Infectious Diseases Society of America Guidelines on the Diagnosis of Coronavirus Disease 2019: Serologic Testing

Background The role of serologic testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has evolved during the pandemic as seroprevalence in global populations has increased. The Infectious Diseases Society of America convened an expert panel to perform a systematic review of the coronavirus disease 2019 (COVID-19) serology literature and construct updated best practice guidance related to SARS-CoV-2 serologic testing. This guideline is an update to the fourth in a series of rapid, frequently updated COVID-19 guidelines developed by the Infectious Diseases Society of America.Objective To develop evidence-based recommendations and identify unmet research needs pertaining to the use of anti-SARS-CoV-2 antibody tests for diagnosis, decisions related to vaccination and administration of monoclonal antibodies or convalescent plasma in immunocompromised patients, and identification of a serologic correlate of immunity.Methods A multidisciplinary panel of infectious diseases clinicians, clinical microbiologists, and experts in systematic literature reviewed, identified, and prioritized clinical questions related to the use of SARS-CoV-2 serologic tests. Grading of Recommendations Assessment, Development and Evaluation methodology was used to assess the certainty of evidence and make testing recommendations.Results The panel recommends against serologic testing to diagnose SARS-CoV-2 infection in the first 2 weeks after symptom onset (strong recommendations, low certainty of evidence). Serologic testing should not be used to provide evidence of COVID-19 in symptomatic patients with a high clinical suspicion and repeatedly negative nucleic acid amplification test results (strong recommendation, very low certainty of evidence). Serologic testing may assist with the diagnosis of multisystem inflammatory syndrome in children (strong recommendation, very low certainty of evidence). To seek evidence for prior SARS-CoV-2 infection, the panel suggests testing for immunoglobulin G (IgG), IgG/IgM, or total antibodies to nucleocapsid protein 3 to 5 weeks after symptom onset (conditional recommendation, low certainty of evidence). In individuals with previous SARS-CoV-2 infection or vaccination, the panel suggests against routine serologic testing given no demonstrated benefit to improving patient outcomes (conditional recommendation, very low certainty of evidence). The panel acknowledges further that a negative spike antibody test may be a useful metric to identify immunocompromised patients who are candidates for immune therapy.Conclusions The high seroprevalence of antibodies against SARS-CoV-2 worldwide limits the utility of detecting anti-SARS CoV-2 antibody. The certainty of available evidence supporting the use of serology for diagnosis was graded as very low to low. Future studies should use serologic assays calibrated to a common reference standard.