Dimitri Diavatopoulos, PhD, on Improving Pertussis Vaccination

Pertussis incidence has increased over the last 20 years and is even prevalent in populations with high vaccination rates. Researchers are working to better understand the challenges associated with controlling pertussis to better track, treat, and prevent the illness.

Speaking on this topic during the World Vaccine Congress Europe was Dimitri Diavatopoulos, PhD, who is an Assistant Professor at the Radboud Center for Infectious Diseases / Laboratory of Medical Immunology at the Radboud University Medical Center in the Netherlands.

He answered a few of our questions about controlling pertussis and the future of the vaccine.

Infectious Diseases Consultant: What are the challenges associated with controlling pertussis worldwide?

 Dimitri Diavatopoulos: The challenges for controlling pertussis are very different dependent on the region of the world that you happen to live in. For instance, low vaccination coverage with diptheria-tetanus-pertussis (DTP) remains a major issue in several low-income countries, particularly in Africa. Increasing the vaccination coverage in these countries would be an essential first step for reducing infant mortality and severe morbidity. Another challenge is that the actual burden of pertussis in many low- and middle-income countries is not well-known because of the lack of adequate surveillance systems. Most pertussis cases are therefore classified purely on clinical observations without laboratory confirmation. As a result, pertussis is significantly underreported.

In several countries that have switched to acellular pertussis vaccines—mostly high-income countries—we see that pertussis incidence has been increasing in the last 10 to 20 years, even in populations with high vaccination coverage. There is strong evidence of circulation in the population, most of which are mild or asymptomatic. However, the high amount of transmission poses a risk of infection for newborns too young to be fully vaccinated. Unfortunately, this is exactly the age group that is at highest risk of developing complications.

ID CON: How are clinical trials evolving to better formulate vaccines to control pertussis?

DD: Clinical trials can really help us understand how the different vaccines work and what aspects of disease or infection they protect against, but also what they do not do. Because it will take several years before novel pertussis vaccines become available, it is important to make optimal use of the currently existing vaccines. This is also where clinical trials can be very useful. The recently established controlled human infection model for pertussis is also very exciting and will provide new options for developing and evaluating new formulations.

ID CON: In your opinion, what has to be done to ensure pertussis incidence is reduced (or eliminated)?

DD: I think that our first priority should be to reduce infant mortality and severe infections due to pertussis. This is something that the current pertussis vaccines actually do pretty well, although there are some concerns about the long-term protection.

The introduction of pertussis vaccination for pregnant women has provided an important new strategy to bridge the vulnerability gap from birth until infants are old enough to be directly protected by vaccination.

In contrast to disease, I think that elimination is really a different question. Since pertussis is such a highly transmittable pathogen, we would not only need to consistently reach a vaccination coverage of close to 95%, but vaccines would also have to provide highly effective and persistent herd immunity. It is very well possible that the immunological mechanisms that are important for protection against disease vs those that are involved in protection against infection are not the same. So for us to move forward and design better formulations, it is essential that we better understand these aspects.

ID CON: What new opportunities for pertussis control have arisen recently?

DD: The implementation of pertussis vaccination programs for pregnant women has helped to reduce pertussis mortality in newborns. Additionally, recent efforts to develop therapeutic antibodies may provide important new options for the clinical care of pertussis patients. In the long run, I think that having more effective new vaccines that induce long-lasting immunity would be ideal.

ID CON: How are vaccine researchers using these opportunities to better produce vaccines?

DD: Within the PERISCOPE consortium (www.periscope-project.eu), we are applying new systems biology-based approaches to a range of clinical studies where we study currently licensed pertussis vaccines. This will help us develop a comprehensive immunological knowledge base that we can use to develop and evaluate novel formulations. At the same time, we are developing clinical and laboratory capacity for such studies. Since this is such a big endeavor, this effort can really only succeed through collaboration between clinical partners, researchers, public health authorities and vaccine manufacturers. Hopefully, in a few years this will lead to even better pertussis vaccines.

Reference:

Diavatopoulos D. Road towards effective control of pertussis: challenges and opportunities. Paper presented at: World Vaccine Congress Europe; October 29-31, 2018; Lisbon, Portugal. https://www.terrapinn.com/conference/world-vaccine-congress-europe/speaker-dimitri-DIAVATOPOULOS.stm. Accessed October 24, 2018.