Infectious Diseases Society of America has released Guidelines on Serologic Testing for the Diagnosis of COVID-19. IDSA's goal was to develop evidence-based recommendations that assist clinicians, clinical laboratories, patients and policymakers in decisions related to the optimal use of SARS-CoV-2 serologic tests in a variety of settings. The guidelines also highlight important unmet research needs pertaining to the use of anti-SARS-CoV-2 antibody tests for diagnosis, public health surveillance, vaccine development and the selection of convalescent plasma donors.
Main recommendations include-
Recommendation 1: The IDSA panel suggests against using serologic testing to diagnose SARS-CoV-2 infection during the first two weeks (14 days) following symptom onset (conditional recommendation, very low certainty of evidence).
Recommendation 2: When SARS-CoV-2 infection requires laboratory confirmation for clinical or epidemiological purposes, the IDSA panel suggests testing for SARS-CoV-2 IgG or total antibody three to four weeks after symptom onset to detect evidence of past SARS-CoV-2 infection (conditional recommendation, very low certainty of evidence).
Remark – When serology is being considered as an adjunct to NAAT for diagnosis, testing three to four weeks post-symptom onset maximizes the sensitivity and specificity to detect past infection.
Remark – Serosurveillance studies should use assays with high specificity (i.e., >99.5%), especially when the prevalence of SARS-CoV-2 in the community is expected to be low.
Recommendation 3: The IDSA panel makes no recommendation either for or against using IgM antibodies to detect evidence of past SARS-CoV-2 infection (conditional recommendation, very low certainty of evidence).
Recommendation 4: The IDSA panel suggests against using IgA antibodies to detect evidence of past SARS-CoV-2 infection (conditional recommendation, very low certainty of evidence).
Recommendation 5: The IDSA panel suggests against using IgM or IgG antibody combination tests to detect evidence of past SARS-CoV-2 infection (conditional recommendation, very low certainty of evidence).
Remark – IgM or IgG combination tests are those where detecting either antibody class is used to define a positive result.
Recommendation 6: The IDSA panel suggests using IgG antibody to provide evidence of COVID-19 infection in symptomatic patients with a high clinical suspicion and repeatedly negative NAAT testing (weak recommendation, very low certainty of evidence).
Remark – When serology is being considered as an adjunct to NAAT for diagnosis, testing three to four weeks post-symptom onset maximizes the sensitivity and specificity to detect past infection.
Recommendation 7: In pediatric patients with multisystem inflammatory syndrome, the IDSA panel suggests using both IgG antibody and NAAT to provide evidence of current or past COVID-19 infection (strong recommendation, very low certainty of evidence).
Recommendation 8: The IDSA panel makes no recommendation for or against using capillary versus venous blood for serologic testing to detect SARS-CoV-2 antibodies (knowledge gap).
The effectiveness and durability of anti-SARS-CoV-2 antibody responses, however, have not yet been defined. Thus, serologic testing cannot be used to determine immune status.
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Infectious Diseases Society of America