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Halting the Backward Slide toward Epidemic

Commentary by Hildegund C. J. Ertl, M.D.

A decade ago, if someone told me that we might willingly sacrifice our collective immunity to pertussis—whooping cough—I would likely have considered that person to possess a dark view of humanity. Sadly, I would have been wrong to do so. Last week, the US Centers for Disease Control pronounced that 2012 is on track to be the worst year for pertussis since 1959, which saw at least 40,000 cases of the disease in the United States.  Here in Pennsylvania, alone, there have been over 900 cases reported. (See "Whooping cough cases are rising at epidemic rate," and "Pertussis outbreak may be worst in 50 years, CDC says.")

Chances are, if you are under the age of 50, you have never experienced or witnessed whooping cough. Certainly, today’s parents have been spared hearing the coarse bark of their children gasping for breath. For adults, whooping cough represents a bad cold with a bad cough. For far too many infants, however, it represents a horrible way to die.  The wracking cough alone is painful and violent enough to cause seizures in infants, but death usually occurs from the resulting pneumonia. Already, nine children in the US have died from pertussis infection this year. 

Granted, nine is a far cry from the 10,000 children thought to have died from the disease each year before the first pertussis vaccine was created. However, because this disease is preventable and because we have the power to prevent it, those nine deaths could easily have been prevented.

There is a concept in vaccination that everyone must understand: it is called herd immunity. It means that we protect the most vulnerable parts of our society by creating a wall of protection around them by getting vaccinated. Some people cannot be vaccinated, such as infants less than two months of age or people with immunological disorders. And some people who are vaccinated simply fail to acquire immunity. But the collective immunity of the masses, granted through vaccines, protects all.

Pertussis results from infection by a highly contagious bacterium. The disease spreads at an alarming rate. As a result, while the modern pertussis vaccine is thought to be 80 to 85 percent effective, herd immunity against pertussis requires near-universal vaccination.  Vaccination rates, however, continue to slip downward. As a society, we are poking holes in our herd immunity at the risk of our children’s lives.

And so, there appears to be two factors driving this explosion of new pertussis cases. First is the persistent and erroneous notion among some parents that vaccines are either ineffective or potentially dangerous, causing disorders such as autism. There are possible side effects to any vaccine, of course, but it has been proven time and again that autism is not one of them.

Second, and perhaps linked to the first, is that we are failing to receive pertussis booster shots. There is some evidence that shows that the immunity granted by pertussis vaccination is not all that long lived. While research may reveal new ways of boosting the longevity of immunization, there is already a simple fix to, if that is indeed the case: booster immunizations. Each missed booster becomes another hole in the protective barrier against disease.

I ask you to do three simple things: 1) get your pertussis booster shot, 2) encourage your friends and family to vaccinate, and 3) support vaccine research.  Only then can we halt this unnecessary and potentially disastrous backward slide.

Hildegund C. J. Ertl, M.D., is the Caspar Wistar Professor in Vaccine Research and director of The Wistar Institute Vaccine Center.