905. Epidemiology of Enterovirus D68 in the US: New Vaccine Surveillance Network, 2017–2022

Abstract Background Provisional US data indicated that enterovirus D68 (EV-D68) circulated during summer 2022. However, in contrast to 2018 (a previous high circulation year), EV-D68 circulation in 2022 was associated with unusual increases in asthma-specific healthcare visits and a lack of concomitant increases in acute flaccid myelitis (AFM). To explore these distinctions by year, we characterized respiratory EV-D68 circulation in 2022 and compared patient characteristics in 2022 to 2018. Methods We enrolled children aged < 18 years with acute respiratory illness (ARI) seeking care in an emergency department (ED) or as an inpatient (IP) across 7 US medical centers in the New Vaccine Surveillance Network (NVSN). Data sources included parent interview, medical chart review, and collection of a respiratory swab for molecular virus testing. Swabs were tested for EV-D68 from Jul–Nov 2017–2020, and year-round from Jul 2021. A convenience sample of EV-D68-positive swabs was sequenced. We assessed monthly EV-D68 percent positivity among children with ARI. We examined demographics, underlying conditions, and severity markers among children with EV-D68 in 2018 and 2022, by care setting (ED vs IP) and used 0.05 as a threshold of statistical significance. Results Between 2017–2022, there were 994 ED and IP EV-D68 detections at NVSN sites, with distinct peaks during the Jul-Nov testing periods in 2018 and 2022 (Figure). All viruses sequenced in 2018 and 2022 were lineage B3. Compared to 2018, IPs with EV-D68 in 2022 less frequently reported any underlying medical condition or a history of asthma, yet more frequently required supplemental oxygen or intubation (Table). Supplemental oxygen use was also more common among ED patients in 2022 than 2018 (13% vs 6%; p=0.028). Asthma exacerbation was a common primary discharge diagnosis among IPs but was less common in 2022 than 2018 (43% vs 53%; p=0.030). Conclusion EV-D68 circulation was high in 2018, appeared to be disrupted in 2020, and returned with early and high circulation in 2022. Compared to 2018, EV-D68 may have caused more severe respiratory disease in 2022, including in otherwise healthy children. The lack of AFM observed in 2022 despite high EV-D68 circulation needs further investigation. Disclosures Mary A. Staat, MD, MPH, CDC: Grant/Research Support|Cepheid: Grant/Research Support|Merck: Grant/Research Support|NIH: Grant/Research Support|Pfizer: Grant/Research Support|Up-To-Date: Honoraria Elizabeth P. Schlaud