1. Persistence of Neutralizing Antibodies to SARS-CoV-2 in First Wave Infected Individuals at Ten Months Post-Infection: The UnIRSA Cohort Study
- Author
-
Gloria Griffante, Shikha Chandel, Daniela Ferrante, Valeria Caneparo, Daniela Capello, Valentina Bettio, Cinzia Borgogna, Chiara Aleni, Salvatore Esposito, Andrea Sarro, Alessandra Vasile, Marco Comba, Tommaso Testa, Gianmarco Cotrupi, Marco De Andrea, Sara Bortoluzzi, and Marisa Gariglio
- Subjects
SARS-CoV-2 ,COVID-19 ,neutralizing humoral response ,Microbiology ,QR1-502 - Abstract
Longitudinal mapping of antibody-based SARS-CoV-2 immunity is critical for public health control of the pandemic and vaccine development. We performed a longitudinal analysis of the antibody-based immune response in a cohort of 100 COVID-19 individuals who were infected during the first wave of infection in northern Italy. The SARS-CoV-2 humoral response was tested using the COVID-SeroIndex, Kantaro Quantitative SARS-CoV-2 IgG Antibody RUO Kit (R&D Systems, Bio-Techne, Minneapolis, USA) and pseudotype-based neutralizing antibody assay. Using sequential serum samples collected from 100 COVID-19 recovered individuals from northern Italy—mostly with mild disease—at 2 and 10 months after their first positive PCR test, we show that 93% of them seroconverted at 2 months, with a geometric mean (GeoMean) half-maximal neutralization titer (NT50) of 387.9. Among the 35 unvaccinated subjects retested at 10 months, 7 resulted seronegative, with an 80% drop in seropositivity, while 28 showed decreased anti-receptor binding domain (RBD) and anti-spike (S) IgG titers, with a GeoMean NT50 neutralization titer dropping to 163.5. As an NT50 > 100 is known to confer protection from SARS-CoV-2 re-infection, our data show that the neutralizing activity elicited by the natural infection has lasted for at least 10 months in a large fraction of subjects.
- Published
- 2021
- Full Text
- View/download PDF