Figure 5. Validation of the FC Jurkat‐S method.

• A
  A total of 52 serum samples from Hospital Universitario La Princesa (HUP) and 52 samples of pre‐COVID donors stored at the CBMSO were tested by the flow cytometry method and classified according to the S/EGFR‐based Score. Of the 52 HUP samples, a total of 40 were from donors testing positive by PCR and by an ELISA test, six were from donors testing negative by PCR but positive by ELISA, one from an individual testing negative by ELISA and positive by PCR, and five were not tested by PCR. Box and whiskers are shown to represent the minimum and maximum values as well as the median. All datapoints are shown. The broken line indicates the threshold for a Score value of 0.024.
• B, C
  Four HUP serum samples giving discrepant results by PCR and by the flow cytometry method were tested in the neutralization assay of pseudotyped lentivirus (Fig 4A). Data represent the mean ± SD of duplicates. *P < 0.05; **P < 0.005; ****P < 0.00005 (paired two‐tailed t‐test comparing all serum dilutions to the pre‐COVID sample).