The pertussis, or whooping cough, vaccine given to children before they begin school might lose its effectiveness sooner than previously thought, according to a study from Kaiser Permanente Medical Center in San Rafael, the San Francisco Chronicle reports (Allday, San Francisco Chronicle, 9/20).
The preliminary study -- led by David Witt, chief of infectious diseases at the medical center -- examined about 15,000 children in Marin County, including 132 who contracted pertussis last year (Stobbe, AP/Boston Globe, 9/19).
The results of the study have not yet been published (San Francisco Chronicle, 9/20). Witt discussed the study on Monday at the American Society for Microbiology conference in Chicago.
Government officials suggest that children receive vaccinations against whooping cough in five doses. The first shot is recommended at age two months, and the final shot between ages four and six. Children are supposed to be vaccinated again by age 11 or 12 (AP/Boston Globe, 9/19).
Public health experts had assumed the childhood vaccine offered strong protection against whooping cough for at least seven years (San Francisco Chronicle, 9/20).
In California last year, more than 9,100 individuals became ill and 10 infants died from whooping cough.
This fall, California schools have turned away thousands of middle and high school students because they have not received the whooping cough vaccination, as required by a new state law (AP/Boston Globe, 9/19).
Key Study Findings
Witt found that children who had gone at least three years since having the last of their shots were up to 20 times more likely to contract the disease than children who had been vaccinated more recently.
Children ages eight to 12 had the most cases of whooping cough (AP/Boston Globe, 9/19). About 80% of the children diagnosed with the disease already had been vaccinated (San Francisco Chronicle, 9/20).
The report also found that the rates of whooping cough dropped significantly among children who are 11 to 12 years old, an age when many receive a booster shot (AP/Boston Globe, 9/19).
Witt said the study suggests that public health officials might want to take a more aggressive approach toward vaccination and require children to receive the shots earlier.
He added that the results of his research will need to be confirmed in a larger study (San Francisco Chronicle, 9/20).