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

Objective: The aim of this study was to monitor the spectrum of viral pathogens involved in febrile rash illness (FRI) and their epidemiology. Methods: 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). Results: 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. Conclusions: 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.