A systematic review and meta-analysis of the IgA seroprevalence in COVID-19 patients: Is there a role for IgA in COVID-19 diagnosis or severity?

Nowadays, Coronavirus disease (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is one of the most important health problems. The dynamics and nature of humoral responses are relevant to determine the efficacy of both, diagnostic tests and developed vaccines. Since the role of IgA in the COVID-19 disease is not fully understood, we have systematically reviewed the scientific literature on antibody IgA immunity to SARS-CoV-2 to determine if IgA could be useful as a diagnostic tool or as a biomarker of severity. We systematically reviewed 736 abstracts and identified 38 manuscripts relevant to include in the meta-analysis. The seroprevalence of IgA in SARS-CoV-2 PCR (+) confirmed patients was 86.47% (CI: 5.27–178.21). Furthermore, we found out that IgA can be produced on the first days of infection (10 days) and IgA is detected until 75 days after symptomatic onset in some studies. We also observe that IgA production is stronger in severe patients compared with mild or asymptomatic patients. Our research noticed a possible association between IgA and protection; however, the possible role of IgA as a biomarker of protection or severity remains unclear.