Virtually all hospital staff sampled from 13 days after the onset of mild COVID-19 symptoms in eastern France showed antibodies capable of neutralising the SARS-CoV-2 virus, a non peer-reviewed article published in medrxiv has claimed. This may be associated with immunity against further infection with the same virus, the authors have argued.
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The paper ‘Serologic responses to SARS-CoV-2 infection among hospital staff with mild disease in eastern France’ by Samira FAFI-KREMER et al, showed that neutralising antibodies were found in 91% of the individuals of the Strasbourg University Hospitals who participated in the study. 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 test and the S-Flow assay.
The authors state: “We further report that the neutralisation activity of the serum increases with time, reaching 97% four weeks after the onset of symptoms. Therefore, it is a fair assumption that the majority of individuals with mild COVID-19 generate neutralising antibodies within a month after onset of symptoms.” They go on to add: “Although not yet demonstrated, several lines of evidence suggest that the presence of neutralising antibodies may be associated with protective immunity for SARS-CoV-2 infection.”
High neutralising activity was associated with time since onset of symptoms, in subjects having a dry cough, male participants, those with a high BMI, and high blood pressure. All these characteristics remained independently associated with high neutralising activity in multivariable analysis except for high blood pressure, the paper said.
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“Antibody titres are generally higher in patients with severe or critical diseases. Interestingly, in our study, individuals with factors associated with more severe disease (e.g., male sex, high body mass index and high blood pressure), were more likely to have high titres [required volume] of neutralising antibodies compared to others,” the authors observed. Further, they called for future studies to characterise the beneficial or detrimental role of specific antibodies in COVID-19 patients and the minimal titre required for protection.