Objective  To investigate a cluster outbreak of Mycoplasma pneumoniae (M. pneumoniae) infection in a primary school in Wuchang District, analyze the distribution, epidemic characteristics, and prevention and control measures of the epidemic, and provide reference for the prevention and control of infectious disease in schools.

Methods Descriptive epidemiological method was used to analyze the cases distributions in the epidemic; all the relevant cases were searched according to the case definition; a standardized case investigation was conducted for all the cases, the cases’ medical records were collected, and throat swabs were collected from the cases for the detection of nucleic acid of M. pneumoniae.

Results The epidemic lasted for 27 days from September 5th to October 1st, 2023, and a total of 31 laboratory confirmed and clinically diagnosed cases were reported, all the cases were students from class 3, grade 2. The attack rate was 68.89%. All the cases sought medical treatment at local medical institutions and 58.06% of the cases were hospitalized. The attack rate was 67.86% in boy students and 70.59% in girl students, the difference was not significant (χ²=0.037, P>0.05); The main clinical symptoms of the cases were cough and fever, occasional dizziness, headache and expectoration. Most cases had lung imaging changes at different degrees. After combined treatment with azithromycin, no severe or critical cases occurred, indicating a good prognosis. The epidemic was effectively controlled after taking prevention and control measures, such as class suspension, case monitoring, strengthened ventilation and disinfection, and gathering activity cancel.

Conclusion This was a school epidemic caused by M. pneumoniae infection, mainly due to the failure in isolation of the infected students in time. The symptoms of this disease were atypical and the progress was slow. In this case, the combined therapy of azithromycin was effective. In the epidemic season, it is suggested to strength health education, strictly implement routine prevention and control measures, such as morning and noon health checks, in schools. Meanwhile, it is necessary to improve the home isolation management of infected students to effectively control the spread of the epidemic in schools.