Fatal Exemption

by Dr Paul A. Offit

The Journal of the American Medical Association (JAMA) recently published a study that received little attention from the press and as a consequence, from the public. The study examined the incidence of whooping cough (pertussis) in children whose parents had chosen not to vaccinate them. The results were concerning.

Vaccines are recommended by the Centers for Disease Control and Prevention (CDC) and professional societies, such as the American Academy of Pediatrics. But these organizations can't enforce their recommendations. Only states can do that -- usually when children enter day-care centers and elementary schools -- in the form of mandates. State vaccine mandates have been on the books since the early 1900s; but they weren't aggressively enforced until much later, as a consequence of tragedy.

In 1963 the first measles vaccine was introduced in the United States. Measles is a highly contagious disease that can infect the lungs causing fatal pneumonia, or the brain causing encephalitis. Before the vaccine, measles caused 100,000 American children to be hospitalized and 3,000 to die every year. In the early 1970s, public health officials found that states with vaccine mandates had rates of measles that were 50% lower than states without mandates. As a consequence, all states worked toward requiring children to get vaccines. Now every state has some form of vaccine mandates.

But not all children are subject to these mandates. All 50 states have medical exemptions to vaccines, such as a serious allergy to a vaccine component. Some 48 states also have religious exemptions; Amish groups, for example, traditionally reject vaccines, believing that clean living and a healthy diet are all that are needed to avoid vaccine-preventable diseases. And 20 states have philosophical exemptions. In some states these exemptions are easy to obtain by simply signing your name to a form; and in others they're much harder, requiring notarization, annual renewal, a signature from a local health official, or a personally written letter from a parent.

The JAMA study examined the relationship between vaccine exemptions and rates of disease. The authors found that between 1991 and 2004 the percentage of children whose parents had chosen to exempt them from vaccines increased by 6% per year, resulting in a 2.5-fold increase. This increase occurred almost solely in states where philosophical exemptions were easy to obtain. Worse, states with easy-to-obtain philosophical exemptions had twice as many children suffering from pertussis -- a disease that causes inflammation of the windpipe and breathing tubes, pneumonia and, in about 20 infants every year, death -- than states with hard-to-obtain philosophical exemptions.

The finding that lower immunization rates caused higher rates of disease shouldn't be surprising. In 1991 a massive epidemic of measles in Philadelphia centered on a group that chose not to immunize its children; as a consequence nine children died from measles. In the late 1990s, severe outbreaks of pertussis occurred in Colorado and Washington among children whose parents feared pertussis vaccine. And in 2005 a 17-year-old unvaccinated girl, unknowingly having brought measles with her from Romania, attended a church gathering of 500 people in Indiana and caused the largest outbreak of measles in the U.S. in 10 years -- an outbreak limited to children whose parents had chosen not to vaccinate them. These events showed that, for contagious diseases like measles and pertussis, it's hard for unvaccinated children to successfully hide among herds of vaccinated children.

Some would argue that philosophical exemptions are a necessary pop-off valve for a society that requires children to be injected with biological agents for the common good. But as antivaccine activists continue to push more states to allow for easy philosophical exemptions. more and more children will suffer and occasionally die from vaccine-preventable diseases.

When it comes to issues of public health and safety, we invariably have laws. Many of these laws are strictly enforced and immutable. We don't allow philosophical exemptions to restraining young children in car seats, to smoking in restaurants or to stopping at stop signs. And the notion of requiring vaccines for school entry, while it seems to tear at the very heart of a country founded on the basis of individual rights and freedoms, saves lives. Given the increasing number of states allowing philosophical exemptions to vaccines, at some point we will to be forced to decide whether it is our inalienable right to catch and transmit potentially fatal infections.

Dr. Offit is chief of the division of infectious diseases at the Children's Hospital of Philadelphia.

This article originally appeared in the The Wall Street Journal on January 20, 2007, and is reproduced with the permission of the author.