Epidemiological features of pertussis in Tunisia, 2009-2023

Abstract Background Despite the introduction of pertussis vaccines as part of most immunization programs worldwide, epidemiological data indicate that this disease remains an important public health concern. In Tunisia, pertussis is a mandatory notifiable disease with a vaccination coverage (with three doses) estimated to 92% (2023). We aimed to describe the epidemiological features of pertussis in Tunisia during the period 2009-2023. Methods Descriptive study, based on data from the national Mandatory Reporting System (MRS), was conducted. All notification forms related to pertussis cases that had occurred between 2009 and 2023, were included. To calculate the disease crude incidence rate, the population size was obtained from the national institute of statistics estimations. Data entry and analysis was performed with (SPSS version 23.0) software. Results Over the study period, a total of 751 pertussis cases were collected. The disease's epidemiology follows a cyclic trend every 3 to 5 years, and the year 2023 marked the highest registered incidence rate estimated to 1.25 cases per 100 000 inhabitants with 149 cases. In 2023, (26.1%) of cases were among infants under two months of age who had not received vaccination; and (48.6%) of cases were among infants aged between two and six months with incomplete vaccination. The median delay between lab confirmation and notification as part of the MRS was 1 day, IQR (0.25-2). Most of cases were reported from laboratories (40.9%), university hospitals (20.9%) and private healthcare facilities (12.1%). Conclusions Our study highlighted the fact that pertussis remains a public health threat in the Tunisian context, despite a good vaccination coverage. Thus, adjustment decisions to the current vaccination strategy have been made, notably with the introduction of the acellular pertussis vaccine for pregnant women. Key messages • Pertussis remains a serious public health concern in Tunisia, and during the last two decades, the highest incidence rate was registered in 2023 (1.25 / 100 000). • The adjustment of the current vaccination strategy with the introduction of the acellular pertussis vaccine for pregnant women, is crucial.