SARS-CoV-2 neutralizing antibodies in patients with varying severity of acute COVID-19 illness

Abstract

In order to support vaccine development, and to aid convalescent plasma therapy, it would be important to understand the kinetics, timing and persistence of SARS-CoV2 neutralizing antibodies (NAbs), and their association with clinical disease severity. Therefore, we used a surrogate viral neutralization test to evaluate their levels in patients with varying severity of illness, in those with prolonged shedding and those with mild/asymptomatic illness at various time points.Patients with severe or moderate COVID-19 illness had earlier appearance of NAbs at higher levels compared to those with mild or asymptomatic illness. Furthermore, those who had prolonged shedding of the virus, had NAbs appearing faster and at higher levels than those who cleared the virus earlier. During the first week of illness the NAb levels of those with mild illness was significantly less (p=0.01), compared to those with moderate and severe illness. At the end of 4 weeks (28 days), although 89% had Nabs, 38/76 (50%) in those with >90 days had a negative result for the presence of NAbs. The Ab levels significantly declined during convalescence (>90 days since onset of illness), compared to 4 to 8 weeks since onset of illness. Our data show that high levels of NAbs during early illness associated with clinical disease severity and that these antibodies declined in 50% of individuals after 3 months since onset of illness.

Transmission dynamics, clinical characteristics and sero-surveillance in the COVID-19 outbreak in a population dense area of Colombo, Sri Lanka April- May 2020

“…Inhibition percentage � 25% in a sample was considered as positive for Nabs. We have validated this in the Sri Lanka population and in patients with SARS-CoV2 previously [11].…”

“…In this study, to determine infection with the SARS-CoV-2 virus, we also assessed the SARS-CoV-2 specific total antibodies and Nabs. Nabs have shown to decay with time, especially in those with mild or asymptomatic infection [11]. Therefore, this shows while the total Abs persist for longer the Nabs appear to decay faster in mild and asymptomatic individuals.…”

Sensitivity and Specificity of Two WHO Approved SARS-CoV2 Antigen Assays in Detecting Patients with SARS-CoV2 Infection

“…Individuals infected with the SARS-CoV2 virus may shed virus for a prolonged period [13,14], but are often thought to shed dead, or non-culturable virus [15,16]. The appearance of neutralizing antibodies are thought to associate with the presence of non-culturable and therefore, virus particles that are noninfectious [15].…”

Immune Responses to a Single Dose of the AZD1222/Covishield Vaccine at 16 Weeks in Individuals in Sri Lanka

“…The surrogate virus neutralization test (sVNT) (10), which measures the percentage of inhibition of binding of the RBD of the S protein to recombinant ACE2 (10) (Genscript Biotech, Piscataway, NJ), was carried out according the manufacturer's instructions as previously described by us (11). Inhibition percentage $25% in a sample was considered positive for ACE2 receptorblocking Abs.…”

“…We used the sVNT to determine the presence of ACE2 receptorblocking Abs in a subcohort of the above individuals (n 5 69). A percentage inhibition of 25% was considered a positive result as previously described (11). A total of 51 of 69 (73.9%) of individuals had ACE2 receptorblocking Abs above the cutoff value.…”