Doctors Say Whooping Cough Vaccine May Need Booster

SACRAMENTO, Calif. -- For decades, doctors believed that a shot against whooping cough was good for life. But a spike in cases in recent years has proven them wrong.

With growing numbers of teenagers getting the disease -- and spreading it to highly vulnerable infants -- the nation's leading pediatric group is recommending a booster shot for all adolescents.

Although the booster is not now required for admission to school, federal and state health officials are urging pediatricians and family doctors to vaccinate 11- and 12-year-olds and give catch-up vaccinations to older adolescents and adults.

"Where pertussis (whooping cough) is prevalent, which is 80 percent of the United States, that should get done pretty briskly," said Dr. Sarah Long, a chief of infectious diseases at St. Christopher's Hospital for Children in Philadelphia and a member of the American Academy of Pediatrics committee that issued the recommendation earlier this month.

Commonly known as whooping cough, pertussis is a bacterial infection of the respiratory tract that is spread through coughing and sneezing.

Once inside the airways, the pertussis bacteria produce toxins that inhibit the airway's ability to get rid of germs. The disease inflames and damages the lining of breathing passages, and symptoms can last several weeks or longer.

Pertussis gets its nickname from the "whooping" sound that infected children often make while gasping for air after a long coughing spell. Babies -- often unable to sustain the coughing spells -- are particularly vulnerable to complications of the disease.

According to the American Academy of Pediatrics, nearly 29,000 cases of pertussis were reported in the United States last year, a 40-year high, compared with a historic low of 1,010 cases in 1976.

California's overall caseload has mushroomed in 2005, from 747 last year to more than 2,100 this year.

Of the nation's 2004 cases, 34 percent were in adolescents ages 11 to 18. Adolescents and adults whose immunity to pertussis has worn off can easily spread the disease to infants too young to be immunized and often too young to beat back the illness.

"We have been successful in vaccinating kids and reducing pertussis as a whole, but now we are seeing increases in those older age groups," said Dr. Dean Blumberg, a pediatric infectious disease specialist at UC Davis who is active in a California advisory committee on pertussis immunization. "For the 10- to 19-year-old age group there has been a 400 percent increase in the number of reported cases over the last 15 years or so."

Whooping cough deaths among infants have jumped from about 10 per year in the 1990s to about 20 per year since 2000, including seven in California this year.

Experts say that one reason for the higher caseloads is better reporting of the disease, which in the past has been misdiagnosed as a virus, asthma, or other respiratory infection.

Even cases of sudden infant death syndrome have been later shown to be caused by pertussis, said Long. "They don't have the cough that the older child has, but they gag and gasp and turn blue," she said. "It can be devastating very quickly."

In addition, Long said, early childhood immunization has controlled spread of pertussis, making natural immunity from exposure to the disease less likely.

"If you were living in the United States in the 1950s you were getting infected frequently, but you still had immunity and kept getting boosted," she explained. "Now, because the immunity has waned, when you get an infection it's more likely to make you sick."

Symptoms of whooping cough include runny nose, sneezing, low-grade fever and a mild, occasional cough that can appear to be the common cold.

But after one or two weeks, a pertussis patient begins to experience bursts of coughs that can result in a whoop, or even vomiting.

Treatment with antibiotics shortens the course of the disease, which otherwise can last months, and also prevents further contagion.

Current immunization guidelines published by the Centers for Disease Control and Prevention recommend children get five doses of the pertussis vaccine before their sixth birthday. The shot includes protection against tetanus and diphtheria.

The American Academy of Pediatrics, backed by the CDC's Advisory Committee on Immunization Practices, now recommends that adolescents 11 to 18 get a single dose of a combination booster shot, preferably at age 11 or 12. The ACIP also recommends adults get the booster.

The booster for adolescents, produced by GlaxoSmithKline Biologicals and approved in the U.S. last spring, is now widely available. Another booster made by Sanofi Pasteur was approved for use in people ages 11 to 64 in June.