Emergence of Echovirus 11 in Severe and Neonatal Enterovirus Infections: A 9-Year Retrospective Study in Taiwan Before and After the COVID-19 Pandemic.
Enteroviruses (EVs) cause a wide range of pediatric illnesses. In Taiwan, changes in serotype distribution and COVID-19-related public health measures may have influenced recent EV trends. We retrospectively reviewed EV-positive pediatric inpatients (< 18 years) at National Taiwan University Hospital from 2015 to 2023. Cases were identified via PCR or viral culture. Among 678 cases, incidence declined markedly during the COVID-19 period but rebounded after public health restrictions were relaxed, with seasonal peaks in June persisting. Echovirus 11 emerged as the predominant serotype among neonatal cases (23.1%) and severe cases (9.5%), whereas EV-A71 was mainly associated with hand-foot-mouth disease. Severe cases were significantly younger (median 0.8 vs. 1.5 years, p = 0.002) and more likely to have underlying conditions, including congenital syndromes and cardiovascular diseases. The only mortality occurred in a neonate with echovirus 11 infection. Viral or bacterial co-detections were not associated with severity. Echovirus 11 has replaced EV-A71 as a leading cause of severe and neonatal EV infections in Taiwan. Younger age and underlying conditions were significant risk factors for severe disease. Ongoing surveillance and vaccine development should prioritize currently circulating virulent serotypes and high-risk pediatric populations.