Persistence of Neutralizing Antibodies to SARS-CoV-2 in First Wave Infected Individuals at Ten Months Post-Infection: The UnIRSA Cohort Study

• Published in: Viruses Vol. 13; no. 11; p. 2270
• Main Authors: Griffante, Gloria, Chandel, Shikha, Ferrante, Daniela, Caneparo, Valeria, Capello, Daniela, Bettio, Valentina, Borgogna, Cinzia, Aleni, Chiara, Esposito, Salvatore, Sarro, Andrea, Vasile, Alessandra, Comba, Marco, Testa, Tommaso, Cotrupi, Gianmarco, De Andrea, Marco, Bortoluzzi, Sara, Gariglio, Marisa
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 12.11.2021; MDPI
• Subjects: Adult; Antibodies; Antibodies, Neutralizing - immunology; Antibodies, Viral - blood; Asymptomatic; Asymptomatic Infections; blood serum; Brief Report; Cohort analysis; Cohort Studies; Coronaviruses; COVID-19; COVID-19 - epidemiology; COVID-19 - immunology; COVID-19 - virology; COVID-19 infection; COVID-19 Serological Testing; COVID-19 Vaccines - immunology; Drug dosages; Female; Hospitalization; Humans; humoral immunity; Immune response; Immune response (humoral); Immunity; Immunity, Humoral; Immunoglobulin G; Immunoglobulin G - blood; Infections; Italy; Italy - epidemiology; Longitudinal Studies; Male; Middle Aged; neutralization; neutralizing humoral response; pandemic; Pandemics; Patients; Protein Domains - immunology; Proteins; Public health; SARS-CoV-2; SARS-CoV-2 - immunology; Seroconversion; seroprevalence; Severe acute respiratory syndrome coronavirus 2; Software; Spike Glycoprotein, Coronavirus - immunology; Vaccine Development; Italy; United States > US; COVID-19; neutralizing humoral response; SARS-CoV-2
• ISSN: 1999-4915; 1999-4915
• DOI: 10.3390/v13112270

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.