S100A9 and susceptibility to pneumonia measurement: This meta-analysis aims to assess the significance of S100 proteins (S100A4, S100A8, S100A9, S100A12, S100B, S100P) and interleukins (IL) (IL-6, IL-8, IL-10, IL-17, IL-1β) in COVID-19 patients, comparing those with and without pneumonia or organ failure.