Based on an animal model, the study conducted by the U.S. Food and Drug Administration (FDA) and published November 25, 2013… shows that acellular pertussis vaccines licensed by the FDA… may not prevent infection from the bacteria that causes whooping cough in those vaccinated or its spread to other people…
Whooping cough rates in the United States have been increasing since the 1980s and reached a 50-year high in 2012.
There are two types of pertussis vaccines, whole-cell [DTP] and acellular [DTaP or Tdap].
In response to concerns about the side effects of the whole cell pertussis vaccine, acellular vaccines were developed and replaced the use of whole-cell pertussis vaccines in the U.S….
The FDA conducted the study in baboons, an animal model that closely reproduces the way whooping cough affects people. The scientists vaccinated two groups of baboons-one group with a whole-cell pertussis vaccine and the other group with an acellular pertussis vaccine currently used in the U.S….
[N]one of the vaccinated animals developed outward signs of pertussis disease after being exposed to B.pertussis.
Animals that received an acellular pertussis vaccine had the bacteria in their airways for up to six weeks and were able to spread the infection to unvaccinated animals.
This research suggests that although indivjduals immunized with an acellular pertussis vaccine may be protected from disease, they may still become infected with the bacteria without always getting sick and are able to spread infection to others, including young infants who are susceptible to pertussis disease.