In the medical journal Vaccine,2 Dr. Gregory Poland, the journal’s editor-in-chief, professor of medicine and founder and leader of Mayo Clinic’s Vaccine Research Group, recently made surprising public statements about the poor effectiveness of measles vaccine in the MMR shot.
For many years, Dr. Poland has been a strong mandatory vaccination proponent and has criticized MMR vaccine safety critics but now he is taking the lead in publicly criticizing the vaccine’s failure to prevent measles.
Public health agencies have been reporting measles outbreaks in the US for the past few years, which they often blame on unvaccinated individuals, despite the fact that in 2012, 95 percent of children entering kindergarten had gotten two MMR shots and so had more than 90 percent of high school students.
With this high degree of compliance with a supposedly effective measles vaccine, many people have been wondering why the U.S. is seeing a resurgence of measles cases (from January 1 to June 6, 2014, the CDC reported 397 cases of measles and 16 outbreaks in the US).3
For starters, it’s important to remember that, like B. pertussis whooping cough and other infectious diseases, measles has natural cyclical increases and decreases every few years in populations.
These may occur even in highly vaccinated populations because the vaccine itself is not a guarantee of long lasting immunity and even two doses of MMR vaccine can fail to protect. According to Dr. Poland, who is conducting research at Mayo Clinic to develop new measles, mumps and rubella vaccines:4
“…the immune response to measles vaccine varies substantially in actual field use. Multiple studies demonstrate that 2–10% of those immunized with two doses of measles vaccine fail to develop protective antibody levels, and that immunity can wane over time and result in infection (so-called secondary vaccine failure) when the individual is exposed to measles.
For example, during the 1989–1991 U.S. measles outbreaks 20–40% of the individuals affected had been previously immunized with one to two doses of vaccine. In an October 2011 outbreak in Canada, over 50% of the 98 individuals had received two doses of measles vaccine… this phenomenon continues to play a role in measles outbreaks.
Thus, measles outbreaks also occur even among highly vaccinated populations because of primary and secondary vaccine failure, which results in gradually larger pools of susceptible persons and outbreaks once measles is introduced.
This leads to a paradoxical situation whereby measles in highly immunized societies occurs primarily among those previously immunized.”
Discussion
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