Sentinel Surveillance of Severe Acute Respiratory Infections in Serbia in 2022-2023 Season

INTRODUCTION: Sentinel surveillance of severe acute respiratory infections (SARI) was implemented in Serbia in November 2009. Nine sentinel hospitals in 3 cities participated in the integrated SARI surveillance system. Four of them are children's hospitals. The aim of this study is to provide a review of integrated sentinel surveillance of SARI in Serbia in 2022-2023 influenza season, from October 2022 to April 2023. METHODS: Integrated Sentinel Surveillance of SARI has been done in accordance with professional guidance for epidemiological surveillance of influenza. Both epidemiological and virological data were collected on a weekly basis. All specimens were tested for influenza, SARS-CoV-2 and Respiratory syncytial virus (RSV). Intensive care units (ICUs), pediatric and respiratory disease wards were all represented. For laboratory confirmation, Real time polymerase chain reaction (RT-PCR) was used. RESULTS: Start of influenza season was registered in week 44/2022. A total of 3027 SARI cases were reported with 100% recorded age. Of these, 14% were 0-4 years old, 9% were 5-14, 7% were 15-29, 38% were 30-64 and 32% were ≥65. Among these cases, 607(20%) respiratory specimens were collected during the surveillance period. The number of positive samples for influenza was 208(34%), for SARS-CoV-2 was 37(6%) and for RSV 12(2%). The highest proportion of laboratory-confirmed influenza cases was 58% in week 51/2022. then, above 50% in week 7/2023 and 8/2023. All three influenza viruses were confirmed: A(H1)pdm09, A(H3) and type B. B viruses predominated, accounting for 38% of all sentinel SARI detections. There no were death associated to influenza, SARS-CoV-2 and RSV. CONCLUSIONS: Integration epidemiological with laboratory surveillance as well as integrated sentinel SARI surveillance for influenza, SARS -CoV-2 and RSV highlights the importance of maintaining and improving national influenza surveillance capacity especially in the frame of International Health Regulations. KEY MESSAGES: • Quality, representativeness and sustainability are the guiding principles for integrated, SARS-CoV-2, RSV and influenza sentinel SARI surveillance. • The threat of influenza remains, and it is essential for countries to be vigilant for the emergence of non seasonal influenza viruses of pandemic potential and prepare for the next influenza season.