Fig. 1From: Spectroscopic methods for COVID-19 detection and early diagnosisSubtraction Raman spectra of (a) the average CTRL signal versus the average signal of COV + , (b) the average CTRL signal versus the average COV- spectrum and c the average COV + signal versus the average COV − signal. The ± 0.005 ΔI intervals are indicated in the graphs, confirmed by the error propagation from the spectra standard deviation. d Overlapped average spectra of CTRL, COV + and COV − with the main different regions highlighted. (With permission from [16])Back to article page