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

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.

Longitudinal Study on Seroprevalence and Immune Response to SARS-CoV-2 in a Population of Food and Retail Workers Through Transformation of ELISA Datasets

“…The impact of this study is amplified because cohort studies of highly vaccinated adults without pre-exis;ng severe health problems who were not hospitalized for COVID-19 are scarce [40,41] and because few COVID-19 studies have reported longitudinal data from sampling of the same individuals over a long period [42].…”

“…This 1.5-year longitudinal study of the humoral response elicited by vaccination and by SARS-CoV-2 infection in a cohort of 304 essential workers from food service and retail in the Québec City area continues to highlight the capacity for a decentralized approach to effectively monitor the humoral response to infection, particularly in specific, understudied populations [37]. The impact of this study is amplified because cohort studies of highly vaccinated adults without pre-existing severe health problems who were not hospitalized for COVID-19 are scarce [40,41] and because few COVID-19 studies have reported longitudinal data from sampling of the same individuals over a long period [42].…”

“…This work is part of a collective effort and stresses the importance of rapidly developing adaptable, decentralized tests for population-level immune surveillance in response to a pandemic, even before centralized testing is available [37,39]. To our knowledge, no other study has reported such an extensive 18-month longitudinal investigation during the key periods preceding and following the emergence of Omicron in a cohort of highly vaccinated food and retail workers, using both centralized and customized methods to analyze two types of immunoglobulin, three types of epitope, and antigens to three VOC [40,41], [42]. This study will inform strategies and measures to be implemented in the event of a future pandemic.…”

Impacts of Inflammatory Cytokines Variants on Systemic Inflammatory Profile and COVID-19 Severity

“…The clinical manifestations of COVID-19 differ substantially in severity, varying from asymptomatic or mildly symptomatic to severe or critical illness [ 3 , 4 ]. Among the infected individuals with symptoms, the majority presented with mild illness [ 5 – 7 ], while approximately 10% progressed to a severe or critical stage requiring intensive care or mechanical ventilation support [ 8 , 9 ]. The variation in symptoms or severity of COVID-19 might be attributed to some known risk factors, including males [ 10 ], older age [ 11 ], alcohol consumption [ 12 ], menopause [ 13 ], smoking [ 14 ], and underlying comorbidities (e.g., hypertension [ 14 , 15 ], diabetes [ 14 – 16 ], cardiovascular disease [ 14 – 16 ], chronic pulmonary disease [ 15 – 17 ], obesity [ 15 , 18 ], cancer [ 15 , 19 ], and immunodeficiencies [ 15 ]).…”