Epidemiology of acute respiratory infections in Spain during the 2024-2025 season
DOI:
https://doi.org/10.4321/s2173-92772026000200006Keywords:
acute respiratory infection; severe acute respiratory infection; influenza; COVID-19; RSV; surveillanceAbstract
Introduction: The Acute Respiratory Infection Surveillance System (SiVIRA) provides integrated monitoring of acute respiratory infections, particularly those caused by influenza, SARS-CoV-2 and respiratory syncytial virus (RSV). This work presents the results for the 2024-25 season.
Method: All cases that attended primary care for acute respiratory infection (ARI) or were admitted for severe ARI (SARI) were collected, and weekly incidence rates were calculated, weighted by age, sex and autonomous community. A representative sample was selected for microbiological study, and the percentage of positivity to influenza, SARS-CoV-2 and RSV was calculated.
Results: ARI and SARI rates peaked between weeks 02/2025 and 04/2025, with 803 cases/100,000 inhabitants and 24.2 hospitalizations/100,000 inhabitants, respectively. The influenza epidemic developed between weeks 50/2024 and 09/2025, peaking in week 04/2025. Type A predominated (57% of ARI cases and 90% of hospitalizations). COVID-19 changed its temporal pattern, with no epidemic wave in autumn-winter but a preserved spring-summer wave, peaking in week 38/2025. The BA.2.86 variant initially predominated, followed by XFG, which began to circulate from week 16/2025. RSV circulation started in week 46/2024 with ARI cases peaking in week 51/2024 and hospitalizations in week 01/2025.
Discussion: In the 2024-25 season, the circulation of influenza, SARS-CoV-2 and RSV was more staggered, with no winter wave of COVID-19. This resulted in lower weekly rates of acute respiratory infection and hospitalization than in previous seasons.
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Copyright (c) 2026 Jorge Franco Herrero, Marcos Lozano-Álvarez, Ana María Puerto, Francisco Pozo, Sonia Vázquez-Morón, María Iglesias-Caballero, Carolina Wu Kohatsu, Inmaculada Casas, Susana Monge, Grupo SiVIRA, RELECOV
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