Notes from the Field: Reemergence of Mycoplasma pneumoniae Infections in Children and Adolescents After the COVID-19 Pandemic, United States, 2018–2024

Abstract

Mycoplasma pneumoniae is a common cause of respiratory infections, particularly in school-aged children. Most infections display as a mild respiratory illness sometimes referred to as “walking pneumonia.” However, some persons experience severe pneumonia and require hospitalization. Significant cyclical increases in M. pneumoniae infections have been observed every 3–5 years, likely because of changes in the predominant circulating strain (1). M. pneumoniae infections are typically treated using macrolide antibiotics. Macrolide resistance varies globally, with the highest resistance prevalence (>90%) in Asia (2). After implementation of nonpharmaceutical interventions in response to COVID-19, the frequency of identified M. pneumoniae infections substantially declined beginning in 2020 (3). This pattern was also observed for other respiratory pathogens. Beginning in the fall of 2023, China and other countries identified a reemergence of this bacterium (2,4). Using data from CDC’s National Syndromic Surveillance Program (NSSP),* the percentage of M. pneumoniae–related diagnoses among all pneumonia emergency department visits were compared before, during, and after the COVID-19 pandemic. Data from the New Vaccine Surveillance Network (NVSN)† were analyzed to compare the percentage of positive M. pneumoniae laboratory test results in the United States during the same periods. During September 2023–January 2024, 14 M. pneumoniae–positive specimens collected at four NVSN sites were sent to CDC for molecular testing to identify common genetic changes that confer macrolide resistance. This activity was reviewed by CDC, deemed not research, and was conducted consistent with applicable federal law and CDC policy.§