Durability of Antibody Responses to SARS-CoV-2 Infection and Its Relationship to Disease Severity Assessed Using a Commercially Available Assay

Abstract

Background: Assessing the humoral immune response to SARS-CoV-2 is crucial for inferring protective immunity from reinfection and for assessing vaccine efficacy. Data regarding the durability and sustainability of SARS-CoV-2 antibodies are conflicting. In this study, we aimed to determine the seroconversion rate of SARS-CoV-2 infection in a cohort of reverse-transcriptase polymerase chain reaction (RT–PCR)-confirmed SARS-CoV-2 infections and the antibody dynamics, durability, and the correlation of antibody titers with disease severity using the commercially available SARS-CoV-2 anti-spike (S1/S2) protein.Methods: A total of 342 subjects with PCR-confirmed COVID-19 were enrolled. A total of 395 samples were collected at different time points (0–204) after the onset of symptoms or from the day of positive PCR in asymptomatic patients. Demographics, clinical presentation and the date of PCR were collected. All samples were tested using the automated commercial chemiluminescent system (DiaSorin SARS-CoV-2 S1/S2 IgG) on the LIAISONXL® platform (LIAISON).Results: The seroconversion rate for samples collected 14 days after the onset of infection was much higher than that for samples collected before 14 days (79.4% vs. 39.4%). The rate of seroconversion in symptomatic participants (62.1%) was similar to that of asymptomatic participants (56.1%) (p = 0.496). The IgG titer distribution was also similar across both groups (p = 0.142), with a median IgG level of 27.86 AU/ml (3.8–85.5) and 15 AU/ml (3.8–58.85) in symptomatic and asymptomatic participants, respectively. However, IgG titers were significantly higher in ICU patients, with a median of 104 AU/ml (3.8–179) compared to 34 AU/ml (3.8–70) in the non-ICU participants (p < 0.0001). Furthermore, the median time to seroconversion occurred significantly faster in ICU patients than in non-ICU participants (19 versus 47 days) (P < 0.0001). IgG titers were also higher in subjects ≥50 years compared to those <50 years (p < 0.009), male compared to female (p < 0.054) and non-Saudi compared to Saudi (p < 0.003). Approximately 74% of all samples tested beyond 120 days were positive.Conclusion: Antibodies can persist in circulation for longer than 4 months after COVID-19 infection. The majority of patients with COVID-19 mounted humoral immune responses to SARS-CoV-2 infection that strongly correlated with disease severity, older age and male gender. However, the population of individuals who tested negative should be further evaluated.

Household Transmission of SARS-CoV-2 and Long-term Immunity in Children: A Prospective Study in Northern Spain

“…15,21,22 However, some studies reported that the antibody titers were only significantly higher in those patients with severe disease. 10,11 In our study, the median IgG titers were similar among symptomatic and asymptomatic patients for both (Spike protein and Nucleocapsid) assays. Accordingly, the presence of symptoms in children may not influence the antibody response, even though, these results should be interpreted carefully, as none of our symptomatic patients had a severe disease.…”

“…Most reports suggest that the titers of antibodies against SARS-CoV-2 decline over time after COVID-19 infection. 10,23 Recent studies have shown that SARS-CoV-2 antibodies remained detectable 8, 10, or 12 months after infection. [24][25][26] In our study, the titers of antibodies decreased during the follow-up but there were no cases of seroreversion, contrary to the National seroepidemiologic study (ENE-COVID), which found a seroreversion of 14.4% between April and June 2020.…”

“…There is evidence that COVID-19 patients with severe disease develop a greater antibody response than those with mild or asymptomatic disease. 10,11 Antibody titers and, hence, the level of protection have been a matter of concern since children typically have mild disease. However, most of the available data on long-term immunity against SARS-CoV-2 are from adults only, and few studies have compared antibody titers between symptomatic and asymptomatic children.…”

Rapid, early, and potent Spike-directed IgG, IgM, and IgA distinguish asymptomatic from mildly symptomatic COVID-19 in Uganda, with IgG persisting for 28 months

“…However, the dynamics of the anti-SARS-CoV-2 antibody response and persistence after infection are still debatable and have primarily been studied in the context of more severe disease, which is uncommon in African patients. While antibody persistence was associated with severe disease, comparable seropositivity was reported between symptomatic and asymptomatic individuals in some contexts (23,24) but not in others (25). Mild COVID-19 disease has been linked to a weaker humoral response, raising fears of faster waning of immunity.…”

Clinical and immunological features associated to the development of a sustained immune humoral response in COVID-19 patients: Results from a cohort study

“…Nearly all patients with COVID-19 develop a humoral antiviral immune response ( 6 ). The magnitude of the humoral immune response is strongly correlated with the disease severity ( 7 ) and the duration of active infection ( 8 ), highlighting the importance of the initial antiviral response in the development of sustained humoral immunity. A prolonged and severe COVID-19 is the clinical consequence of a disturbed adaptive and innate antiviral immune response.…”