On 5 and 6 October, the 23rd annual meeting of the EUPertStrain network was held at Vall d'Hebron. The aim of the network is to improve whooping cough surveillance and to study the impact of changes in Bordetella pertussis, the bacterium responsible for this disease, on the effectiveness of vaccines in European countries. Throughout the two days, participants presented their latest studies on B. pertussis and pertussis. On this occasion, the conference was organised by Dr. Juanjo González, head of the Microbiology research group at Vall d'Hebron Institute of Research (VHIR), Dr. Alba Mir, researcher of the same group, as well as Professor Qiushui He and Dr. Alex Barkoff from the University of Turku (Finland), and was attended by more than 40 professionals and academic researchers experts in the fields of clinical microbiology and public health.

Pertussis is a highly contagious immuno-preventable respiratory disease with high morbidity and mortality caused by B. pertussis whose initial symptoms are mild, such as runny nose, fever or cough, which may persist for weeks or months. In Spain, more than 90% of the population is vaccinated, which favours the control of the disease, but in the case of newborns and infants under two months of age who have not yet received the vaccine, pertussis can be particularly severe and lead to significant sequelae and even death.

The European Union network for epidemiological surveillance and control of vaccine-preventable infections estimates that around 40,000 cases of pertussis are reported annually in Europe, with an overall incidence of 8.2 cases per 100,000 population. Infants under one year of age, who have not completed the primary pertussis vaccination series due to their young age, are the most affected age group with the highest incidence rate (44.4 cases per 100,000 population), followed by children aged 10-14 years.

Although the prevalence of the disease is cyclical, an increase in pertussis cases has been observed in recent years. "Among the causes of this increase is the adaptation of the microorganism, so that it can evade the immune response induced by vaccination. This is why we must continue research to understand the evolution of the microorganism and adapt vaccines to achieve better protection of the population", says Dr. Juanjo González.

Over the course of the two days, up to 16 studies were presented in four different areas: Diagnostics and Typing, Immunology and Vaccines, Biology and Evolution of B. pertussis, and Epidemiology. Among the most outstanding projects is the characterisation of B. pertussis over the years, in order to understand its evolution and adaptation to vaccines. In addition, the beneficial effects of vaccination in pregnant women for the protection of newborns have also been presented.

Diagnosis of pertussis was another focus of the conference, as early detection is essential to avoid serious complications in the most vulnerable patients and to prevent human-to-human transmission of the disease. New tools are being developed to facilitate rapid diagnosis at the first signs of infection.

Another important aspect addressed during the meeting was the design of new, more effective vaccines with the capacity to confer more lasting protection against the acquisition of the disease. In this sense, several papers have shown the advances in the identification of new vaccine antigens, as well as new vaccination strategies such as those based on intranasal administration of vaccines.

The meeting also served as a venue for the creation of a working group to develop the multi-centre project EUPertStrain V. This study aims to analyse the changes that have occurred in B. pertussis populations circulating in Europe over the last 20 years in order to identify how different changes in vaccination systems may be conditioning the adaptation and vaccine escape of the microorganism, as well as to detect the emergence of strains resistant to the antibiotics used to treat the infection.

EuPertStrain

The European EUPertStrain network was established in 2001 and consists of national reference laboratories and research laboratories in Europe. Its members have published various expert consensus articles on pertussis diagnosis by PCR and serology, and epidemiological typing of B. pertussis and provides an important platform for the exchange of information in the field of pertussis at European level. The group, of which VHIR is a member, is coordinated by the Finnish National Reference Laboratory for Pertussis and Diphtheria at the University of Turku, Finland.

The Microbiology research group at VHIR works on the study of emerging and re-emerging infectious diseases, as well as vaccine-preventable infections such as pertussis, invasive meningococcal disease, influenza or COVID-19, among others. In the case of pertussis, the group studies the evolution and adaptation of B. pertussis in Catalonia and Spain and the dispersal capacity of the different variants of the microorganism in order to identify new strategies to prevent the acquisition of the disease and to identify new antigens that could be future candidates for the design of new vaccines.