Comparative study on the incidence of non-COVID-19 viral pneumonia before and after the COVID-19 pandemic:A retrospective analysis based on respiratory non-COVID viral nucleic acid results

Background:The impact of the coronavirus disease 2019(COVID-19)pandemic on the etiology of non-COVID-19 viral pneumonia remains to be identified.We investigated the evolution of non-COVID-19 viral pneumonia in hospitalized patients before and after the COVID-19 pandemic.Methods:This is a single-center retrospective study.Patients who came to West China Hospital of Sichuan Univer-sity diagnosed with non-COVID-19 viral pneumonia from January 1,2016 to December 31,2021,were included and divided into pre-and post-COVID-19 groups according to the date of the COVID-19 outbreak in China.The results of 13 viral nucleic acid tests were compared between the two groups.Results:A total of 5937 patients(3954 in the pre-COVID-19 group and 1983 in the post-COVID-19 group)were analyzed.Compared with the pre-COVID-19 group,the proportion of patients tested for respiratory non-COVID-19 viral nucleic acid was significantly increased in the post-COVID-19 group(14.78%vs.22.79%,P<0.05).However,the non-COVID-19 virus-positive rates decreased from 37.9% to 14.6% after the COVID-19 outbreak(P<0.001).Notably,non-COVID-19 viral pneumonia caused by the influenza A virus H1N1(InfAH1N1)(2009)dropped to 0%after the pandemic.The top three viruses were InfAH1N1(2009)(13.9%),human rhinovirus(7.4%),and human adenovirus(3.4%)in the pre-COVID-19 group,and human rhinovirus(3.8%),human respiratory syncytial virus(2.0%),human parainfluenza virus(1.1%)and InfAH3N2(1.1%)in the post-COVID-19 group.Conclusions:The proportion of non-COVID-19 viral pneumonia decreased significantly after the COVID-19 out-break,among which InfAH1N1(2009)pneumonia decreased the most dramatically.