Increase of pertussis cases in the EU/EEA

Epidemiological situation

Pertussis is an endemic disease in the EU/EEA and worldwide. Every three to five years, larger epidemics are expected even with high vaccination coverge.

After a few years of limited circulation in the EU/EEA, particularly during the COVID-19 pandemic, more than 25 000 cases of pertussis were reported in 2023, and more than 32 000 between January and March 2024. Similar numbers were observed in 2016 (41 026) and 2019 (34 468).

During 2023-24, in 17 EU/EEA countries, infants (those under the age of one year) represented the group with the highest reported incidence, whereas in six countries, the highest incidence is reported in adolescents 10-19 years. The majority of deaths occurred in infants. These surveillance data need to be interpreted with caution due to known differences in Member State surveillance systems, availability of laboratory methods, testing practices, as well as vaccination schedules. Furthermore, case ascertainment can vary by age group. In many countries, maternal vaccination programmes are used to protect infants in the first months of life. However coverage data, where available for such programmes, appears to be sub-optimal.

The observed epidemiological picture can be ascribed to a number of factors, which include: expected epidemic peaks, presence of unvaccinated or not up to date vaccinated individuals, waning immunity, decreased contribution of natural boosting in the overall population during the COVID-19 pandemic period.

Risk assessment

The risk from pertussis was assessed for four different population groups as a product of the probability of infection and its impact. The overall risk is assessed as high for unimmunised or partially immunised infants<6 months of age, as they represent the group with the highest morbidity and mortality from pertussis.

Infants >6 months and children up to 15 years of age have a moderate risk if they are unimmunised or partially immunised and have a low risk if they are fully vaccinated according to national immunisation schedules.

Older adolescents >16 years and adults up to 64 years of age have a moderate risk which is reduced to low if they have recently received a booster dose.

Finally, older adults (≥65 years of age) and persons of any age with underlying conditions such as asthma, chronic obstructive pulmonary disease (COPD) or immunosuppression, have an overall moderate risk from pertussis, having a moderate probability of infection and moderate impact (i.e. a higher probability of experiencing severe illness than individuals in the younger age/group).
 

Recommendations

The primary objective of national pertussis immunisation programmes in EU/EEA countries should be to curb morbidity and mortality in newborn infants. To this end, and in view of the ongoing pertussis outbreaks, ECDC encourages EU/EEA public health authorities to focus on the following areas:

• Achieve and sustain high vaccination coverage through timely and full completion of pertussis primary immunisation series and subsequent boosters recommended nationally.
• In addition to the routine programme, maternal immunisation is a highly effective approach to prevent disease and death in young infants. There is a need to bolster interventions to improve access and implementation of childhood and maternal immunisation policies. Review and, if needed, upgrade of immunisation information systems will enable a follow-up of vaccination status across different providers and life stages to strategically inform vaccination programmes.
• Increase the awareness of health professionals about the epidemiological situation of pertussis in their geographical area, the clinical presentation of pertussis, and prevention through vaccination: if needed, develop protocols for the management of cases with protracted cough and laboratory confirmed pertussis. Pertussis can occur in persons of all ages with varying clinical picture, and clinical suspicion is often low. If needed, testing options should be outlined for the confirmation of the disease.
• Continue surveillance of pertussis and ensure public health capacity for early detection, diagnosis, response to and control of outbreaks, including appropriate contact tracing around the cases to protect close contacts at risk of severe disease. Monitoring and reporting of B. pertussis resistance to macrolides is important.
• Employ risk communication on the disease and the importance of vaccination, and strategies to promote vaccine acceptance and uptake. Information on pertussis should stress that this is a highly transmissible disease, and there is a need to protect infants. Healthcare providers’ recommendations are very important for uptake of maternal vaccination, in countries that have such programmes, and for timely completion of the primary immunisation series and boosters. Factors that affect acceptance of the pertussis vaccine should be explored.