Serologic responses to SARS-CoV-2 infection among hospital staff with mild disease in eastern France

Abstract

Background The serologic response of individuals with mild forms of SARS-CoV-2 infection is poorly characterized. Methods Hospital staff who had recovered from mild forms of PCR-confirmed SARS-CoV-2 infection were tested for anti-SARS-CoV-2 antibodies using two assays: a rapid immunodiagnostic test (99.4% specificity) and the S-Flow assay (~99% specificity). The neutralizing activity of the sera was tested with a pseudovirus-based assay. Findings Of 162 hospital staff who participated in the investigation, 160 reported SARS-CoV-2 infection that had not required hospital admission and were included in these analyses. The median time from symptom onset to blood sample collection was 24 days (IQR: 21–28, range 13–39). The rapid immunodiagnostic test detected antibodies in 153 (95.6%) of the samples and the S-Flow assay in 159 (99.4%), failing to detect antibodies in one sample collected 18 days after symptom onset (the rapid test did not detect antibodies in that patient). Neutralizing antibodies (NAbs) were detected in 79%, 92% and 98% of samples collected 13–20, 21–27 and 28–41 days after symptom onset, respectively ( P = 0.02). Interpretation Antibodies against SARS-CoV-2 were detected in virtually all hospital staff sampled from 13 days after the onset of COVID-19 symptoms. This finding supports the use of serologic testing for the diagnosis of individuals who have recovered from SARS-CoV-2 infection. The neutralizing activity of the antibodies increased overtime. Future studies will help assess the persistence of the humoral response and its associated neutralization capacity in recovered patients. Fundings The funders had no role in study design, data collection, interpretation, or the decision to submit the work for publication.

Clinical performance of four immunoassays for antibodies to SARS-CoV-2, including a prospective analysis for the diagnosis of COVID-19 in a real-life routine care setting

“…However, early serology sampling does not explain the relative lack of agreement with COVID-19 diagnosis for Euroimmun IgG (19/21), Abbott IgG (16/21), Wantai Ab (19/21), and DiaPro IgG confirmation assay (20/21) in routine care setting. Similar observations have been made in populations of healthcare professionals, with false negative rates ranging from 1 % [ 27 ] to 20 % [ [28] , [29] , [30] ] several weeks after disease. This could be due to the high proportion of patients with mild COVID-19, resulting in low rates of seroconversion [ 28 ].…”

Anti-spike, Anti-nucleocapsid and Neutralizing Antibodies in SARS-CoV-2 Inpatients and Asymptomatic Individuals

“…As other groups, we report that COVID-19 patients generate variable levels of NAbs that reach a plateau 2 weeks postsymptom onset (Fafi-Kremer et al, 2020;Liu et al, 2020;Ni et al, 2020;Robbiani et al, 2020;Wölfel et al, 2020;Wu et al, 2020a). Our results also indicate that the SARS-CoV-2 does not induce a prolonged NAb response since we observed a drop of the NAb titer for several patients a few weeks after infection.…”

A comparison of four serological assays for detecting anti–SARS-CoV-2 antibodies in human serum samples from different populations

“…The short time frame of the sampling also allowed us to compare the performance of the four different serological assays at a given date and within a limited geographical region. We recently reported that among a cohort of 160 hospital staff in Strasbourg (France) with mild symptoms who were all positive by RT-qPCR for SARS-CoV-2 infection, a rapid immunodiagnostic commercial test detected antibodies in 153 (95.6%) of these samples and the S-Flow assay detected antibodies in 159 (99.4%) of these samples ( 26 ). The sensitivity of the S-Flow assay is thus >99%.…”