Junkfood Science: Weighing the risks of vaccinating children for whooping cough

May 28, 2009

Weighing the risks of vaccinating children for whooping cough

Loving parents have a hard job. They want to protect their children from harm and make the best healthcare decisions for them, but with all of the health information and misinformation swirling around, it can seem impossible to know what to believe. One question for some parents is whether childhood immunizations are necessary anymore. With fewer children dying of childhood illnesses today, it can seem like the diseases are no longer serious and that the vaccines might be putting their children at needless risk.

Researchers, led by Dr. Jason Glanz, Ph.D., a senior scientist at Kaiser Permanente's Institute for Health Research, wanted to get parents the most accurate information possible on immunizations in order to help them make the best decisions for their children. They conducted a study, just published in the June issue of Pediatrics, looking at every case of pertussis infection identified in children in the Kaiser Permanente of Colorado health plan over more than a decade, between 1996 and 2007. They randomly matched each case to four controls and looked at the children’s vaccination records. The differences were striking. Only 0.5% of the healthy children had not been vaccinated, compared to 12% of the children who had gotten sick with pertussis.

That means, unvaccinated children are associated with a nearly 23-fold higher risk of getting the disease compared to vaccinated children. [Now this is a tenable correlation and real relative risk.] Deciding not to vaccinate children does not keep them safer from childhood diseases, but puts them at considerably greater risk.

Pertussis, commonly called whooping cough, is a highly contagious infection due to Bordetella pertussis. It is a serious respiratory infection that begins with cold symptoms that last a week or so, when people are the most contagious. Then, it progresses to the paroxysmal stage, which can last up to ten weeks. That’s characterized by intense attacks of severe coughing, around 15 episodes a day, that result in “whoop” sounds as the patient tries to gasp for breath between coughs. Babies and others can stop breathing and turn blue, and often vomit from coughing so hard.

The vast majority of pertussis cases (88.2%) are in children under ten years old. Before the vaccine was introduced in the 1940s, pertussis was a major cause of death among infants and children in the United States. It still is in many parts of the world. The World Health Organization reported more than 200,000 pertussis-related deaths in 2000. With our increasingly mobile society and people traveling around the world, the likelihood of children in our country being exposed to someone who is infected also increases.

Parents clearly cannot rely on other children in their local schools being vaccinated to offer sufficient “herd immunity” to eliminate the need for their own children to be vaccinated. But vaccinating isn’t only to protect their own child — it’s to help protect the most vulnerable children in the community, especially infants who are too young to be vaccinated.

Nearly all fatal cases of pertussis occur in infants under six months of age, who are too young to have been immunized, said pediatrician Dr. Hazel Guinto-Ocampo, M.D., with Nemours Children’s Clinic. Young infants this age are more likely to get sickest with pertussis, with 69% requiring hospitalization. They’re also more likely to develop complications that include pneumonia, which affects one in five babies, brain swelling encephalopathy and seizures in one percent, and failure to thrive. Among older children, teens and adults, the complications can include pneumonia, rib fractures, incontinence and exhaustion.

Preemies and young infants; and children with heart, lung or neurological health problems; are at special risk for contracting pertussis and developing complications. Young babies are at the greatest risk of dying, with 1.8% of babies under two months dying, according to the June 6, 2008 issue of the MMWR from the Centers for Disease Control and Prevention (CDC). Pertussis causes an estimated 10–20 deaths each year in the U.S., said the CDC.

Newborns most often get pertussis from being around adults and teens who don’t realize they have the disease. During the first weeks of the illness, symptoms can mimic a common cold or flu, but that’s also when people are the most contagious. That’s why medical professionals are stressing the importance of the DTaP booster shot, which was introduced in 2005, for teens and adults whose immunities wear off. Its importance was learned during the 1980s and 1990s, when reported cases of pertussis increased, most notably among teens and adults, and pertussis-related deaths among babies rose — rising from 61 to 93 deaths between 1980-89 and 1990-99.

Pertussis vaccines are more than 90% effective and after their introduction, pertussis cases dropped to the lowest rates in U.S. history by 1976, according to the CDC. Because of vaccinations, reported cases of pertussis are 50-fold less than they were during the prevaccine era. Childhood vaccinations are one of the safest and most proven measures parents can take to protect their children.

There are so many claims out there trying to scare parents about vaccines, but they are not grounded in any good science. “Vaccines are among the most tested drugs we have,” said Dr. Lance Chilton, M.D., professor of pediatrics at the University of New Mexico and co-chair of the Clinical Prevention Initiative Immunization group. Sure, there are lots of unsupportable preventive public health claims out there, but basic childhood immunizations are not among them. The risks of not vaccinating children are so much greater than the risks of the vaccine.

With this latest study, parents now have information on just how significant those risks can be.

For more information on pertussis and the DTaP vaccine:

Pertussis — Centers for Disease Control and Prevention

Bookmark and Share