The Victor Central School District announced on Oct. 16 that one of its students in the senior high had been diagnosed with whooping cough, or pertussis. In response to a query, the district stated that the student's vaccinations were "up to date". A Democrat & Chronicle story on Oct. 16 reveals that the student has returned to class after treatment.
Pertussis is the medical name for the illness commonly called whooping cough. It is a highly contagious respiratory illness for which there is a vaccine. The pertussis vaccine is a series of injections. The Centers for Disease Control (CDC) describes the immunization schedule:
Infants and children should get 5 doses of DTaP for maximum protection. A dose is given at 2, 4 and 6 months, at 15 through 18 months, and again at 4 through 6 years. A booster dose of Tdap is given to preteens at 11 or 12 years of age
How is it possible for a patient to be up to date with pertussis vaccinations and still become ill? The answer is complex, and has to do with the formula used in the vaccine, the patient's age and the response by the patient's immune system to vaccination. The CDC points out that having whooping cough only provides immunity from reinfection for a few years.
The 5 doses of DTaP given before a child begins school provide protection that wanes over the next several years. The CDC states that the vaccine will be about 90 percent effective in the first year after the fifth dose is given and then there will be "a modest decrease in effectiveness in each following year." The current formula was implemented in the mid 1990s to replace a more effective formulation that had rare but serious side effects.
Data on the effectiveness of the Tdap booster in preventing pertussis is slim. The formulation was licensed in 2005. The CDC believes that it is about 70 percent effective. The CDC recommends this booster be given to pregnant women and those caring for infants as a protective measure. Infants have little or no immunity to whooping cough and are at greatest risk for complications and death from the illness.
Whooping cough begins as a mild respiratory infection. The characteristic heavy cough may begin around the end of the first week and last for 5 to 10 weeks. The CDC calls the symptom "Paroxysms (fits) of many, rapid coughs followed by a high-pitched "whoop"." Patients may still suffer the cough after recovering from the illness. The illness and the cough may be milder in patients with immunizations and adults may not experience the "whoop" at all.
Pertussis is a bacterial infection and will respond to treatment with antibiotics. Early treatment is important to prevent the spread of the illness. Patients are considered no longer contagious after five days of antibiotics. The CDC has this to say about treating undiagnosed patients with a symptom history of at least three weeks:
If the patient is diagnosed late, antibiotics will not alter the course of the illness and, even without antibiotics, the patient should no longer be spreading pertussis.