Characterization of antibody response in asymptomatic and symptomatic SARS-CoV-2 infection

Abstract

SARS-CoV-2 pandemic is causing high morbidity and mortality burden worldwide with unprecedented strain on health care systems. To elucidate the mechanism of infection, protection, or rapid evolution until fatal outcome of the disease we performed a study in hospitalized COVID-19 patients to investigate the time course of the antibody response in relation to the outcome. In comparison we investigated the time course of the antibody response in SARS-CoV-2 asymptomatic subjects. Study results show that patients produce a strong antibody response to SARS-CoV-2 with high correlation between different viral antigens (spike protein and nucleoprotein) and among antibody classes (IgA, IgG, and IgM and neutralizing antibodies). The peak is reached by 3 weeks from hospital admission followed by a sharp decrease. No difference was observed in any parameter of the antibody classes, including neutralizing antibodies, between subjects who recovered or with fatal outcome. Only few asymptomatic subjects developed antibodies at detectable levels.

Serum Neutralizing Activity against B.1.1.7, B.1.351, and P.1 SARS-CoV-2 Variants of Concern in Hospitalized COVID-19 Patients

“…At discharge/decease, all patients showed neutralizing antibody against the wt strain, although a decline in titer was observed as deeply described elsewhere [23]. When tested against B.1.1.7, one patient (2.4%) was found negative.…”

“…In this study, we evaluated the neutralizing activity against B.1.1.7, P.1, and B.1.351 VOCs in a panel of human serum samples from hospitalized patients infected by SARS-CoV-2 between March and May 2020 during the first wave of the pandemic in Italy [ 23 ].…”

“…Sera of 42 COVID-19 patients (35 recovered and 7 with fatal outcome), hospitalized at Humanitas Gavazzeni (Bergamo, Italy) during the first epidemic wave that occurred in Italy between March and May 2020, were included in the present study. Subject characteristics and study procedures were described in detail elsewhere (approval number 17373—Ethics Committee of the University of Siena; approval number 17/20—Ethics Committee of Humanitas Gavazzeni) [ 23 ].…”

“…For the purpose of the present study, sera available for each patient at three time points were selected: the hospital admission sample (baseline), the sample showing the highest neutralizing antibody titer against 2019-nCov/Italy-INMI1 strain (hereafter referred to as wild-type (wt) strain) found in the previous study [ 23 ] and defined as “peak”, and the last sample available during hospital stay. For 22 patients, the “peak” sample was the last sample available during the hospital stay.…”

Reduced seroconversion in children compared to adults with mild COVID-19

“…Results: Among 108 SARS-CoV-2 PCR-positive participants, 57 were children (median age: 4, IQR 2-10) and 51 were adults (median age: 37, IQR [34][35][36][37][38][39][40][41][42][43][44][45]. Using three established serological assays, a lower proportion of children seroconverted compared with adults [20/54 (37.0%) vs 32/42 (76.2%); (p<0.001)].…”