Post-pandemic resurgence and collapse of Mycoplasma pneumoniae in hospitalized children: a four-year multiplex surveillance study in China.

BACKGROUND

Understanding the post-pandemic behavior of Mycoplasma pneumoniae (MP) in children is important for respiratory pathogen surveillance and public health preparedness. This study characterized the full epidemic cycle of MP after the relaxation of COVID-19 restrictions and examined its ecological context and associated pneumonia risk.

METHODS

Four years of multiplex PCR testing data (2022-2025) from a provincial maternal and child health hospital in China were analyzed. Temporal trends in MP activity were assessed using generalized additive models. Monthly activity of co-circulating respiratory pathogens-including respiratory syncytial virus (RSV), influenza A virus (FluA), and human rhinovirus (HRV)-was compared using standardized positivity and ecological correlations. Pneumonia risk among MP-infected children was evaluated with multivariable logistic regression.

RESULTS

Mycoplasma pneumoniae showed a pronounced boom-and-bust cycle, with low activity in 2022, a sharp resurgence in 2023, and near-disappearance by 2025. As MP circulation declined, RSV, FluA, and HRV showed increased activity, indicating dynamic shifts within the respiratory pathogen ecosystem. Pneumonia risk was highest during the 2023 resurgence, remained elevated in 2024, and was no longer significantly elevated by 2025.

CONCLUSION

This study documents a complete post-pandemic MP epidemic cycle in hospitalized children in Hubei Province. The observed pattern is compatible with hypotheses of immunity debt and subsequent susceptible depletion, although direct measurement of these mechanisms was beyond the scope of this study. These findings highlight the need for continuous multi-pathogen surveillance and clinical preparedness during MP resurgence waves, as elevated pneumonia risk may extend beyond peak transmission periods.