Background: The transmission of diseases across nations and continents is a significant disadvantage of globalization. In December 2019, COVID-19 emerged in Wuhan, China, as a new viral illness caused by a novel beta coronavirus. The forkhead box O1 (FoxO-1) transcription factors are reported to play a significant role in maintaining normal cell physiology by regulating survival, apoptosis, and oxidative stress. 
Objective: We aimed to detect the severity of COVID-19 by clinical laboratory investigation and epigenetic biomarkers FOXO-1.
Patients and methods: This study is a prospective case-control investigation involving 50 participants divided into two groups. Group I consists of 30 patients diagnosed with COVID-19. While Group II includes 20 healthy controls. The expression levels of FOXO-1 were evaluated using real-time quantitative polymerase chain reaction (RT-qPCR).  
Results: In comparison between COVID-19 patients and healthy individuals, we use many clinical laboratory investigations such as systolic and diastolic blood pressure, RBCs, hemoglobin, hematocrit, MCHC (g/dL), PLTs, WBCs, INR, albumin, ALT, AST, LDH, PT, creatinine, sodium (Na), random blood sugar (mg/dL), and FOXO-1. There are statistically significant differences in these parameters. The analysis of the ROC curve demonstrated, along with the AUC curve, notable diagnostic performance at a cut-off value of 0.34-fold, yielding an AUC of 0.874, with a sensitivity of 88.0% and a specificity of 95.0%.
Conclusion: Then conclude from these results that the expression levels of FOXO-1 and clinical laboratory investigations, including hematological, serological, and molecular tests, serve as biomarkers in determining the severity of COVID-19.