Pediatric respiratory infection patterns shift after COVID-19 pandemic

Respiratory infection trends in children have significantly shifted following the COVID-19 pandemic, according to a recent study published in Pediatric Investigation.¹

Concurrent circulation of viruses and atypical bacteria is often reported in children, altering disease patterns in ways that may be difficult to predict. Additionally, understanding of these interactions has changed following the COVID-19 pandemic and associated use of masks, school closures, and reduced social contact.

“This was a rare opportunity to observe how respiratory pathogens behave when their normal transmission patterns are disrupted, then suddenly restored,” said Hailin Zhang, MD, researcher from The Second Affiliated Hospital. “The pandemic allowed us to see not only the changes in infection rates, but also how pathogens influence one another.”

Pathogen testing and detection methods

The retrospective study was conducted to evaluate interactions between non-bacterial respiratory pathogens during and after the COVID-19 pandemic.² Participants included children hospitalized with acute respiratory tract infections.

These patients received routine testing for non-bacterial respiratory pathogens, with clinically standardized protocols followed to obtain sputum or nasopharyngeal samples. Afterward, samples underwent polymerase chain reaction-capillary electrophoresis fragment analysis for the following pathogens:

• Influenza A virus (Inf A)
• H1N1
• Influenza B virus (Inf B)
• Human parainfluenza virus (HPIV)
• Human RSV (HRSV)
• Human adenovirus (HAdV)
• Human rhinovirus (HRV)
• Human metapneumovirus (HMPV)
• Bocavirus
• Coronavirus
• Chlamydia
• M. pneumoniae

Pathogen prevalence and coinfections

There were 73,098 pediatric patients included in the final analysis. A pathogen was detected in 65.18% of this population, with 11.97% having multiple pathogens. The most common pathogen was M. pneumoniae in 15.97% of patients, while the most common virus was HRV in 11.28%.

Additional common viruses included HRSV in 7.46% of patients, HMPV in 3.72%, HAdV in 3.56%, and HPV in 3.30%. The most common coinfection was HRV and M. pneumoniae, reported in 2.60% of patients. HRV and HRSV was indicated as the most common vital coinfections with a rate of 0.87%.

Weekly detection rates of respiratory pathogens ranged from 19.21% to 82.83%. In the spring, H1N1 and HRV were the most common pathogens, vs HRSV and coronavirus in the summer, M. pneumoniae, bocavirus, HPIV, and H3N2 in autumn, and Inf B, HMPV, and HAdV in winter.

Post-pandemic phases and changing infection patterns

Phase 2 of the analysis, defined as the 51^st week of 2022 to the 14^th week of 2023, was accompanied by a significant upward trend of H1N1 influenza infections. Other viruses underwent significant declines in the detection rates during this time, except for H3N2 influenza and HAdV which remained similar to Phase 1.

A significant increase in M. pneumoniae was reported in the final phase of the analysis, which began the 15^th week of 2023. A significantly greater coinfection detection rate was also observed in this phase vs Phase 1, while the mixed detection rate was significantly decreased in Phase 2.

Overall, these results indicated significant impacts on respiratory infections from the pandemic and associated prevention measures. Investigators concluded continued surveillance of the epidemiology of respiratory pathogens is vital.

“Future intervention strategies, including the formulation of combination vaccines, should consider the spatial and temporal interactions among pathogens to enhance the efficacy of controlling their transmission,” wrote investigators.

References

1. Pediatric Investigation study reports significant shifts in post-COVID respiratory infection trends in children. EurekAlert. February 02, 2026. Accessed February 04, 2026. https://www.eurekalert.org/news-releases/1114911
2. Ye W, Zheng J, Yang Y, et al. Interaction analysis of non-bacterial respiratory pathogens during and after the coronavirus disease 2019 pandemic in two cities along the eastern coast of China. Pediatric Investigation. 2026. doi:10.1002/ped4.70034