A growing number of children aren't getting required vaccinations for non-medical reasons. What will this new reality bring this school year?
As parents send their children back to school, some are grappling with a new worry: whether their children's classmates have received all their vaccinations.
An outbreak of measles in Texas this week shows why their concern is not without reason. Twenty-one people linked to a megachurch and its congregation have contracted the highly contagious disease, and the case has put a spotlight on falling vaccination rates in the U.S.
Measles was eradicated in the U.S. as of 2000, according to the Centers for Disease Control and Prevention, but outbreaks like the one in Texas are increasing, as is the percentage of parents choosing not to immunize their children, which has seen an uptick in recent years. Usually, the CDC expects to see 60 cases of measles per year, but there have been 135 cases of measles so far in 2013, and in 2011, more than 220 people were diagnosed with the disease.
This latest outbreak follows a rash of recent measles cases among New York's Orthodox Jewish population and an outbreak in San Diego in 2008.
"Many parents are withholding their children completely or are delaying [the vaccines], spreading them out," explained Dr. William Schaffner, a professor of preventive medicine and infectious diseases at Vanderbilt University School of Medicine. "Both create a population of susceptible children."
The children infected in Texas were home-schooled, but the rate of exemptions to school immunization requirements is also on the rise, according to CDC data. A 2012 analysis in the New England Journal of Medicine looked at exemption rates between 2006 and 2011 nationwide (excluding Mississippi and West Virginia, which do not allow non-medical exemptions) and found overall rates rose nearly a percentage point, a small but statistically significant increase.
Children in the U.S are required to be up-to-date on their vaccinations in order to attend school, but this so-called "No Shots, No School" mandate is not a federal law and the requirements vary from state to state. States like California and Oregon are "very permissive" when it comes to exemptions, Schaffner said. In Oregon, rates of non-medical exemptions reached an all-time high of 6.4 percent in the 2012-2013 school year, the highest rate in the country.
"Parents should be interested and perhaps concerned if exceptions are permitted too readily," Schaffner said.
The CDC calls measles the "most deadly" of all childhood illnesses, and recommends that children receive the measles, mumps and rubella (MMR) vaccine in two doses, at age 12-15 months and again sometime before the start of kindergarten, as part of a vaccine schedule that includes more than 30 shots by the age of 6.
Many parents who choose not to immunize their children still cite concerns over purported links between immunizations and autism, although the CDC states definitively that research has shown that "vaccines are not associated with autism spectrum disorders."
In addition to measles, other diseases that have seen resurgences in recent years include pertussis, or whooping cough, German measles and some cases of polio.
"I am extremely concerned that my children may be in close contact through school or extracurricular activities with children who have not been immunized," said Maria Termini-Romano, a mother of three and nurse practitioner in Havertown, Penn. "My children are being put at unnecessary risk of contracting communicable diseases that can be life-threatening to children."
A Scientific American analysis of CDC data found that rates for MMR and DTP (diphtheria, tetanus and pertussis) vaccinations are falling, with some states dropping below the threshold for what's known as "herd immunity."
"Vaccines have two functions," Schaffner explained. "They protect the individual, but if many of us are vaccinated we also protect the frail among us," such as infants who are too young to be vaccinated or individuals who cannot be vaccinated for medical reasons.
Schaffner called measles a "nasty disease, even when uncomplicated" and said he believes that part of the problem is a lack of awareness on the part of "misinformed" parents of just how devastating these infections can be.
Many parents "would be amazed to learn that before we had the measles vaccine, 400 children each year in the U.S. died of measles and its complications. This cultural understanding that's handed down from generation to generation got broken because of our effective immunization programs."
In fact, he said, the first cases in these outbreaks are often misdiagnosed, because "we have two generations of physicians that have never seen these diseases."
According to the CDC's data for the 2012-2013 school year, the nationwide vaccine exemption rate was 1.8 percent. While low, the report noted that "low vaccination and high exemption levels can cluster within communities, increasing the risk for disease."
The state with the lowest immunization rate for measles was Colorado, at 85.7 percent, and the highest was Mississippi, at 99.9 percent. Texas, the site of the most recent outbreak, had a statewide measles vaccination rate of 97.5 percent.
"We are putting future generations at risk for morbidity and mortality related to diseases that had all but been eradicated by the scientific breakthroughs of immunizations against these deadly diseases," said Termini-Romano. "As parents, we have been the beneficiaries of our own parents' forethought and careful consideration of our health as adults. I think our children deserve nothing less."
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