Analysis of infection indicators and risk factors for influenza A after the COVID-19 pandemic.

The flu outbreak after the coronavirus disease 2019 (COVID-19) pandemic has put a heavy burden on the medical system. We aimed to investigate the infection indicators and risk factors for influenza A virus, with the intention of offering valuable insights for clinical diagnosis and treatment. A total of 1590 throat swabs were collected from patients with influenza-like illness admitted to our hospital for treatment in March 2023. Influenza virus in infected patients was detected by the rapid antigen method and qPCR. We used statistical methods to compare clinical manifestations and laboratory tests between positive and negative patients. Among the 1590 influenza-like illness patients, 1004 (63.1%) were infected with influenza A, mainly children aged 0-9 years (52.8%); more males than females were infected, and the main clinical symptoms were fever, cough, diarrhea, nausea and vomiting, and muscle soreness. The leukocyte (WBC), lymphocyte (LYM), eosinophil (EOS), platelet (PLT), C-reactive protein (CRP) and lymphocyte/monocyte (LMR) levels in the positive group were lower than those in the negative group, while the neutrophil (NEU) and monocyte (MON) levels were higher than those in the negative group (P<0.05). Multivariate logistic regression analysis showed that age 0-9 years, cough, antiviral treatment time>48 h, and reduced PLT and LMR levels were independent risk factors for influenza A patients.