A wholly acellular pertussis vaccine series increased disease risk when compared with the traditional whole-cell vaccine that it replaced, according to study data published online.
David J. Witt, MD, of the department of infectious diseases, Kaiser Permanente Medical Center, and colleagues published data on 904 patients with pertussis who were identified from a Kaiser Permanente database of more than 263,000 members aged 8 to 20 years.
“In patients with a full history of vaccinations, those with five total doses of only [acellular pertussis vaccine (aP)] had an 8.57 RR of pertussis (P<.0001) contrasted to those with one or more [whole-cell pertussis vaccine] dose,” Witt and colleagues wrote. “With six doses of aP, the RR of disease was 3.55 (P<.0001).”
The researchers noted some study limitations; specifically that the study was retrospective, and that pertussis testing was at the individual clinician’s discretion, which may have biased results.
Regardless of the study limitations, the researchers said: “Finding of waning immunity associated with ongoing outbreaks of pertussis argues for earlier booster doses of aP vaccine, on a routine basis and particularly in an outbreak setting, and clearly is a call for development of more effective and durable pertussis vaccines.”