Background: The Covid-19 pandemic has significantly disrupted the epidemiology of acute respiratory infections (ARI), leading to a decrease from other respiratory pathogens. It is important to investigate the trends of ARI following Covid-19 pandemic. Objective: This study aims to record and analyze the epidemiological situation of ARI in Huzhou, Zhejiang, China, after Covid-19 pandemic. Methods: A retrospective study was conducted using PCR testing data for respiratory infection pathogens from febrile patients at Huzhou Central Hospital from June 1, 2024, to April 30, 2025. Results: Among a total of 34,893 patients with fever, 16,643 (47.7%) males and 18,250 (52.3%) females, the total number of conformed ARI cases was 17,750 (50.9%), of which 2,897 (16.3%) cases were infected with SARS-COV-2, 5,592 (31.5%) with Influenza A Virus (IAV), 40 (0.2%) with Influenza B Virus (IBV), 701 (3.9%) with Respiratory Syncytial Virus (RSV), 3,205 (18.1%) with Adenovirus (ADV), 3,737 (21.1%) with Human Rhinovirus (HRV), and 1,578 (8.9%) with Mycoplasma Pneumoniae (MP). An outbreak of SARS-CoV-2 infection was found from June 30 to August 3, 2004, and two outbreaks of IAV occurred from December 21, 2024, to January 18, 2025, and from February 9 to March 1, 2025. In terms of age distribution, SARS-CoV-2 and IAV infections peaked in children (£12 years), while multiple peaks appeared in adults (³13 years); RSV, ADV, HRV and MP infections were focused on patients aged £12 years. There were 1530 cases (8.9% of pathogen-positive cases) with co-infections of 2, 3 or 4 pathogens, including 856 cases with co-infection of ADV and HRV, 172 of IAV and HRV, and 134 of HRV and MP. In the last week of April 2025, the number of COVID-19 patients increased to 100. Conclusion: In the second and third years following Covid-19 pandemic, acute respiratory infections caused by RSV, ADV, HRV and MP continued to occur weekly, but outbreaks of SARS-CoV-2 and IAV have been observed in the past 11 months. A new outbreak of COVID-19 may occur in May.

COVID-19, Epidemiology, Acute Respiratory Infection (ARI), Influenza A (IAV)