Persistence assessment of SARS-CoV-2-specific IgG antibody in recovered COVID-19 individuals and its association with clinical symptoms and disease severity: A prospective longitudinal cohort study

Abstract

Background Antibodies play an important role in neutralizing invading pathogens and protecting the host against re-infection. Thus, the accurate assessment of antibodies during a pandemic can provide important evidence for monitoring pathogen exposure, understanding the role of antibodies in protective immunity, and helping vaccine development. Methods In this study, 96 west Iranian recovered COVID-19 subjects were recruited and, based on clinical symptoms and disease severity, categorized into three different groups: mild, moderate, and severe. In addition, the presence and dynamic change of SARS-CoV-2-specific IgG antibody three, four-, and six months post symptom onset (PSO) were measured. Also, the association between IgG antibody titer with clinical symptoms and disease severity was examined. Results Although in real-time RT-PCR-positive samples negative IgG antibody results were found, most subjects mount humoral immune responses that could raise a robust SARS-CoV-2-specific IgG antibody. Furthermore, this antibody persisted in the serum of most recovered COVID-19 subjects at least six months PSO and demonstrated little to no decrease. Also, specific IgG antibody titer was strongly correlated with clinical symptoms and disease severity. Conclusions These results provide an insight into the presence and persistence of the SARS-CoV-2-specific IgG antibody. Although serological tests could not be used as the primary diagnostic test, they may support real-time RT-PCR results. Also, they could be used for diagnosing COVID-19 subjects tested later outside of the optimal period. Thus, the SARS-CoV-2-specific IgG antibody is an excellent marker of COVID-19 infection or vaccination and provides an additional diagnostic tool for verifying results and helps monitor and control COVID-19 spread.

Persistence of Antibody Responses to the SARS-CoV-2 in Dialysis Patients and Renal Transplant Recipients Recovered from COVID-19

“…Our findings in the overall cohort of immunodepressed subjects seem to confirm such heterogeneity in humoral immune responses that tends to decline over time. A longer antibody persistence and higher initial SARS-CoV-2 S1/S2 IgG titers are associated with the severity of the disease, in agreement with evidence from non-renal patients [43]. In our experience, some patients had no detectable antibodies (SARS-CoV-2 S1/S2 IgG < 15 AU/mL) from the first quantitative test, thus the downward steps in the first part of the Kaplan-Meier survival curve should not be interpreted as an early antibody loss, but more feasibly as a lack of development.…”

Immune evasion and chronological decrease in titer of neutralizing antibody against SARS-CoV-2 and its variants of concerns in COVID-19 patients

“…Next, we performed a multivariate analysis using the clinical parameters that correlated with the titers of neutralizing antibodies. As shown in Table 3 , disease severity, highest CRP level, and highest LD level were identified as the independent variables correlating with the titers of neutralizing antibodies, consistent with the previous studies [ 22 , 23 , 25 ].

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The kinetics and predictors of anti‐SARS‐CoV‐2 antibodies up to 8 months after symptomatic COVID‐19: A Czech cross‐sectional study

“… 35 Most symptoms are organ‐specific, so a higher number of symptoms usually means a higher number of affected body systems, which can be reflected in subsequent IgG antibody responses, as in the case of documented lung involvement. 36 …”

“…35 Most symptoms are organ-specific, so a higher number of symptoms usually means a higher number of affected body systems, which can be reflected in subsequent IgG antibody responses, as in the case of documented lung involvement. 36 T A B L E 3 Proportional hazards (Cox) regression expressing the chance of seronegativity (or seropositivity as an inverse value) with respect to the interval between symptom onset and serology testing. Viral shedding lasts considerably longer in symptomatic patients compared to asymptomatic patients.…”