SARS-CoV-2 infection induces sustained humoral immune responses in convalescent patients following symptomatic COVID-19
Authors:J. Wu et al.
Key Words:antibody response
Symptomatic COVID-19 patients exhibit an early and rapid IgM and IgG-S/N response peaking at week 3-5, followed by contraction phase where IgM disappears below detection level around week 10-13, whilst IgG-S/N stabilizes at relative high levels for at least six months after disease onset.
SARS-CoV-2 is controlled in COVID-19 patients with high levels of IgM-S/N and IgG-S/N at early time points of disease.
IgG-RBD-S titers correlated closely with the capacity to neutralize SARS-CoV-2
The authors have quantified IgM and IgG antibodies recognizing the SARS-CoV-2 receptor-binding domain (RBD) of the spike (S) or the nucleocapsid (N) protein, and neutralizing antibodies during a period of six months following COVID-19 disease onset in 349 symptomatic COVID-19 patients of which 17 patients were sampled repetitively. IgM-S reached a peak of 94% at week 5 and then rapidly decreased to 0% at week 13. IgM-N a peak of 72% at week 3 and undetectable at week 10. IgG-S 97% at week 3 and remained relative high until week 26. IgG-N rose rapidly to 87% of the patients at week 2 and stayed at very high levels thereafter. Significant higher IgG S/N responses were observed in patients with non-severe symptoms at week 2. High neutralizing activity was only found in conjunction with high IgG-S titers, and not in plasma with high IgG-N titers or unilateral IgM responses.
Impact for SARS-CoV2/COVID19 research efforts
Understanding the immune response to SARS-CoV2/COVID19
In vitro study
Patient Case study
Strengths and limitations of the paper
Novelty: One of many recent papers longitudinally analysing antibody levels following SARS-CoV-2 infection (e.g. Long et al. Nat Med 2020, Wajnberg et al. 2020; Seow et al. 2020, and Iyer et al.) but follows patients the longest (up to 26 weeks post symptom onset).
Standing in the field:How long-lasting antibody levels are post infection is currently a matter of scientific debate (Iyer et al; J. Seuw et al.)
Viral model used:Strain BetaCoV/Wuhan/WIV04/2019, National Virus Resource Center number: IVCAS 6.7512 was used to test neutralization capacity of patient plasma.
Translatability:This preprint shows that anti-viral antibody levels in symptomatic COVID-19 patients seems to follow a prototypical progression with an early expansion phase peaking around week 3, followed by an contraction phase after which IgM disappears below detection levels at week 10-13 and a sustained memory phase for IgG up to end of study at 26 weeks. This has important implications both for the design of effective vaccines and long-term protective immunity following primary infection.
They only focus on symptomatic patients, similar to another recent preprint (Iyer et al. 2020).
As noted by the authors, due to restrictions samples at 9-11 weeks were limited and not all samples could be assessed for their neutralizing activity
Only data of 15 donors that were repetitive sampled was used, in contrast to J. Seuw et al. that sampled 65 RT-qPCR confirmed SARS-CoV-2-infected individuals over sequential time points.
No data on IgA that is also correlated to protective immunity against SARS-CoV-2.
As shown in Figure 1D IgG Ab levels continuously decline albeit at a slow rate. We feel that to conclude that these titers ‘stabilize’ a stop in declination should be observed and we rather conclude that these IgG titers wane off slow but not stabilise.