Medical investigators researching whooping cough vaccine

Medical investigators recently traveled to California, which is experiencing its worst pertussis, or whooping cough, outbreak in the last 60 years, to study the effectiveness of a vaccine that has been in use since 1997.

The CDC's project will be conducted with help from the Department of Public Health, reports. Together, the institutions plan to evaluate the effectiveness of a pertussis vaccine that has been given to children since 1997. They are looking to find out whether or not it has lost some of its potency sooner than expected.

The vaccine tests are beginning in San Louis Obispo County, but it is expected that they will move to other counties, including San Diego, over the next few weeks.

“The vaccine effectiveness evaluation is a priority for us, so we’d like to have results within months,” Stacey Martin, a CDC epidemiologist, said, according to

Health officials determined the necessity of the study after the realization that a significant number of seven to 10-year-olds who received the five dose pertussis vaccination were becoming ill. Immunity was originally believed to last until age 11, when a booster shot was recommended.

The 1997 vaccine being questioned is acellular and replaced a whole-cell version that had been in use since the 1940s. The acellular version uses fragments of pertussis bacteria to stimulate the recipient’s immune system instead of whole bacteria, which could cause major side effects.

Martin cautioned that the CDC’s probe should not keep parents from immunizing their children because its protection rate is still statistically at 80 to 90 percent, reports.

“It’s our best tool for preventing serious illness and deaths,” Martin told “We just want to make sure that the timing is appropriate (for a subsequent booster shot) and that we’re giving the best protection available.”