Co‐infection of influenza A virus and SARS‐CoV‐2: A retrospective cohort study

Cheng, Yuan; Ma, Jing; Wang, He; Wang, Xi; Hu, Zhanwei; Li, Haichao; Zhang, Hong; Liu, Xinmin

The coronavirus 2019 (COVID‐19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2), has spread across the world and is responsible for over 1,686,267 deaths worldwide. Co‐infection with influenza A virus (IFV‐A) during the upcoming flu season may complicate diagnosis and treatment of COVID‐19. Little is known about epidemiology and outcomes of co‐infection. Data for 213 COVID‐19 patients treated at Tongji Hospital in Wuhan from January 28, 2020 to March 24, 2020 were retrospectively analyzed. Ninety‐seven of the patients (45.5%) tested positive for anti‐ IFV‐A immunoglobulin M antibodies. The clinical characteristics were described and analyzed for patients with SARS‐CoV‐2 infection only and patients with SARS‐CoV‐2/IFV‐A co‐infection. Patients with co‐infection showed similar patterns of symptoms and clinical outcomes to patients with SARS‐CoV‐2 infection only. However, an increased expression of serum cytokines (interleukin‐2R [IL‐2R], IL‐6, IL‐8, and tumor necrosis factor‐α) and cardiac troponin I, and higher incidence of lymphadenopathy were observed in patients with SARS‐CoV‐2 infection only. Male patients and patients aged less than 60 years in the SARS‐CoV‐2 infection group also had significantly higher computed tomography scores than patients in co‐infection group, indicating that co‐infection with IFV‐A had no effect on the disease outcome but alleviated inflammation in certain populations of COVID‐19 patients. The study will provide a reference for diagnosing and treating IFV‐A and SARS‐CoV‐2 co‐infection cases in the upcoming flu season.