SARS-CoV-2-IgG response is different in COVID-19 outpatients and asymptomatic contact persons

Incomplete humoral response including neutralizing antibodies in asymptomatic to mild COVID-19 patients in Japan

“…This difference is considered to be due to the many asymptomatic patients who do not have any antibody. Although there are few studies including many asymptomatic individuals, a German report ( Wellinghausen et al, 2020 ) examining asymptomatic patients with a positive PCR test showed that 85% of these patients were antibody negative, and seropositivity were negatively correlated to Ct values, consistent with our results. These results indicate that a high viral load, pneumonia, and strong systemic response have important roles in the antibody production, similar to findings in Japan and Western countries.…”

“…The overall positive rate is shown in Fig. 2 B, which was significantly lower than the reported 80–100% ( Wellinghausen et al, 2020 ; Liu et al, 2020 ; Lau et al, 2020 ; Shaw et al, 2020 ; Caturegli et al, 2020 ). We also checked IgG subclass against these antigens using 10 representative serum samples.…”

“…Antibody titers against various SARS-CoV-2-derived antigens have been measured and reported to have high specificity for the Spike protein and Nucleocapsid protein (N)( Jiang et al, 2020 ), and many of the antibody tests have been developed using Spike and/or N as antigens. The serum antibody titers were reported to rise from 10-14 days after onset and peak at the third week ( Wellinghausen et al, 2020 ; Liu et al, 2020 ; Lau et al, 2020 ; Shaw et al, 2020 ; Caturegli et al, 2020 ). To measure the neutralizing titer, several procedures using live virus or pseudovirus have been developed, and it is also known that the titer of neutralizing antibody correlates to some extent with the antibodies against Spike and the N protein ( Wu et al, 2020 ; Robbiani et al, 2020 ; Okba et al, 2020 ; Wang et al, 2020 ).…”

REGN-COV2, a Neutralizing Antibody Cocktail, in Outpatients with Covid-19

“…These findings are consistent with those in other studies that have shown an association between native antibodies against SARS-CoV-2 and viral loads. 14 , 20 Overall, our findings are consistent with the hypothesis that most infected persons successfully recover because of their endogenous immune response. 21 This understanding of the natural history of Covid-19 supported our prospective hypothesis that an exogenously provided antibody cocktail would have the most benefit in patients whose own immune response had not yet been initiated, since such patients would have higher baseline viral loads and a higher likelihood of seeking additional medical treatment.…”

Comparative study of a new commercial recombinant line assay and two immunoassays for detection of SARS-CoV-2 IgG antibodies in PCR-confirmed outpatients

“…Samples were stored at 4-8°C for up to one week, then frozen at −20°C, and thawed only once. SARS-CoV-2-RT-PCR was performed with different commercial PCR assays on the cobas ® 6800 analyzer and the LightCycler ® 480II (Roche Diagnostics) targeting the envelope (E) gene, open reading frame (orf) 1, and/or the nucleocapsid gene as described previously [7]. Generally, two of the above genes were amplified.…”