CD8A and susceptibility to pneumonia measurement: Increased CD4+ T%Lym, CD8+ T%Lym, DNT%Lym, warm season, a history of COPD, longer TO-A, and increased levels of CRP, LDL-C, Na+, and FCa2+ potentially cause CAP to be refractory, while the T lymphocyte count, namely, the overall cellular immunity, were impaired in r-CAP patients, and increased TC levels could be beneficial to pneumonia recovery.