Impact of recent influenza A virus infection on clinical characteristics and outcomes in severe coronavirus disease 2019 adult inpatients

Background: Coronavirus disease 2019 (COVID-19) is a current global pandemic. However, impact of recent influenza A virus infection on the clinical course and outcomes of severe COVID-19 adult inpatients needs to be further explored. Methods: : In this retrospective cohort study, severe, laboratory confirmed COVID-19 adult patients from Wuhan Tongji Hospital were included. Data were obtained from electronic medical records and compared between patients with and without recent influenza A virus infection. Results: : 200 patients were included, 51.5% with recent influenza A virus infection. Recent influenza A virus infection group presented with longer persistence of cough and sputum from illness onset (35.0 vs. 27.0 days, P = 0.018) and (33.0 vs. 26.0 days, P = 0.015), respectively. Median time of progression to critical illness from illness onset was shorter (day 11.5 vs. day 16.0, P = 0.034). Time to clinical improvement and length of hospital stay were longer in recent infection group (23.0 vs. 19.0 days, P = 0.044) and (22.0 vs. 18.0 days, P = 0.030), respectively. Conclusions: : Patients with recent influenza A virus infection showed a delay in time to clinical improvement and increased length of hospital stay. There is a high clinical need to improve the detection of common respiratory pathogens to identify co-infection during the epidemic of COVID-19.