One year on: persistence of protective antibodies and significantly reduced risk of reinfection

In connection with the SEROCoV-HUS study led by Professor Samira Fafi-Kremer (University Hospital of Strasbourg (HUS) – University of Strasbourg – INSERM UMR1109), the team at Strasbourg Regional University Hospital, in collaboration with the Institut Pasteur, monitored 1,309 hospital staff – 393 who had had a mild form of SARS-CoV-2 and 916 who had not contracted the infection – for one year. The scientists demonstrated that in those who had tested positive for COVID-19, the antibodies directed against the virus spike protein (anti-S) fell more quickly in men than in women, but that they persisted in nearly everyone until 13 months after infection. After administration with a single vaccine dose, the rate of antibodies increased significantly, regardless of the pre-vaccine rate and the type of vaccine administered. A comparison of the two cohorts demonstrated that the incidence of reinfection was reduced by 96.7% in convalescent COVID-19 patients.

These results demonstrate the long-term persistence of anti-S antibodies, which can help protect against reinfection. A single-dose vaccination strengthens protection against variants by significantly increasing protective antibody titers. Evaluating the kinetics of anti-SARS-CoV-2 antibodies is vital in predicting levels of protection against reinfection and the durability of vaccine protection.

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