Changes in the epidemic patterns of respiratory pathogens of children in guangzhou, China during the COVID-19 pandemic

Abstract

Objective: To investigate the epidemiological characteristics of pediatric respiratory pathogens in Guangzhou, China, from 2018 to 2023 in the context of the COVID-19 Pandemic and to evaluate the impact of non-pharmaceutical interventions (NPIs) on the transmission dynamics and seasonal patterns of respiratory pathogens.

Methods: A retrospective analysis was conducted at Guangzhou Women and Children's Medical Center between January 2018 and December 2023. Pediatric patients who underwent the respiratory pathogens tests were enrolled in the study and divided into four groups by age: Infant group, Toddler group, Preschool group, and School-age group. The nasopharyngeal swab or bronchoalveolar lavage fluid (BALF) samples were collected for real-time fluorescence quantitative polymerase chain reaction (qPCR) test of respiratory pathogens. Ten common respiratory pathogens, including respiratory syncytial virus (RSV), Mycoplasma pneumoniae (MP) and Influenza A virus (FluA), were detected. In addition, the study period was divided into three phases: Pre-COVID-19 (2018-2019), COVID-19 (2020-2022), and Post-COVID-19 (2023). Detection rates, distribution patterns, and seasonal variations of respiratory pathogens were analyzed between different phases and different age groups.

Results: This study included 317,828 pediatric patients (median age: 3.4 years, IQR: 1.3-6.0), from whom 1,160,764 respiratory pathogen tests were conducted. The overall pathogen detection rate was 8.02% (93,108/1,160,764). The positive rate during the COVID-19 phase (18.44%, 95% CI 14.89-22.00%) was significantly lower than that of the Pre-COVID-19 (27.55%, 95% CI 23.95-31.16%) and Post-COVID-19 (27.15, 95% CI 21.47-32.84%) phases (P < 0.001). No significant difference was observed between Pre-COVID-19 and Post-COVID-19 phases (P = 0.948). Different pathogens exhibited varying levels of suppression and recovery patterns, with some demonstrating altered seasonal patterns. The primary affected age groups shifted from infants and toddlers during the Pre-COVID-19 and COVID-19 phases to preschool and school-age children in the Post-COVID-19 phase. Co-infections were identified in 2,515 cases, with the highest rate observed during the Pre-COVID-19 phase (3.40%), followed by the COVID-19 (2.26%) and Post-COVID-19 (2.46%) phases.

Conclusions: NPIs implemented during the early COVID-19 pandemic effectively suppressed the transmission of respiratory pathogens and disrupted their seasonal patterns. However, some pathogens gradually resumed activity during the mid-to-late COVID-19 phase, leading to atypical outbreaks. Following NPI relaxation, multiple pathogens rebounded during the Post-COVID-19 phase, posing significant challenges for the healthcare system. These findings offer valuable insights for guiding public health strategies and optimizing the prevention and control of respiratory infections.

Clinical trial number: Not applicable.

Keywords: COVID-19; Children; Epidemiological characteristics; Non-Pharmaceutical interventions; Respiratory pathogens.

Fig. 1

Annual Age Distribution of Pediatric Patients Undergoing Respiratory Pathogen Testing in 2018–2023. Stacked bar chart showing the annual number and proportion of enrolled patients in four defined age groups (Infant: <1 year; Toddler: ≥1 and < 4 years; Preschool: ≥4 and < 6 years; School-age: ≥6 and < 18 years)

Fig. 2

Monthly Trends of Overall Positive Respiratory Pathogen Cases and Detection Rates in 2018–2023. Bar chart (left Y-axis) shows monthly positive cases, color-coded by phase (Pre-COVID-19 (2018–2019), COVID-19 (2020–2022), Post-COVID-19 (2023) ); red line (right Y-axis) indicates monthly positive detection rate. Pathogen activity sharply decreased in early 2020, followed by suppressed/altered seasonality, and a marked resurgence in 2023

Fig. 3

Monthly Trends in Detection Rates (A) and Positive Cases (B) for Ten Individual Respiratory Pathogens in 2018–2023. (A) Heatmap of monthly positive detection rates (%) for each pathogen. (B) Stacked area plot of monthly positive cases by pathogen, showing relative contributions. Most pathogens exhibited suppression during the COVID-19 phase, with notable resurgences for RSV, MP, FluA, and FluB in later periods. RSV: Respiratory syncytial virus; MP: Mycoplasma pneumoniae; HAdV: Human adenovirus; FluA: Influenza A virus; FluB: Influenza B virus; CP: Chlamydia pneumoniae; HPIV: Human parainfluenza virus; HBoV: Human bocavirus; HMPV: Human metapneumovirus; HRV: Human rhinovirus

Fig. 4

Annual Positive Respiratory Pathogen Cases (A) and Detection Rates (B) by Age Group in 2018–2023. Age groups are defined as: Infant (< 1 year), Toddler (≥ 1 to < 4 years), Preschool (≥ 4 to < 6 years), School-age (≥ 6 to < 18 years). (A) Bar chart of annual positive cases by age group. (B) Line graph of annual detection rates by age group (calculated as: Positive Cases in Age Group for that year / Total Enrolled Patients in Age Group for that year × 100%). While rates initially declined across all age groups, a rebound occurred with infections becoming most prevalent in preschool and school-age children in 2023

Fig. 5

Annual Detection Rates of Specific Respiratory Pathogens by Age Group in 2018–2023. Age groups are defined as in Fig. 4. (A) Heatmap displaying annual detection rates (%) for ten respiratory pathogens by age group and year (darker color representing higher rates). (B) Bubble charts showing annual detection rates (%) for the top 5 predominant pathogens in each age group; bubble size and color intensity (e.g., darker red) indicate higher rates (empty spaces: pathogen not in top 5 for that age/year). Distinct age-related pathogen susceptibilities (e.g., RSV in infants; MP, FluA in older children) and temporal shifts in these patterns were evident