SARS-CoV-2 Pandemic Non-Pharmacologic Interventions Temporally Associated with Reduced Pediatric Infections Due to Mycoplasma pneumoniae and Co-Infecting Respiratory Viruses in Arkansas (preprint)

Introduction: Non-pharmacologic interventions (NPIs), such as universal masking, implemented during the SARS-CoV-2 pandemic have reduced respiratory infections among children. This study focuses on evaluating the impact of NPIs on Mycoplasma pneumoniae infections in children, analyzing data from two hospitals in Arkansas, and examining age-related differences and coinfections with other viruses. Methods: The study was approved by the Institutional Review Board and included patients aged [≤]18 years with upper respiratory tract symptoms. Data from the FilmArray(R) Respiratory Panel (FARP) were collected and divided into pre-NPI and NPI periods for analysis. Total test positivity rate and interval change in the positivity rate were evaluated. Statistical differences were determined by Chi-square ({chi}-independence) analysis. Results: A total of 68,949 tests were performed with a statistical increase in testing during the NPI period. The overall test positivity rate for M. pneumoniae decreased by 74% (0.86% to 0.03%) during the NPI period, and the preschool age group had the highest number of positive tests in the pre- and NPI periods (Pre-NPI: n=40, NPI: n=12 positive tests, p=<0.001). The reduction in M. pneumoniae infections was consistent across age groups. Coinfections with other respiratory viruses, particularly human rhinovirus/enterovirus, were observed at much lower levels. Conclusions: NPIs effectively reduced M. pneumoniae in pediatric patients in Arkansas, and coinfections with specific viruses still occurred, albeit at lower levels during the SARS-CoV-2 pandemic. As NPIs are relaxed and the pandemic ends, we expect M. pneumoniae infections to return to pre-pandemic levels within the next 1-2 years.

Upper airway gene expression reveals a more robust innate and adaptive immune response to SARS-CoV-2 in children compared with older adults (preprint)

Unlike other respiratory viruses, SARS-CoV-2 disproportionately causes severe disease in older adults and only rarely in children. To investigate whether differences in the upper airway immune response could contribute to this disparity, we compared nasopharyngeal gene expression in 83 children (<19-years-old; 38 with SARS-CoV-2, 11 with other respiratory viruses, 34 with no virus) and 154 adults (>40-years-old; 45 with SARS-CoV-2, 28 with other respiratory viruses, 81 with no virus). Expression of interferon-stimulated genes (ISGs) was robustly activated in both children and adults with SARS-CoV-2 compared to the respective non-viral groups, with only relatively subtle distinctions. Children, however, demonstrated markedly greater upregulation of pathways related to B cell and T cell activation and proinflammatory cytokine signaling, including TNF, IFN{gamma}, IL-2 and IL-4 production. Cell type deconvolution confirmed greater recruitment of B cells, and to a lesser degree macrophages, to the upper airway of children. Only children exhibited a decrease in proportions of ciliated cells, the primary target for SARS-CoV-2, upon infection with the virus. These findings demonstrate that children elicit a more robust innate and adaptive immune response to SARS-CoV-2 infection in the upper airway that likely contributes to their protection from severe disease in the lower airway.