Table 6.

Humoral immune response to SAR-CoV-2 infection according to disease phenotype

Author	Population	Method	IgG	IgM	IgA	Neutralisation assay	RoB
Wang et al50	23 COVID-19 vs 48 HD	ELISA*	↑ at D10–15 after onset Remained ↑ for at least for 6W HD: no Abs detected	SEVERE: ↑ within W1-2 and ↓ after W4 MILD: Most patients negative up to W4 HD: no Abs detected	ND	73.9% of patients generated NAb Higher NAb titres in severe vs mild	Unclear
Xiang et al53	85 COVID-19 vs 60 HD	ELISA†	↑ at D11-12 after onset Remained ↑ for ≥30 HD: 5% positivity	↑ at D9 after onset, Remained ↑ for ≥30D HD: No Abs	ND	ND	Unclear
Zhao et al51	173 COVID-19	ELISA‡	↑ at D14 (median)	↑ at D12 (median)	ND	ND	Unclear
Xie et al52	56 COVID-19	CLIA§	↑ in W1 Remained ↑ for at least 41D, even after the resolution of infection	↑ in W1 and ↓ at W4-5	ND	ND	Unclear
Zhou et al54	52 COVID-19	CLIA*	↑ in W1 100% patients positive at D28 Remained ↑ up to D54	↑ in W1 and peak at W4 (77% of patients)	ND	ND	Unclear

*Antigen not specified.

†Recombinant nucleocapsid protein.

‡IgM: receptor binding domain of the spike protein; IgG: a recombinant nucleoprotein.

§Envelope (E) protein and nucleocapsid (N) protein.

D, day; HD, healthy donor; M, month; NAb, neutralising antibodies; ND, not detailed; RoB, risk of bias; W, week.