P-1210. Resurgence of Parechovirus-A3 Infection in Neonates and Young Infants after the Coronavirus Disease 2019 Pandemic in Japan

Abstract Background Parechovirus-A (PeV-A), especially PeV-A3, is a common cause of viral sepsis and encephalitis in neonates and young infants (age < 4 months). The strict infection control measures and non-pharmaceutical interventions of the coronavirus disease 2019 (COVID-19) pandemic affected the epidemiological profiles of community-acquired diseases. However, the effects of the pandemic on the epidemiology of PeV-A infection in this age group are unknown. Methods This prospective multicenter observational study was conducted between 2019 and 2023 in 12 Japanese prefectures. Neonates and young infants hospitalized for suspected sepsis and/or meningoencephalitis were included. Samples were sent to the laboratory of Niigata University, and PeV-A was detected by real-time PCR. The 7 hospitals introduced the BioFire Filmarray meningitis/encephalitis (FA/ME) panel in 2020. Genotype was determined by direct sequencing and BLAST analysis, and the phylogenetic tree of viral protein 1 region of PeV-A3 was constructed. Results 131 patients with PeV-A infection were identified (n = 36 in 2019, n = 7 in 2020, n = 1 in 2021, n = 27 in 2022, and n = 60 in 2023). Genotype was PeV-A3 in 124 cases and PeV-A4 in 2 cases in 2022 and unknown in 5 cases in 2019. Seasonal peaks and other characteristics were similar before and after the COVID-19 pandemic (i.e., in 2019 vs. 2023). Body temperature, fever duration, and the proportion of patients with rash declined; however, the proportion of those with abdominal distention increased. The FA/ME panel was more frequently used after the start of the pandemic (3.2% vs. 53.3%, P < 0.001). The proportion of those with sepsis declined from 83.9% to 63.3% (P = 0.04), but the proportions of those with encephalitis and those requiring ICU admission were similar. No patient had sequelae at discharge. PeV-A3 has evolved within a single clade with two branches. Conclusion The number of PeV-A3 infections was higher after the start of the COVID-19 pandemic, possibly because low PeV-A3 activity early in the pandemic increased the number of susceptible pregnant women, thus leading to a decline in maternally derived antibodies. In addition, use of the FA/ME panel might help detect mild cases. Disclosures All Authors: No reported disclosures