A novel application of delayed-type hipersensitivity reaction to measure cellular immune response in SARS-CoV-2 exposed individuals.

Abstract Objective To understand the anti-virus adaptive immune response occurring during SARS-Cov-2 infection is necessary to have methods to investigate cellular and humoral components. The goal of this study has been to investigate the utility of a specific spike-DTH test using a coronavirus recombinant protein in COVID-19 patients. Methods DTH studies were performed by intradermal injection of a commercial recombinant spike protein from SARS-CoV-2 along with conventional serology studies. Results Fifty-one COVID-19 patients were studied showing 84,3% of concordance with spike-DTH and anti-RBD-IgG. Spike-DTH was superior to identify seven more COVID-19 individuals. A high specificity was found with no positive spike DTH reactions in the non-sick individuals. The skin test also showed more stable results over time while specific anti-RBD-IgG decreased gradually. Clinical severity groups also showed a progressive gradient of larger positive spike-DTH. Conclusion Specific spike DTH test seems to be an easy method to study cell immune response.