Current Pertussis Vaccine Mounts a Weaker Recall Response with Booster Shots

Researchers at the La Jolla Institute for Allergy and Immunology have found individuals who had been inoculated with the newer pertussis (whooping cough) vaccine as part of their initial series of shots mount a weaker recall response when receiving booster shots later on. Specifically, the study found the new vaccine, which replaced the original vaccine in 1996, fell short of generating a robust T cell response, which provides the long-term memory that allows the immune system to mount a rapid response if exposed to the pathogen. “Ideally, you should engage both arms of a protective response against pathogens — B cells that produce antibodies and T cells that generate long-term memory,” said Ricardo Antunes, PhD, a postdoctoral researcher and first author of the study. “But, apparently, the new vaccine fails to generate an adequate T cell response. Although B cells are a very important component of vaccine efficacy, the important role of T cells is being more and more appreciated and the key point of our study is to show that there are striking differences in the T-cell response to the two different vaccines.”

In the study, researchers recruited 114 healthy adults who had been originally vaccinated with the whole pertussis (wP) vaccine (the original vaccine crafted from dead bacteria that came with unwanted side effects) or the acellular pertussis (aP) vaccine (the new vaccine that relies on purified bacterial proteins to induce immunity) in infancy and administered booster vaccinations with aP in middle and high school and as adults, and analyzed their immune response at regular intervals. Their results showed that priming in the first few months after birth with the aP or wP vaccines induces different T-cell responses. And, while both are initially capable of generating protective immunity, differences evolve over more than 15 years. In addition, T cells originally primed with aP gradually lose the ability to respond to booster vaccination. “These cells just sit there and do nothing while T cells primed with wP respond with a pronounced boost,” said Dr. Antunes.

The study was conducted because the birth years of the teenagers and young adults most affected by the sudden increase in pertussis cases coincided with the nationwide switch from the wP to the aP vaccine. According to the researchers, unraveling the differences between thetwo vaccinesis key to understanding how to better prevent whooping cough and may also provide important lessons on vaccine efficacy in general.