Abstract:

BackgroundSoon after the emergence of community transmission of COVID19, the Chinese government has introduced a series of nonpharmaceutical interventions (NPI) to eliminate COVID19 and these NPIS have already affected the prevalence of other common respiratory pathogens. 
 ObjectiveThis study aimed to analyze the epidemiological characteristics of mycoplasma pneumoniae (Mp) and chlamydia trachomatis (CT) of acute respiratory infections （ARTI） in children during the COVID19 pandemic. 
 DesignObservational study.
 MethodsRespiratory specimens for the detection of Mp, CT and other 9 common respiratory viruses were collected from children with ARTI at Children's Hospital of Fudan University from February 2019 to May 2021. The detection data were divided into the group of single pathogen infection (only Mp and CT were detected) and coinfection (Mp+CT, Mp or CT +any one or more of 9 common respiratory viruses and Mp+CT+ one or more of 9 common respiratory viruses). Respiratory specimens (nasopharyngeal aspirates/bronchoalveolar lavage fluid) were collected and tested in our hospital. a. Three satages were compared including "preCOVID19" period: from February 1, 2019 to January 31, 2020, without actively implemented nationwide NPI; b."COVID19"period, from February 1, 2020 to May 31, 2020, when strict nationwide NPI were implemented and schools were closed; c."postCOVID19"period, from June 1, 2020 to May 31, 2021, when nationwide NPI were relaxed, schools were reopened and social work was resumed. All the enrolled samples were divided into 5 age groups: ≤28 days, ~12 months, ~3 years, ~6 years and ≥7 years according to the age at the time of ARTI diagnosis.
 Main outcome measuresThe epidemiological changes of Mp and CT during the COVID19 pandemic.
 ResultsA total of 10 358 specimens tested for respiratory pathogens were enrolled in this analysis, including 6 080 in the preCOVID19 period, 754 in the COVID19 period and 3 524 in the postCOVID19 period. The total number decreased by 42.04% ［(6 080-3524)/6 080］during postCOVID19 when compared to preCOVID19. Among all the enrolled patients, 6 138 were male and 4 220 were female. The overall detection rate of Mp was 12.39%, the observed prevalence declined sharply and was decreased by 96.29% ( P<0.001) with a significant difference. The overall detection rate of CT was 1.45%. The detection rate showed an increasing trend and was increased by 65.49% (P=0.003). The detection rate of single Mp and CT infection was 10.84%. Compare to the pre-COVID-19 period, the detection rate of Mp was decreased by 96.05% and the detection rate of CT was increased by 119.70% in the post-COVID-19 period, with a significant difference. The overall coinfection rate was 2.89%. The coinfection rate of Mp was decreased by 97.32% (P<0.001), while no significant difference was observed in the coinfection rate of MP+CT and CT. Mp peaked in summer during the pre-COVID-19 period, whereas the annual peak was interrupted after the NPI were adopted. CT was detected throughout the whole study period. The examination rates were sharply decreased with the increase of age in the group of older than 12 months in both three periods, while the detection rate of Mp showed a great increase in the pre-COVID-19 period, an increase in the COVID-19 period and a slight increase in the post-COVID-19 period. The increase in the detection rate of CT was observed in the age of ≤28 days and -12 months in all three periods, while the examination rate and detection rate of CT showed a sharply decrease in children older than 12 months with the increase of age in the whole study period.
 ConclusionThe public health interventions aiming to eliminate COVID-19 have great impact on the prevalence of the atypical pathogens. The detection rate of Mp was significantly reduced, and the seasonality of Mp was disappeared, while the detection rate of CT was significantly increased.





Key wordsAcute respiratory tract infections;Mycoplasma pneumoniae;Chlamydia trachomatis;Epidemiology

Key words: Acute respiratory tract infections, Mycoplasma pneumoniae, Chlamydia trachomatis, Epidemiology