Diagnostic performance of commercially available COVID-19 serology tests in Brazil

Cota, Gláucia; Freire, Mariana Lourenço; de Souza, Carolina Senra; Pedras, Mariana Junqueira; Saliba, Juliana Wilke; Faria, Verônica; Alves, Líndicy Leidicy; Rabello, Ana; Avelar, Daniel Moreira

Timely and accurate laboratory testing is essential to manage the global COVID-19 pandemic. Reverse transcription-polymerase chain reaction remains the gold-standard for SARS-CoV-2 diagnosis, but several practical issues limit the test use. Immunoassays have been indicated as an alternative for individual and mass testing. Objectives: To access the performance of twelve serological tests for COVID-19 diagnosis. Methods: We conducted a blind evaluation of six lateral flow immune assays (LFIAs) and six enzyme-linked immunosorbent assays (ELISA) commercially available in Brazil to detect anti-SARS-CoV-2 antibodies. Results: Considering patients with seven or more days of symptoms, the sensitivity ranged from 59.5% to 83.1% for LFIAs and from 50.7% to 92.6% for ELISAs. For both methods, the sensitivity increased with clinical severity and days of symptoms. The agreement between LFIA performed in digital blood and serum was moderate. Specificity was, in general, higher for LFIAs than for ELISAs. Infectious diseases prevalent in the tropics, such as HIV, leishmaniasis, arboviruses and malaria, represent conditions with the potential to cause false positive results, which significantly compromises their specificity. Conclusion: The performance of immunoassays was only moderate, affected by the duration and clinical severity of the disease. Absence of discriminatory power between IgM/IgA and IgG has also been demonstrated, which prevents the use of acute phase antibodies for decisions on social isolation.