Neutralizing Antibodies Responses to SARS-CoV-2 in COVID-19 Inpatients and Convalescent Patients

Abstract

Background. COVID-19 is a pandemic with no specific antiviral treatments or vaccines. The urgent needs for exploring the neutralizing antibodies from patients with different clinical characteristics are emerging. Methods.A total of 117 blood samples were collected from 70 COVID-19 inpatients and convalescent patients. The presence of neutralizing antibody was determined with a modified cytopathogenic assay based on live SARS-CoV-2. The dynamics of neutralizing antibody levels at different with different clinical characteristics were analyzed.Results. The seropositivity rate reached up to 100.0% within 20 days since onset, and remained 100.0% till day 41-53. The total GMT was 1:163.7 (95% CI, 128.5 to 208.6), and the antibody level was highest during day 31-40 since onset, and then decreased slightly. Individual differences in changes of antibody levels were observed among 8 representative convalescent patients. In multivariate GEE analysis, patients at age of 31-60 and 61-84 had a higher antibody level than those at age of 16-30 (β=1.0518, P=0.0152; β =1.3718, P=0.0020). Patients with a worse clinical classification had a higher antibody titer (β=0.4639, P=0.0227).Conclusions. The neutralizing antibodies were detected even at the early stage of disease, and a significant response showed in convalescent patients. Moreover, changes on antibody levels ware individual specific.

Serological identification of SARS-CoV-2 infections among children visiting a hospital during the initial Seattle outbreak

“…Our assays included controls from adults with RT-PCR-confirmed infections, as well as samples from five children with confirmed infections collected at various times post symptom onset, including children from outside the study population (see "Methods-Study participants" for additional details). Neither adult nor child samples <1 week post symptom onset were seropositive by our criteria, consistent with prior reports that infected individuals generally do not become seropositive until at least a week post symptom onset [10][11][12][13][14] . However, all samples ≥1 week post symptom onset were seropositive, and in most cases, the signal greatly exceeded pre-2020 negative controls.…”

“…2a, b). While this convenience sample from children seeking medical care is unlikely to be representative of all children in Seattle, the period seroprevalence measurements for our population are similar to all-age cumulative incidence estimates for the Seattle region based on viral testing and mortality data 20,21 , given the ≈1-2-week lag between symptom onset and seroconversion [10][11][12][13][14] . In addition, the temporal dynamics of seropositivity in our study population mirrors recent viral testing-based findings that infection in Seattle area children was rare before March 2020 22 , but increased markedly in March and April 23 .…”

“…Serological assays, which detect antibodies induced by infection, provide such an approach. When interpreting these assays in a temporal context, note that individuals do not become seropositive until ≈1-2 weeks post symptom onset [10][11][12][13][14] , while PCR-based testing generally only detects viral RNA during the first few weeks after symptom onset 11,12 .…”

Laboratory testing for the diagnosis of COVID-19

“…In a systematic review of 38 studies that evaluated the sensitivity of antibody testing by time since symptom onset, IgM was detected in 23% by one week, in 58% by two weeks, and in 75% by three weeks; the corresponding detection rates for IgG were 30, 66, and 88% [ 54 ]. Other studies have suggested that the rate of positive IgG approaches 100% by 16–20 days [ 58 , 71 , 72 ]. Antibody levels are expected to reach the peak level at around three to four weeks from symptom onset.…”

SARS-CoV-2 antibodies, serum inflammatory biomarkers and clinical severity of hospitalized COVID-19 Patients

“…The copyright holder for this preprint this version posted July 24, 2020. ; https://doi.org/10.1101/2020.07.22.20159673 doi: medRxiv preprint 5 infection is a major concern [6,15,16]. In this context, higher antibody titers, either neutralizing or not, have been reported to be present in patients developing severe forms of COVID-19 when compared to mildly symptomatic individuals who did not require hospitalization [17][18][19][20][21][22][23]. Here, we aimed to explore the potential relationship between the magnitude of SARS-CoV-2 antibodies binding to RBD and NtAb targeting the S protein with the severity of COVID-19 in a cohort of hospitalized patients.…”