Introduction
With the development of detection technology, In a population-based study[1], had found that the detection of virus has exceeded that of bacteria in patients with pneumonia, the disease burden of viral pneumonia exceeds that of other types of pneumonia, and viral pneumonia indicates a worse prognosis.A review[2]on the CAP in China,The incidence rate, among the patients (as of 2017), ranged from 29.8 to 221.0 people per 10,000 individuals. M. pneumoniae is the most common pathogen in adults, with 15.01% of patients being diagnosed, followed by streptococcal pneumonia in 11.68%, influenza A virus in 12.28%, and fungi in 8.28%. And the prevalence of other viral pneumonia under the influence of COVID-19 is unclear.so far,Daniel K. Yeoh[3],It was found that by the winter of 2020, the detection rates of respiratory Scyvirus and influenza in Western Australian children had been reduced by 98.0% and 99.4% respectively compared with before COVID-19, respectively. On January 6, 2020, China National Center for Disease Control and Prevention launched a secondary emergency response.The National Center for Disease Control and Prevention launched a first-level emergency response on On January 20, 2020. The National Health Commission announced that COVID-19 would be included in a class B infectious disease and would be under class A management. On January 6, 2020,SiChuan Province launched the public health emergency level emergency response. On March 24,2020, the third-level response would gradually open up the resumption of production and school. Since then, China has been adopting regular epidemic management.While the situation of viral infection in the pneumonia in adults is unclear, therefore, we designed this study to compare the etiological evolution of viral pneumonia before and after COVID-19.