Viral Pathogenic Spectrum and Epidemiological Characteristics of Febrile Rash Illness in China From 2009 to 2021

The aim of this study was to monitor the spectrum of viral pathogens involved in febrile rash illness (FRI) and their epidemiology. A large-scale study was conducted in multiple provinces of China from 2009 to 2021. A total of 14,168 patients of all age groups were enrolled and tested for seven common viruses causing FRI: measles virus (MV), rubella virus (RuV), enterovirus (EV), varicella zoster virus (VZV), human parvovirus B19 (HPV B19), human herpes virus 6 (HHV6), and dengue virus (DENV). Of 14,168 patients with FRI, 9,443 tested positive for a virus, thus yielding a viral positivity rate of 66.65%. Among the seven viruses detected, EV (61.04%), MV (23.32%), RuV (7.74%), and VZV (5.26%) had high detection rates and exhibited different age-specific positivity rates and seasonal prevalence patterns. Early in the Coronavirus Disease 2019 (COVID-19) pandemic, the number of EV, MV, RuV, and VZV cases significantly declined, and the seasonal patterns also changed in 2020, with delay or disappearance of traditional epidemic peaks. EV, MV, RuV, and VZV were found to be the main causal pathogens of FRI among patients in China, and their epidemic levels and seasonal patterns changed during the COVID-19 pandemic, because of large-scale implementation of non-pharmacological interventions.