An animal study by US Food and Drug Administration (FDA) scientists suggests that administration of either the acellular or the whole-cell vaccine may not prevent the spread of pertussis to unvaccinated animals.
The United States has seen a resurgence of pertussis over the past 3 decades. Many possible explanations for this have been proposed, including pockets of vaccine refusal and reduced effectiveness of the newer acellular pertussis vaccine compared with the older whole-cell pertussis vaccine.
Kuehn BM. Pertussis Vaccine May Not Prevent Spread. JAMA. 2014;311(4):350. doi:10.1001/jama.2013.285867