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. Results: 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). Conclusion: 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.

Serum-IgG responses to SARS-CoV-2 after mild and severe COVID-19 infection and analysis of IgG non-responders

“…In this study, we found that almost 10% of patients with mild COVID-19 did not develop detectable anti-SARS-CoV-2 IgG in serum as evaluated by assays used in clinical practice. Previous studies have similarly failed to detect IgG antibodies in patients with mild disease [24][25][26], but due to short follow-up (less than 25-50 days) no conclusions regarding the proportion of patients who do not seroconvert have been made in the belief that antibody levels become detectable later in time. We show that despite 90 days or more PSO, not all patients develop detectable levels of IgG in these assays.…”

Antibody response to SARS-CoV-2 infection in humans: a systematic review

“…Neutralising antibody responses correlated with disease severity in all studies in which this association was tested. 7,43,49,66,76,85,87,[96][97][98] Importantly, the few studies that investigated asymptomatic cases found those individuals were considerably less likely to develop detectable serum neutralising antibody responses than cases with symptoms. With regard to age and sex, evidence was mixed and a limitation across all papers was a lack of statistical adjustment for severity.…”

“…159 Antibody titre • Ten studies reported a higher titre of neutralising antibodies in more clinically severe cases. 7,43,49,66,85,87,[95][96][97][98]…”

“…N/A • Five studies reported neutralising antibody response was positively correlated with male sex, 66,68,87,96 although it is unclear how this is related to disease severity. 49…”

A viral perspective on worldwide non-pharmaceutical interventions against COVID-19

“…3c), this finding is intriguing. Indeed, several public events resulted in large case clusters, the so-called superspreading events, that triggered epidemic bursts in France 33 , South Korea 34 or the U.S. 35 . A plausible explanation for not detecting the effectiveness of cancelling public events is that datadriven models, including ours, better capture the cumulative effect of more frequent events such as gatherings than the massive effect of much rarer events such as superspreading public events.…”