Evaluation of simple lateral flow immunoassays for detection of SARS-CoV-2 neutralizing antibodies

Immunization for the generation of protective antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has emerged to be highly effective in preventing hospital admission, need for intensive care treatment and high mortality in the current SARS-CoV-2 pandemic. Lateral flow immune assays (LFIAs) offer a simple and competitive option to monitor antibody production after vaccination. Here, we compared the diagnostic performance of three different lateral flow assays in detecting nucleocapsid protein (NP), S1 subunit (S1) and receptor binding domain (pseudo)-neutralizing antibodies (nRBD) in sera of 107 health care workers prior (V1), two weeks (V2) after first vaccination with BNT162b2 as well as three weeks (V3) and eight months later (V4). In sera at V1, overall specificity was >99%. At V3, LFIAs showed sensitivities between 98.1 and 100%. The comparison of S1 and nRBD LFIA with S1 ELISA and a focus reduction neutralization assay (FRNT) revealed high concordance at V3. Thus, the use of lateral flow immunoassays appears to have reasonable application in the short-term follow-up after vaccination for SARS-CoV-2.