Colloidal gold immunochromatographic assay (GICA) is an effective screening method for identifying detectable anti-SARS -CoV-2 neutralizing antibodies

Introduction: A large number of COVID-19 patients are in recovery, and millions of people are vaccinated for COVID-19 globally. This calls for a rapid screening strategy of SARS-CoV-2 protective antibodies, generated in rehabilitated and vaccinated populations. Methods: Serum samples collected over a follow-up period of six months from 306 COVID-19 cases discharged from Wuhan Tongji Hospital were analyzed. Anti-S Abs were detected by colloidal gold immunochromatographic assay (GICA), and neutralizing antibodies (nAbs) were detected by chemiluminescent microparticle immunoassay (CMIA). Results: Most COVID-19 survivors tested positive for anti-S Abs (83.7%) and nAbs (98.0%) 6 months after being discharged from the hospital, and the levels of anti-S Abs in the blood were highly positively correlated with nAbs (r = 0.652, P < 0.0001). The positivity rate of nAbs for patients with anti-S Abs positive was 100%. Conclusions: There is a good agreement between anti-S Abs detected by GICA and nAbs detected by CMIA. It indicates that anti-S Abs detected by GICA may be used as a cheaper screening strategy for detectable SARS-CoV-2 nAbs in COVID-19 convalescent individuals. (c) 2021 The Author(s). Published by Elsevier Ltd on behalf of International Society for Infectious Diseases. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).