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Abstract

Objective Following the full relaxation of COVID-19 control measures in China at the end of 2022, there was a resurgence of pediatric Mycoplasma pneumoniae pneumonia (MMP) outbreaks. Methods We performed a retrospective study of children with M. pneumoniae pneumonia who were admitted to the Women and Children's Hospital of Ningbo University between January 2022 and December 2023. Demographic and clinical characteristics and proportion of A2063G/A2064G mutant train were compared between 2022 and 2023. Results Among the 13013 children hospitalized with pneumonia in 2022 and 2023, M. pneumoniae infections were identified in 4889 cases (37.57%). Notably, the positive rate of M. pneumoniae was significantly higher in 2023 (44.86%, 4339/9672) compared to 2022 (16.46%, 550/3341), with a rapid increase observed since May 2023. The proportion of M. pneumoniae pneumonia patients aged three and above was significantly higher in 2023 than in 2022 (P<0.001). Regarding severity, 5.45% (30/550), and 3.43% (149/4339) of cases were diagnosed as severe pneumonia in 2022 and 2023, respectively (P<0.05). However, they had a lower duration of fever and length of stay (LOS) in 2023 than those in 2022 (P<0.05). Meanwhile, more children with severe MMP took therapeutic measures, such as oxygen uptake and bronchial lavage in 2023 than those in 2022 (P<0.05). The mutation rate for A2063G/A2064G exceeded 70% throughout the period, with some months even recording a perfect 100% mutation rate. Conclusions Due to the relaxation of strict public health measures, China entered the M.pneumoniae pandemic cycle earlier than European countries in 2023. The A2063G/A2064G mutant strain of M. pneumoniae has become the primary pathogenin children in Ningbo recently. Prompt therapeutic measures, such as oxygen uptake and bronchial lavage, may represent an effective strategy for reducing the duration of fever and the length of hospital stay in pediatric patients with severe M. pneumoniae pneumonia.

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