Whooping cough shot wears off

Study finds children susceptible after three years

A California study has concluded the whooping cough vaccine given to young children before they enter school wears off after three years, well before booster shots are typically administered.

The research, led by Dr. David Witt of the Kaiser Permanente Medical Center in San Rafael, found that children who had gone three years or longer since the last of their recommended five-shot series were up to 20 times more likely to become infected than children who had been recently vaccinated, according to media sources. Children usually receive their last shot between 4 and 6 years old.

“I was disturbed to find maybe we had a little more confidence in the vaccine than it might deserve,” said Witt.

The study, which looked at approximately 15,000 children in Marin County, comes on the heels of more than 9,000 whooping-cough infections and the death of 10 infants in California last year.