Figure 1

Data acquisition. A routine nasopharyngeal swab sample was dissolved into the viral transport medium, analyzed with PCR, and the remnant from that sample was stored in the freezer. The frozen swab sample was thawed and inactivated by adding a viral lysis buffer liquid before the ATR-FTIR measurements. The measurement was conducted by pipetting a one drop from sample solution containing the nasopharyngeal swab sample, the viral lysis buffer and the viral transport medium onto the ATR crystal. Pipetting and measurement was repeated three times to obtain three spectra from each sample. Those three measured spectra were finally averaged so that there was one representative spectrum from each nasopharyngeal swab sample. Before ATR-FTIR measurement, the sample was vortexed to have as homogeneous material distribution as possible, and spun with centrifuge to set the whole sample to the bottom of the tube.