Morning Edition, May 26, 2009

Over the past 10 years, a highly contagious and sometimes fatal bacterial disease once thought eradicated from the U.S. has re-emerged, threatening the very youngest and weakest of our population. Pertussis is a bacterial infection of the lungs and spreads from person to person through moisture droplets in the air, probably from coughs or sneezes. A person with pertussis develops a severe cough that usually lasts four to six weeks or longer.

Health officials cite an increase in the incidence of pertussis, particularly among infants and teenagers. In 1976 there were just over 1,000 reported cases of pertussis in the United States; by 2004, it climbed to nearly 26,000 cases. Between 2000 and 2005 there were 140 deaths resulting from pertussis in the United States.

At the same time, both studies and anecdotal reports from doctors nationwide report an increase in the number of parents refusing to vaccinate their children against childhood diseases.

Much of this refusal has to do with perceived vaccine safety issues, such as purported associations between vaccines and autism, attention deficit disorder, seizures and epilepsy. None of these concerns have been upheld in research. In fact, all scientific studies show vaccines to be highly effective and safe, with only rare, moderate adverse side effects.

Results of this current study show the biggest risk among children who are not vaccinated is the disease itself as well as spreading it to more vulnerable populations who are unable for age or medical reasons to get vaccinated.

Coughing occurs in sudden uncontrollable bursts where one cough follows the next without a break for breath. Many children make a high-pitched whooping sound when breathing in after a coughing episode, hence the nickname "whoop-ing cough." Coughing can be so severe patients can vomit or break ribs.

Their face or lips may look blue from lack of oxygen. The cough is often worse at night. Between coughing spells, the person seems well, but the illness is exhausting over time. Coughing episodes gradually become less frequent but may continue for several weeks or even months until the lungs heal.

Anyone of any age can get pertussis. Older children and adults usually have a less severe illness but they can still spread the disease to infants and young children.

Pertussis in infants is often severe and infants are more likely than older children or adults to develop complications, the most common of which is bacterial pneumonia. Rare complications include seizures, inflammation of the brain and death.

In this study, published in the June issue of the journal Pediatrics, researchers from Kaiser Permanente Colorado's Institute for Health Research used electronic health records to look for immunization refusal and possible pertussis infections.

Specifically, researchers examined the medical records of children between the ages of two months and 18 years who were members of Kaiser Permanente Colorado between 1996 and 2007. First investigators confirmed which children had pertussis infections. Next, they verified whether parents had refused some or all vaccines for their children.

The findings: Children of parents who refused the DTaP vaccine were 23 times more likely to get whooping cough compared to fully immunized children. "A 23 fold increase is huge!" says Jason Glanz, Ph.D., a senior scientist at Kaiser Permanent's Institute for Health Research who headed the study.

Glanz says the findings should help "dispel one of the commonly held beliefs among vaccine-refusing parents: that their children are not at risk for vaccine preventable diseases."

And, from a larger perspective, Glanz adds the findings also show " that the decision to refuse immunizations could have important ramifications for the health of the entire community. Based on our analysis, we found that one in ten additional whooping cough infections could have been prevented by immunization."

Glanz, as a father of young children himself, says vaccines "can pose confusing and difficult choices." He adds that is why the purpose of the study was to give parents more information to weigh the benefits and risks, as well as provide pediatricians with more information to help them participate in the discussion.

For the physician, "it's an uphill battle", says Glanz, since most physicians today have so little time to spend with parents and it's difficult to discuss the risks and benefits of vaccines with parents who have lots of questions and want thorough answers.

On top of that, physicians are battling a lot of misinformation, says Glanz. The internet, for example, is easily accessible and often misleading, with numerous scary descriptions of devastating diseases purported to result from vaccines.

All this adds up to a critical need for the public health community to develop effective "risk communications messages" that "resonate with parents" in order to help them make truly informed decisions about vaccinating children.

Doctors need simple targeted information about actual risks of having the vaccine and risks of not having it. They need to know, says Glanz, that their child could actually become infected by the pertussis bacteria.

In addition, it should be very clear among parents, says Glanz, "is that by keeping immunization rates high, we protect everyone, including the most vulnerable populations."

There are a number of individuals for whom vaccination against pertussis is not possible. The vaccination is not effective for babies under two months old because their immune system is not yet fully developed and capable of responding.

Then, there are older children who suffer other medical conditions which compromise their immune system and also make pertussis vaccination ineffective. When parents protect their own child, says Glanz, they "also protect this most vulnerable population."

Dr. Randy Bergen is a pediatrition who specializes in infectuous disease. He says some of the most compelling data he's seen comes from the state of California which reports that between 2001 and 2006, there were 24 deaths from pertussis. All of those deaths occurred in infants under two months of age.

The only way to protect these infants, says Dr. Bergen, is by "cocooning, where we immunize and protect those around the infants, and that's where the real concern is, especially when it comes to pertussis; that by not vaccinating school age children, adolescents and young adults, we're leaving these infants unprotected."

Dr. Bergen suggests that ironically, vaccines are almost victims of their own success. "Unfortunately vaccines have been so successful in reducing diseases that not only are parents unaware of the potential severity of these diseases, but many pediatricians have rarely seen them and don't know the potential severity of these diseases either."

The recent number of infant deaths from pertussis should certainly serve as a wake-up call. As for vaccine safety, Bergen says there have been a large number of studies which have looked at safety over the last 10 years: "None of these studies have proved any association between a vaccine, a preservative in a vaccine or a combination of vaccines, and significant adverse problems." Vaccines in this country are very safe, he adds; they "prevent diseases that can maim and kill."

The childhood vaccine, DTaP, is a three-in-one immunization that protects against diptheria, pertussis, and tetanus. It is given in a series to children at two months, four months, six months and 15-18 months of age. A booster is given before kindergarten. The DTaP vaccine, like other routine childhood immunizations, has been shown to be more than 98 percent effective.

Recent outbreaks of pertussis among teenagers have led to investigations about the long term efficacy of the vaccine. They conclude that potency wanes as children get older. Today, federal health officials recommend teenagers also get a booster shot, probably at around 11-13 years old.