Pertussis Vaccine's Effectiveness May Be Short Lived
Young children who are immunized against whooping cough (pertussis) are well protected against this illness, but a new study finds that the vaccine's effectiveness declines sharply after just three years.
David Witt, M.D., at Kaiser Permanente Medical Center in San Rafael, Calif., and his colleagues sifted through the medical records of about 15,000 children in an attempt to figure out why that region was experiencing an outbreak of pertussis.
They found 171 confirmed cases of pertussis between March and October 2010. Of that number, 103 were in children ages 12 or younger. On closer examination, Dr. Witt determined that the number of pertussis cases "skyrocketed" once children reached age 8.
Preteens seem to be at highest risk for contracting pertussis, he says. Infants and preschoolers who are up to date on their pertussis vaccinations are protected against the disease, but as children move into later childhood, their immunity seems to wane. In fact, the rate of infection was the same in the 8- to 12-year-old age group for children who had been immunized and those who had not.
Dr. Witt says the number of pertussis cases dropped off again as children got their booster shot at age 12.
Although many of the preteens who fell ill had only a mild case of the disease, the real threat in a pertussis outbreak is the transmission to other family members, especially infants. Infants younger than 6 months have not yet received their third dose of the vaccine and so are more vulnerable to the infection.
Dr. Witt, who presented his findings at a recent conference of the American Society for Microbiology, isn't recommending that the pertussis booster be given earlier than age 12. Although he and his colleagues did do so successfully during last year's outbreak, more research is needed to confirm his findings.
Always talk with your health care provider to find out more information.
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Whooping cough, or pertussis, usually takes one to three weeks to incubate, and a child usually passes through three stages. The following are the most common symptoms of whooping cough, according to each stage.
Catarrhal stage (often lasts one to two weeks):
- Mild cough
- Low-grade fever
- Runny nose
Acute phase (may last for several weeks):
- Cough gets worse and comes in severe fits
- Cough is dry and harsh
- Cough ends with a whoop sound on inspiration
- Child may vomit with the coughing and appear to be strangling on the vomit
- Cough can be started by many factors, including feeding, crying, or playing
Recovery phase (usually begins around the fourth week):
- Vomiting and the whooping cough cease first
- The cough usually decreases around the sixth week but may continue on occasion for the next one to two months
Whooping cough can last up to several weeks and can lead to pneumonia.
The symptoms of whooping cough may resemble other medical conditions.
Always talk with your health care provider to find out more information.
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