Etiological analysis of acute respiratory infections in hospitalized children after the relaxation of COVID-19 non-pharmacological interventions in Quzhou, China.

BACKGROUND

Acute respiratory infections (ARIs) can cause morbidity and mortality in children. This study was to determine the characteristics of pathogens in hospitalized children with ARIs after the relaxation of COVID-19 non-pharmacological interventions (NPIs) in Quzhou, China.

METHODS

Hospitalized children with ARIs were enrolled between May and October 2023, and thirteen common respiratory pathogens were tested by fluorescent quantitative polymerase chain reaction. Mono- and co-infections were assessed, and the association between pathogens and age was explored using restricted cubic spline analysis.

RESULTS

A total of 1225 children were included, 820 of them detected one pathogen and 238 of them detected two or more pathogens. The dominant pathogen varies monthly. Mycoplasma pneumoniae (Mp) was the most common pathogen in monoinfection, followed by respiratory syncytial virus (RSV) and human rhinovirus (HRV), while influenza virus was detected at a lower rate. Mp + HRV was the most common combination of coinfections. The detection rates of Mp and HRV were higher in coinfections than in monoinfection, but there was no difference in the detection rate of RSV. Children aged 1-3 years had the highest positive detection rates and were more likely to be infected with multiple pathogens, with 40% of respiratory pathogen monoinfection and 47.48% of coinfections (χ = 4.245, P = 0.039). In the restricted cubic spline models, a J-shaped association was consistently observed between age and Mp infection, the risk of HRV first increased and then decreased, the risk of RSV was relatively flat until 1.5 years and then decreased rapidly.

CONCLUSION

Our study revealed the epidemiological characteristics of ARIs pathogens after the relaxation of NPIs. The positivity rates of Mp, RSV, and HRV are the highest, while those of influenza virus are still low. Additionally, age and season affect the distribution of respiratory pathogens. These findings underscore the importance of ongoing regional pathogen surveillance to guide local public health responses.