Acellular Pertussis Vaccine Less Effective than Whole-Cell Vaccine

The no-longer-used whole-cell pertussis vaccine is significantly more effective in preventing cases of whooping cough than the acellular vaccine, which replaced the whole-cell option in 2001 and is now the exclusive method for preventing the disease. 

According to the health records of Kaiser Permanente, there was an 8.57-fold increase in the relative risk of experiencing pertussis for those who received 5 total doses of the acellular vaccine compared with those who received the whole-cell vaccine.

"The attack rate of pertussis was substantially lower among persons who had received at least one dose of their vaccine series doses as whole cell pertussis," said Maxwell A. Witt, research assistant at Kaiser Permanente Medical Center, San Rafael, California.

After studying the records of 463,091 patients between the ages of 8 years and 20-years-old, grouping them by the number of vaccines patients received, researchers found significantly lower attack rates of pertussis in those patients who received at least 1 whole-cell pertussis vaccine.

"Waning herd immunity to pertussis is associated with the retirement of whole cell pertussis,” researchers concluded.

"The current generation of children is the first to have been vaccinated solely with acellular pertussis vaccine for which our findings would predict a significant population of under-protected children," Witt said. "Recent pertussis outbreaks in the United States had peak attack rates among those who are in the exact age groups solely vaccinated with acellular pertussis vaccine."

-Michael Potts