Abstract

Background: Severe Coronavirus 2019 disease (COVID-19), caused by the severe acute respiratory syndrome corovavirus-2 (SARS-CoV-2), has been associated with an exacerbated immune response. Anti-SARS-CoV-2 antibodies (ab) revelated a memory response and they can play a protective role due to neutralization and viral clearance. However, antibodies can also activate the complement cascade and promote blood clots, supporting the exacerbated immune response. The aim of this study was to evaluate whether the levels of Anti-SARS-CoV-2 ab were associated with COVID-19 severity and pulmonary sequalae 6-months after acute phase.Methods: 60 COVID-19 patients were recruited from Víctor-Rios- Ruiz Hospital, 6-months after acute phase. Serum samples were collected to measure IgM and IgG Anti- SARS-CoV-2 ab levels (Nucleocapsid + Spike) using commercial CLIA assays. Pulmonary dysfunction was analysed by measuring computerised tomography (CT) scan and the diffusing capacity of the lung for carbon monoxide (DLCO) exam.Results: Antibody levels were compared between patients’ groups and increased Anti-SARS-CoV-2 IgG levels were found in patients with acute respiratory syndrome (ARDS). Then, we analysed whether the humoral response was associated with lung sequalae and increased Anti-SARS-CoV-2 IgG levels were observed in patients with abnormal CT scan, but not with impaired DLCO. No significant differences were observed for Anti-SARS-CoV-2 IgM levels regarding severity or sequelae.Conclusions: Chilean patients with severe COVID-19 produced higher IgG Anti-SARS-CoV-2 ab levels than patients with mild symptoms, possibly due to an exacerbated immune response. The increased humoral response was associated with structural lung damage but not with lung dysfunction.