Evolution of influenza and acute respiratory infections in the Republic of Moldova during the 2014/15-2022/23 seasons

Abstract

Introduction. Influenza-like illness (ILI), Acute Respiratory Infections (ARI), and Severe Acute Respiratory Infections (SARI) are the most common infectious diseases globally, causing severe forms annually, especially in at-risk groups. The aim of this paper is to analyse the epidemiological and virological data on ILI, ARI, and SARI in the Republic of Moldova during the 2014/2015 to 2022/2023 epidemic seasons. Material and methods. The descriptive-retrospective epidemiological study analysed morbidity due to ILI, ARI, and SARI, as well as laboratory results for the presence of influenza viruses during the 2014/2015 to 2022/2023 epidemic seasons. Results. ILI has been of low to medium intensity except for two seasons, while ARI has been of very high intensity in one season. ILI, ARI, and SARI primarily affected children aged 0-14 years. During the nine seasons (except 2020/2021), influenza virus types A(H1N1) pdm09, A(H3N2), and B have been identified, with the percentage of positives decreasing considerably in the last two seasons. During the period under review, each influenza virus type dominated, and in three seasons, two to three virus types co-dominated. Genetic characterization of the identified strains demonstrated that influenza viruses fully fit the phylogenetic tree constructed for the nominated period, do not differ antigenically from strains identified in other regions of the northern hemisphere, and are susceptible to antivirals. Conclusions. The national surveillance system for ILI, ARI, and SARI makes it possible to monitor the evolution of the epidemic process in real-time and geographic space, facilitating prompt intervention with control and response measures.

Keywords

• influenza
• acute respiratory infections
• severe acute respiratory infections