Significance: High-frequency testing is urgently needed to help prevent the spread of COVID-19. Here, we introduce Low-cost Electrochemical Advanced Diagnostic (LEAD), a diagnostic test that detects SARS-CoV-2 within 6.5 min, costs $1.50 per unit, and uses easily assembled materials such as human angiotensin-converting enzyme 2, modified graphite leads, and a plastic vial. LEAD presents sensitivity comparable to the gold-standard methods (limit of detection for the viral spike protein = 229 fg⋅mL ^-1 ) and displays an excellent performance profile when tested using clinical saliva (100.0% sensitivity, 100.0% specificity, 100.0% accuracy) and nasopharyngeal/oropharyngeal (88.7% sensitivity, 86.0% specificity, 87.4% accuracy) samples. Finally, no cross-reactivity with other viruses was detected and the test displayed a viable shelf-life of 5 d when stored at 4 °C.