presumably protective measles IgG antibody results. Stop Blaming A Failing Vaccine on Failure to Vaccinate The moral of the story is that you can’t blame non-vaccinating parents for the morbidity and mortality of infectious diseases when vaccination does not result in immunity and does not keep those who are vaccinated from infecting others.