This computational study reanalyzed publicly available transcriptomic datasets from COVID-19 and influenza patient samples to identify candidate blood-based gene biomarker signatures using pathway analysis and machine learning. The analysis identified a three-gene signature (IGKC, IGLV3-16, SRP9) specific to COVID-19 validated at 93.09% accuracy and a four-gene signature (FMNL2, IGHV3-23, IGLV2-11, RPL31) for differential diagnosis from influenza validated at 87.2% accuracy on external datasets.