Background This study was initiated to evaluate, for the first time, the performance and quality of the influenza-like illness (ILI) surveillance system in Tunisia. Methods The evaluation covered the period of 2012 – 2015 and used different data sources to measure indicators related to data quality and completeness, representativeness, timeliness, simplicity, acceptability, flexibility, stability and utility. Results During the evaluation period, 485.221 ILI cases were reported among 6.386.621 outpatients at 268 ILI sentinel sites. To conserve resources, cases were only enrolled and tested for influenza during times when the number of patients meeting the ILI case definition exceeded 7% (10% after 2014) of the total number of outpatients for the week. When this benchmark was met, five to 10 patients were enrolled and sampled by nasopharyngeal swabs the following week. In total, The National Influenza Center (NIC) received 2476 samples, of which 683 (27.6%) were positive for influenza. The greatest strength of the system was its representativeness and flexibility. The timeliness of the data and the acceptability of the surveillance system performed moderately well; however, the utility of the data and the stability and simplicity of the surveillance system need improvement. Overall, the performance of the Tunisian influenza surveillance system was evaluated as performing moderately well for situational awareness in the country and for collecting representative influenza virologic samples. Conclusions The influenza surveillance system in Tunisia provided pertinent evidence for public health interventions related to influenza situational awareness. To better monitor influenza, we propose that ILI surveillance should be limited to sites that are currently performing well and the quality of data collected should be closely monitored and improved.

The burden of influenza was estimated from surveillance data in Tunisia using epidemiological parameters of transmission with WHO classical tools and mathematical modelling. The incidence rates of influenza-associated influenza-like illness (ILI) per 100 000 were 18 735 in 2012/2013 season; 5536 in 2013/14 and 12 602 in 2014/15. The estimated proportions of influenza-associated ILI in the total outpatient load were 3.16%; 0.86% and 1.98% in the 3 seasons respectively. Distribution of influenza viruses among positive patients was: A(H3N2) 15.5%; A(H1N1)pdm2009 39.2%; and B virus 45.3% in 2014/2015 season. From the estimated numbers of symptomatic cases, we estimated that the critical proportions of the population that should be vaccinated were 15%, 4% and 10% respectively. Running the model for the different values of R0, we quantified the number of symptomatic clinical cases, the clinical attack rates, the symptomatic clinical attack rates and the number of deaths. More realistic versions of this model and improved estimates of parameters from surveillance data will strengthen the estimation of the burden of influenza. Modélisation de la grippe saisonnière et estimation de sa charge en TunisieRÉSUMÉ En Tunisie, la charge de la grippe a été estimée à partir des données de surveillance, en utilisant les paramètres épidémiologiques de la transmission avec les outils classiques de l'OMS et la modélisation mathématique. Les taux d'incidence des syndromes de type grippal (STG) associés à la grippe étaient 18 735 pour 100 000 pour la saison 2012-2013 ; 5 536 pour 2013-2014 et 12 602 pour 2014-2015. La part estimée de STG associés à la grippe pour la charge totale de patients externes était respectivement de 3,16 %, 0,86 % et 1,98 % pour les trois saisons. Parmi les patients positifs au virus de la grippe, la répartition était la suivante pour la saison 2014-2015 : 15,5 % pour le virus A(H3N2) ; 39,2 % pour le virus A(H1N1)pdm2009 ; et 45,3 % pour le virus B. À partir du nombre estimé de cas symptomatiques, nous avons calculé que la proportion critique de la population devant être vaccinée était respectivement de 15 %, 4 % et 10 %. L'exécution du modèle avec les différentes valeurs de R0 nous a permis de déterminer le nombre de cas cliniques symptomatiques, les taux d'attaque clinique, les taux d'attaque clinique pour les cas symptomatiques et le nombre de décès. Des versions plus réalistes de ce modèle ainsi que des estimations améliorées des paramètres issus des données de surveillance permettront d'accroître l'utilité des modèles mathématiques.

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Background The influenza vaccine (IV) is considered the most effective strategy to prevent seasonal influenza infection and annual vaccination of healthcare workers (HCWs) is recommended by the World Health Organization given their high mixing with patients. We assessed IV uptake among HCWs in the 2018–2019 season and explored their knowledge and attitudes regarding influenza immunization. Methods A cross-sectional study was conducted in 150 representative Tunisian health facilities from March to May 2019. We recruited 1231 HCWs with direct patient contact using self-weighted multistage sampling. Univariate and multivariate logistic regression analyses permitted to assess the factors associated with IV uptake in the 2018–2019 influenza season. Results Among 1231 health professionals enrolled in this study, less than half (36.6, 95% confidence interval [CI]: 33.9–39.4) received the IV at least once in their lives and only 15.3% (CI: 13.3–17.4) were vaccinated against influenza in the 2018–2019 influenza season. High confidence regarding IV efficacy, belief about the mandatory character of influenza vaccination for HCWs, and IV uptake in the 4 years preceding the 2018–2019 influenza season were independently associated with higher IV uptake by multivariate analysis. However, participants with high educational level were less likely to receive the IV than those with the lowest educational level. Conclusions Our study revealed a low vaccination rate among Tunisian HCWs confirming the importance of tailored education programs targeting this population.

Background Generally, seasonal influenza does not cause severe infection in healthy adults, but for the elderly, an infection can pose a serious health concern. Although several measures can help prevent influenza, vaccination is considered the most effective. This study aimed to assess influenza vaccine uptake among elderly with chronic diseases in Tunisia during the 2018–2019 influenza season, and to identify knowledge, attitudes and barriers associated with influenza vaccine uptake. Methods During influenza season of 2018–2019, we conducted a national cross-sectional study among elderly with chronic disease who were attending primary and secondary health care facilities in Tunisia. We collected data regarding practices, general knowledge and attitudes related to influenza and influenza vaccine, using a standardized questionnaire. A multivariate analysis by logistic regression was performed to assess the factors influencing willingness to receive influenza vaccine. Results Among the 1191 surveyed elderly, 19.4% (95%CI 14.1–21.9) were vaccinated during the 2018–2019 influenza season and 64.7% (61.9–67.3) expressed willingness to be vaccinated in the next season regardless of vaccination status in the 2018–2019 season. Previous vaccination in the 2018–2019 influenza season was the most significantly associated factor with willingness to receive influenza vaccine (adjusted OR = 16.5 [3.7–72.4]). Significant associations were also observed between knowledge of influenza severity for the elderly as well as for those with chronic diseases and willingness to be vaccinated (p < 0.01). Likewise, participants who were convinced by flu vaccine effectiveness and those who were not concerned about vaccine side effects were more likely to be vaccinated (p < 0.001). The main reason that may lead to vaccine acceptance was a doctor’s recommendation (41.1%), while the two main reasons that may lead to vaccine refusal were concerns about side effects (71.5%) and a belief that vaccine was ineffective in averting influenza illness (33.9%). Doctors were the most trusted source for information about influenza vaccine (91.5%). Conclusion Our study revealed low influenza vaccination coverage among Tunisian elderly with chronic diseases believed to be at higher risk for severe acute respiratory infections and death if infected with influenza. Treating physicians’ role in promoting influenza vaccination in this high-risk group seems to be crucial.

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Seroprevalence studies are essential to get an accurate estimate of the actual SARS-CoV-2 diffusion within populations. We report on the findings of the first serosurvey conducted in Tunis prior to the implementation of mass vaccination and analyzed factors associated with seropositivity. A household cross sectional survey was conducted (March–April 2021) in Tunis, spanning the end of the second wave and the beginning of the third wave of COVID-19. SARS-CoV-2 specific immunoglobulin G (IgG) antibodies to the spike (S-RBD) or the nucleocapsid (N) proteins were detected by in-house ELISA tests. The survey included 1676 individuals from 431 households. The mean age and sex ratio were 43.3 ± 20.9 years and 0.6, respectively. The weighted seroprevalence of anti-N and/or anti-S-RBD IgG antibodies was equal to 38.0% (34.6–41.5). In multivariate analysis, age under 10, no tobacco use, previous diagnosis of COVID-19, a history of COVID-19 related symptoms and contact with a COVID-19 case within the household, were independently associated with higher SARS-CoV-2 seroprevalence. More than one third of people living in Tunis obtained antibodies to SARS-CoV-2. Further studies are needed to monitor changes in these figures as Tunisian population is confronted to the subsequent epidemic waves and to guide the vaccine strategy.