Heterogeneity of humoral response patterns in mildly symptomatic, non-hospitalized COVID-19 patients: A one-year longitudinal study

Author(s)

Andrade, Luis A. F. ; Bagno, Flavia F. ; Sergio, Sarah A. R. ; Parise, Pierina L. ; Toledo-Teixeira, Daniel A. ; Fernandes, Ana P. S. M. ; Teixeira, Santuza M. R. ; Granja, Fabiana ; Proenca-Modena, Jose Luiz ; da Fonseca, Flavio G.

• Document type: Journal article
• Source: Experimental Biology and Medicine; v. 248, n. 10, p. 9-pg., 2023-03-20.

Abstract

The duration and protectiveness of antibodies against SARS-CoV-2 in infected subjects are still uncertain; nonetheless, anti-S-specific antibodies can contribute to protective immunity against new infections. It has been described that the level of antibodies produced in COVID-19 is related to the severity of symptoms, and the majority of the humoral response studies have been conducted in hospitalized patients who have been, then, followed over time. However, about 80% of SARS-CoV-2 infections in unvaccinated people are mild to asymptomatic, and this percentage reaches more than 95% in vaccinated individuals. Therefore, understanding the long-term dynamics of the antibody responses in this predominant part of the COVID-19-affected population is essential. In this study, we followed a cohort of individuals with mild COVID-19 who did not require hospitalization. We collected blood samples at sequential times after the SARS-CoV-2-positive qRT-PCR result. From 65 recruited patients, 50 had detectable antibodies at screening. Anti-SARS-CoV-2 IgM levels peaked around two weeks post-COVID-19 diagnostics, becoming undetectable after 65 days. IgG levels reached a peak in approximately one month and remained detectable for more than one year. In contrast to the levels of anti-SARS-CoV-2, antibody neutralization potency indexes persisted over time. In this study, humoral responses in mild COVID-19 patients persisted for more than one year. This is an important long-term follow-up study that includes responses from COVID-19 patients before and after vaccination, a scenery that has become increasingly difficult to evaluate due to the growing vaccination of the world human population. (AU)

• FAPESP's process: 16/00194-8 - Pathogenesis and neurovirulence of emerging viruses in Brazil
• Grantee: José Luiz Proença Módena
• Support Opportunities: Research Grants - Young Investigators Grants
• FAPESP's process: 20/04558-0 - Characterization of intrinsic risk factors and the development of new diagnostic and treatment alternatives for COVID-19
• Grantee: José Luiz Proença Módena
• Support Opportunities: Regular Research Grants