Abstract Introduction Acute respiratory tract infections remain a major global health concern, and advances in molecular diagnostics have improved viral detection. The clinical interpretation of C-reactive protein (CRP) levels in viral respiratory infections, however, remains insufficiently defined. This study aimed to analyze CRP profiles in patients with respiratory viral infections to clarify their epidemiologic and clinical significance. Methods A retrospective analysis was conducted in 7639 respiratory specimens tested by multiplex reverse transcription–polymerase chain reaction between July 2020 and March 2025, with concurrent CRP measurement. C-reactive protein values below 0.5 mg/dL were imputed as 0.25 mg/dL for analysis. Results Among the 7639 specimens analyzed, 965 (12.63%) tested positive for respiratory viruses, with a peak observed during the winter-spring season. Viral positivity was slightly higher in women than in men. Children younger than 5 years of age exhibited the highest positivity (54.33%) but lower CRP values, whereas CRP levels increased substantially with age, reaching 12.10 mg/dL in individuals 70 years of age and older. Co-infections (13.2%) were strongly associated with lower CRP levels. Discussion Distinct CRP distributions were observed according to age and infection complexity. These findings support the use of CRP as a supplemental marker for interpreting viral respiratory tract infections and identifying atypical inflammatory responses, particularly in co-infections.
Lee et al. (Tue,) studied this question.