Positive COVID19-PCR patients as negative controls for COVID19 antibody tests.

COVID-19 serological antibody tests are recently needed for a relatively quick, affordable, and valuable assessment of the immunity toward COVID-19 infection. Furthermore, they can help with evaluating the sufficiency of the vaccination process and its longevity. There are limitations in the current approach of choosing the positive and negative control samples for the validation of those tests. Herein, we are proposing the use of blood samples from positive COVID-19 patients, at the beginning of the disease course, as negative control blood samples for the antibody tests. For more precision, both the negative and the positive control samples can be obtained from the same patients where the accuracy of the test will depend on its ability to detect the seroconversion, from negative to positive antibodies detection, within the same patient. Furthermore, when the validation of the test is accompanied by detecting/sequencing the viral genome in those COVID-19 patients, this can also aid in determining the accuracy of the test in detecting the immune response to specific viral variants. The latter notion is needed for the proper management of the COVID-19 crisis, new vaccines' manufacturing, and evaluating the vaccines' efficiencies. Finally, this approach could be requested/formulated by the regulatory agencies as part of the tests' validation and can be "in-house" obtained by health facilities before its clinical use.