Introduction and Aim: An optimal immune status is essential for recovery from pneumonia; hence, measuring indicators of the immune status is important. Therefore, we aimed to investigate whether Quantiferon monitoring (QFM) could predict healthcare-associated infection according to the immune state of pneumonia patients.

Patients and Methods: This was a prospective, single-center study of patients hospitalized for pneumonia. Study patients were enrolled between October 2020 and November 2021 and were >18 years of age. Here, QFM was done at hospital admission (D1, QFM baseline) and the seventh day after the first collection (D2, 2nd QFM). A total of 90 patients were analyzed using the D1 QFM and divided into two groups: the healthcare-associated infection group (HCAI) with 41 patients (45.6 %) and the non-HCAI group with 49 patients (54.4 %).

Results: The D1 QFM value was significantly higher in the non-HCAI group than in the HCAI group (5.75 IU/mL vs. 4.40 IU/mL, respectively). The D2 QFM level was significantly higher in the non-HCAI group than in the HCAI group (6.10 IU/mL vs. 4.38 IU/mL, respectively). When comparing D1 and D2 QFM levels within the groups, the D2 level was higher than the D1 level in the non-HCAI group (5.75 IU/mL vs. 6.10 IU/mL, respectively). In the HCAI group, however, the D2 QFM level was lower than the D1 QFM level (4.40 IU/mL vs. 4.38 IU/mL, respectively).

Conclusions: The results of this study suggest that QFM can be used as a biomarker to predict patient immune status concerning HCAI, with notable implications for the effective understanding of pneumonia recovery.