Epidemiological characteristics of acute respiratory infectious diseases in the first year after COVID-19 pandemic in Guangdong Province, China

Abstract

Background: Acute respiratory infections are caused by a diverse range of pathogens. The study aims to elucidate the epidemic characteristics of acute respiratory pathogens in Guangdong Province during the first year after the COVID-19 pandemic. Methods: We collected sentinel surveillance data of 12 respiratory pathogens from multi-pathogen surveillance among acute respiratory infections from August 2023 to July 2024 in Guangdong Province, China. We also collected surveillance data on hospitalized pneumonia as a supplementary. We calculated the test positivity for each pathogen and performed pairwise correlation analysis. Results: Multi-pathogen surveillance revealed that over half of acute respiratory infections tested positive for at least one pathogen. The most commonly detected pathogens were influenza virus (19.70%, 3,211/16,296), Streptococcus pneumoniae (10.99%, 1,343/12,215), and rhinovirus/enteroviruses (8.66%, 1,411/16,296). In the autumn and winter of 2023, the test positivity of influenza virus surpassed 20% starting in October, indicating that the winter epidemic period arrived earlier than that in the pre-COVID-19 pandemic period (typically December or later). The overall positivity was highest in the 0–14 age group (60.07%, 4,797/7,903), and pathogen distribution varied significantly across age groups. Correlation analysis revealed significant positive correlations between rhinovirus/enteroviruses and other pathogens, such as respiratory syncytial virus. Hospitalized pneumonia surveillance showed the proportion of Mycoplasma pneumoniae infections increased to 17.08% (3,707/21,701) in 2023, surpassing the pre-pandemic average of 10.52%. Conclusions: After the COVID-19 pandemic, we observed different characterization of the pathogen causing acute respiratory infections in Guangdong Province. The activity of influenza and Mycoplasma pneumoniae initially exhibited shifts compared to the pre-pandemic period. Pathogen distribution varied significantly across age groups, highlighting high-risk populations for specific pathogens. Continuous multi-pathogen surveillance is essential for understanding their epidemiological characteristics and formulating effective prevention and control measures, including vaccination strategies, clinical interventions.