Pertussis Vaccine: Limited Efficacy and Increased Risk of Infection

1. Pertussis Vaccine - Total Failure Within 5 Years More recent studies show that by 5 years after completion of a DTaP series, children were up to 15 times more likely to acquire pertussis compared to the first year after the series. Studies have also documented rapid decline in pertussis antibodies within as few as 2–3 years of the most recent aP vaccination, often to pre-vaccination levels and although antibody levels alone are not necessarily indicative of waning immunity, in this case given the higher risk of infection after aP vaccine with time, it is strongly suggestive of it.

2. Pertussis Vaccine Increases the Risk of Contracting Pertussis In the last 13 years, major pertussis epidemics have occurred in the United States, and numerous studies have shown the deficiencies of DTaP vaccines, including the small number of antigens that the vaccines contain and the type of cellular immune response that they elicit. Because of linked-epitope suppression, all children who were primed by DTaP vaccines will be more susceptible to pertussis throughout their lifetimes, andthere is no easy way to decrease this increased lifetime susceptibility.

3. Vaccinated Individuals are More Likely to Spread the Disease “In this paper, we have presented empirical evidence from both case and genomic data for asymptomatic B. pertussis transmission following the switch from the wP to the aP vaccine in the US and UK.  Then, using mathematical and computational transmission models, we have demonstrated that an aP vaccine which blocks symptomatic disease but not asymptomatic transmission is able to account for the observed increase in B. pertussis incidence. Public health authorities may be facing a situation similar to that of polio, where vaccinated individuals can still transmit infection.”

4. Pertussis Vaccination Has Increased Parapertussis Infections "We show that aP vaccination helped clear B. pertussis but resulted in an approximately 40-fold increase in B. parapertussis lung colony-forming units (CFUs). Such vaccine-mediated facilitation of B. parapertussis did not arise as a result of competitive release; B. parapertussis CFUs were higher in aP-relative to sham-vaccinated hosts regardless of whether infections were single or mixed. Further, we show that aP vaccination impedes host immunity against B. parapertussis-measured as reduced lung inflammatory and neutrophil responses. Thus, we conclude that aP vaccination interferes with the optimal clearance of B. parapertussis and enhances the performance of this pathogen. Our data raise the possibility that widespread aP vaccination can create hosts more susceptible to B. parapertussis infection."

5. Vaccine Failure Has Led to Pertussis Resurgence "The observation that aP, which induces an immune response mismatched to that induced by natural infection, fails to prevent colonization or transmission provides a plausible explanation for the resurgence of pertussis and suggests that optimal control of pertussis will require the development of improved vaccines."

6. Widespread Bordetella Parapertussis Infections The number of B. parapertussis infections observed in Wisconsin during October 2011–December 2012 (n = 443) is the largest reported in the United States. Observations of B. parapertussis infections, including a mixed outbreak of B. pertussis, B. parapertussis, and B. holmseii infections in Ohio during 2010–2010, have been reported recently in the United States, likely because of increased use of PCR testing to detect B. parapertussis. Despite increased testing, the burden of B. parapertussis infection in the United States is challenging to measure because testing that differentiates Bordetella species is not universal. This percentage of Bordetella specimens positive for B. parapertussis is similar to previous observations in Wisconsin (culture: 11.9%; PCR: 14.3% and in other states (range: 10%–14.9%), which indicates that infection with B. parapertussis is endemic in the United States and will be identified when testing for B. parapertussis is routinely conducted.