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.
【저자키워드】 COVID-19, SARS-CoV-2, neutralizing humoral response, 【초록키워드】 neutralizing antibody, public health, Vaccine development, immune response, pandemic, antibody, Infection, Italy, SARS-CoV-2 immunity, Neutralizing activity, Cohort, IgG antibody, RBD, pseudotype, Re-infection, Seropositivity, Mild, USA, PCR test, natural infection, longitudinal, First wave, Critical, SARS-CoV-2 IgG, seronegative, Anti-spike, Mild disease, longitudinal analysis, humoral, geometric mean, subject, individual, fraction, binding domain, neutralization titer, Bio-Techne, IgG titers, R&D Systems, serum sample, first positive, performed, were infected, collected, seroconverted, subjects, elicited, geometric, was tested, 【제목키워드】 Wave, individual, Month,