Seroprevalence of anti‐SARS‐CoV‐2 antibodies in COVID‐19 patients and healthy volunteers up to 6 months post disease onset

Abstract

SARS-CoV-2 has emerged as a human pathogen, causing clinical signs, from fever to pneumonia-COVID-19-but may remain mild or asymptomatic. To understand the continuing spread of the virus, to detect those who are and were infected, and to follow the immune response longitudinally, reliable and robust assays for SARS-CoV-2 detection and immunological monitoring are needed. We quantified IgM, IgG, and IgA antibodies recognizing the SARS-CoV-2 receptor-binding domain (RBD) or the Spike (S) protein over a period of 6 months following COVID-19 onset. We report the detailed setup to monitor the humoral immune response from over 300 COVID-19 hospital patients and healthcare workers, 2500 University staff, and 198 post-COVID-19 volunteers. Anti-SARS-CoV-2 antibody responses follow a classic pattern with a rapid increase within the first three weeks after symptoms. Although titres reduce subsequently, the ability to detect anti-SARS-CoV-2 IgG antibodies remained robust with confirmed neutralization activity for up to 6 months in a large proportion of previously virus-positive screened subjects. Our work provides detailed information for the assays used, facilitating further and longitudinal analysis of protective immunity to SARS-CoV-2. Importantly, it highlights a continued level of circulating neutralising antibodies in most people with confirmed SARS-CoV-2.

Long-term kinetics of anti-SARS-CoV-2 antibodies in a cohort of 197 hospitalized and non-hospitalized COVID-19 patients

“…The difference was higher if considering weeks 17 to 32 ( Figure 1B). Other studies also reported higher levels of antibodies in patients with more severe disease [2,[14][15][16]. Of the 21 patients for which at least three independent blood drawn were available for a minimal follow-up period of 7 weeks, a decrease in antibody titer was observed for 4 non-hospitalized patients out 10 (40%).…”

“…A sustained antibody response against the receptor-binding domain (RBD) antigen, as assessed by the Wantai and the Siemens total antibody assays, was also observed up to 4 months [15,17]. A decrease in anti-RDB IgG and anti-spike IgG levels was similarly observed over a period of up to 5 months in recent reports [6,14,15,18,19]. A significant decrease in sensitivity was also found using the Abbott assay (NCP IgG), in studies with up to 4 months of followup [15,17].…”

“…The fact that anti-NCP assays have the lowest neutralizing capacity could be expected, as neutralizing antibodies are directed to the spike protein responsible for enabling cell entry. Indeed, a strong correlation between levels of anti-RBD or anti-spike antibodies and neutralizing capacity has been found in independent evaluations [5,6,14,19,24]. Neutralizing capacity remained robust from 1 to 5 months in several studies [14,19,20], although modest declines at 3-5 months were observed by Wajnberg et al and Isho et al [5,18].…”

“…Indeed, a strong correlation between levels of anti-RBD or anti-spike antibodies and neutralizing capacity has been found in independent evaluations [5,6,14,19,24]. Neutralizing capacity remained robust from 1 to 5 months in several studies [14,19,20], although modest declines at 3-5 months were observed by Wajnberg et al and Isho et al [5,18]. Other studies however observed a significant decrease of 2 to 4-fold, in neutralizing capacity up to 3 months [16,17,[25][26][27].…”

Evaluating SARS-CoV-2 Seroconversion Following Relieve of Confinement Measures

“…In moderate and severe COVID-19 disease women have been found to have higher antibody titers than men (27)(28)(29)(30). However, this does not appear to be the case in asymptomatic and mild disease (31,32). In agreement, our study group, composed overwhelming of asymptomatic individuals, did not provide any differences in IgG end-point titers between females and males ( Figure 2C).…”