TTR and infection: The ROC curve results indicated that prealbumin was more efficient than CRP in identifying co‐infection from Omicron (AUC: 0.867 vs. 0.724) or Flu A/B (AUC: 0.797 vs. 0.730), and joint prediction significantly improved the diagnostic ability to discriminate co‐infection from mono‐infection (AUC: 0.934 and 0.887).