Lucas Felipe Kist

Objective: To describe the epidemiological, clinical, and seasonal patterns of respiratory viral infections in Southern Brazil between January 2023 and April 2026. Methods: A retrospective observational descriptive study was conducted at a private hospital including laboratory-confirmed cases of SARS-CoV-2, influenza A (H3N2 and H1N1), respiratory syncytial virus (RSV A and B), rhinovirus, adenovirus, metapneumovirus, enterovirus, bocavirus, parainfluenza viruses, and seasonal coronaviruses. Respiratory pathogens were detected using molecular testing (XGEN MULTI PR24 FLOW CHIP) or rapid antigen detection tests. Demographic, clinical, and temporal data were analyzed according to age group. Results: A total of 18,214 detections were identified. Influenza A was the most frequent pathogen (48.08%), followed by SARS-CoV-2 (23.73%) and RSV A (8.65%). Hospitalization occurred in 20.44% of patients, 21.11% of hospitalized individuals required intensive care, and 2.93% required mechanical ventilation. Adults showed alternating seasonal peaks of influenza A and SARS-CoV-2, with influenza A predominating during colder seasons and SARS-CoV-2 during warmer periods. In children, SARS-CoV-2 incidence was lower, whereas RSV A and other respiratory viruses showed greater circulation. Declines in influenza A and COVID-19 detections were observed during periods that temporally overlapped with national vaccination campaigns; however, vaccination coverage was not assessed in this study. Conclusions: Respiratory viral infections remained frequent in the post-pandemic period, reinforcing the importance of continuous surveillance, seasonal monitoring, and vaccination strategies.

Dengue virus (DENV) remains a major global public health challenge, driven by the expanding distribution of Aedes vectors, rapid urbanization, and increasing climate variability. This review aimed to synthesize current evidence on dengue transmission dynamics, immunopathogenesis, molecular epidemiology, diagnostic and therapeutic advances, vaccine development, and the influence of climatic factors on disease patterns. A comprehensive search of major electronic databases was conducted to identify relevant literature, followed by a qualitative synthesis of the evidence. The evidence highlights complex transmission cycles involving Aedes aegypti and Aedes albopictus, with transmission strongly influenced by temperature, humidity, rainfall, and extreme climate events. Advances in immunopathogenesis research have improved understanding of mechanisms associated with severe disease, including antibody-dependent enhancement and dysregulated inflammatory responses. Diagnostic innovations, such as reverse transcription polymerase chain reaction (RT-PCR), NS1 antigen detection, and point-of-care technologies, have enhanced case identification, while prevention strategies increasingly incorporate integrated vector management, digital surveillance systems, and emerging vaccines. Integrating epidemiological, molecular, and climatic information may strengthen early warning systems, improve outbreak prediction, and support more effective dengue prevention and control strategies.