Kinetics of SARS-CoV-2 specific IgM and IgG responses in COVID-19 patients

Figures & data

Table 1. Basic information of COVID-19 patients.

	Group A: non-ICU patients (n = 27)	Group B: ICU patients (n = 11)	P value
Median ages (IQR)	44.0 (32.0–56.0)	58.0 (49.0–69.5)	0.05
Gender
Female	13(48%)	1(9%)	0.03
Male	14(52%)	10(91%)	..
Median days of admission after symptom onset (IQR)
	4(3.75–7)	5(2–10.5)	0.35
Median hospital Stay days (IQR)
	19.0 (14.3–22.5)	31.0 (30.0–33.5)	<0.001
Median days of SARS-COV-2 Nucleic Acid negative after symptom onset (IQR)
	13.0 (12.0–16.3)	31.0 (22.5–32.0)	<0.001
Presenting symptoms
Fever	26(96%)	10(91%)	0.5
Cough	22(81%)	11(100%)	0.29
Shortness of breath	5(19%)	8(73%)	0.003
Anorexia	8(30%)	10(91%)	<0.001
Underlying medical disorders
None	14(52%)	5(45%)	>0.99
Hypertension	5(19%)	4(36%)	0.4
Chronic pulmonary disease	0(0%)	2(18%)	0.08
Coronary heart disease	1(4%)	0(0%)	>0.99
Chronic gastritis	2(7%)	0(0%)	>0.99
Liver cyst	1(4%)	0(0%)	>0.99
Tuberculosis	1(4%)	0(0%)	>0.99
Hyperlipidemia	1(4%)	0(0%)	>0.99
Fatty liver	1(4%)	0(0%)	>0.99
Thalassemia	1(4%)	0(0%)	>0.99
Colon cancer	1(4%)	0(0%)	>0.99
Diabetes	0(0%)	5(45%)	<0.001

IQR: Interquartile range.

Figure 1. The seropositive rates of N and S specific IgM and IgG antibody responses in non-ICU patients after symptom onset. A. The changes in seropositive rates of N-IgM, N-IgG, S-IgM and S-IgG in 27 non-ICU patients. B. The changes in seropositive rates of N-IgM + N-IgG, S-IgM + S-IgG, N-IgM + S-IgM, N-IgG + S-IgG, N-IgM + S-IgM + N-IgG + S-IgG in 27 non-ICU patients.

Table 2. Seropositive rate (%).

Weeks	N-IgM	N-IgG	S-IgM	S-IgG	N-IgM + N-IgG	S-IgM +  S-IgG	N-IgM + S-IgM	N-IgG + S-IgG	N-IgM + S-IgM + N-IgG + S-IgG
1	41.7	41.7	41.7	58.3	58.3	66.7	58.3	66.7	75.0
2	73.7	84.2	68.4	78.9	94.7	89.5	84.2	94.7	94.7
3	73.7	100.0	73.7	100.0	100.0	100.0	89.5	100.0	100.0

N-IgM: N protein specific IgM; N-IgG: N protein specific IgG; S-IgM: S protein specific IgM; S-IgG: S protein specific IgG.

Figure 2. Kinetics of N and S specific IgM and IgG responses in non-ICU patients and ICU patients. (A) N-IgM, (B) N-IgG, (C) S-IgM, (D) S-IgG responses in 7 non-ICU patients; (E) N-IgM, (F) N-IgG, (G) S-IgM, (H) S-IgG antibodies response in 11 ICU patients.

Table 3. SARS-COV-2 N and S specific IgM and IgG responses (OD450nm: mean + SD).

Weeks after onset	Patients	N		P value	S		P value	The ratio of N-IgG/S-IgG
		IgM	IgG		IgM	IgG
Week1	non-ICU (n = 14)	0.44 + 0.41	0.51 + 0.53	0.358	0.36 + 0.32	0.24 + 0.20	0.132	2.56 + 3.09
	ICU (n = 6)	0.99 + 1.03	1.31 + 1.0	0.316	0.36 + 0.21	0.23 + 0.14	0.145	6.04 + 3.50
	P value	0.061	0.020		0.500	0.481		0.025
Week2	non-ICU (n = 19)	0.51 + 0.28	1.0 + 0.69	0.004	0.42 + 0.27	0.58 + 0.49	0.112	2.87 + 3.45
	ICU (n = 15)	1.51 + 1.12	2.38 + 0.86	0.014	0.69 + 0.48	0.57 + 0.28	0.216	5.98 + 5.10
	P value	0.000	0.000		0.026	0.467		0.024
Week3	non-ICU (n = 20)	0.6 + 0.38	1.93 + 0.73	0.001	0.64 + 0.52	1.25 + 0.62	0.001	2.11 + 1.67
	ICU (n = 25)	1.50 + 1.01	2.92 + 0.52	<0.001	0.70 + 0.43	1.01 + 0.36	0.025	3.38 + 1.67
	P value	<0.001	<0.001		0.335	0.028		0.011

ICU: intensive care unit. N-IgG: N protein specific IgG; S-IgG: S protein specific IgG.

Figure 3. The correlation between N and S specific IgM and IgG responses in non-ICU patients and ICU patients. A. The correlation between S-IgG and S-IgM in non-ICU patients; B. The correlation between N-IgG and N-IgM in non-ICU patients; C. The correlation between S-IgG and S-IgM in ICU patients; D. The correlation between N-IgG and N-IgM in ICU patients. The Pearson correlation coefficient was used to measure the strength of the correlation between IgM and IgG antibodies. The correlation coefficient was calculated using Student’s t-test, a P-value < 0.05 was considered statistically significant. *, P < 0.05; **, P < 0.01; ***, P < 0.001.

Figure 4. The correlation between N and S specific IgM and IgG responses with CRP in non-ICU patients. A. The correlation between N-IgG and the reduction of CRP; B. The correlation between S-IgG and the reduction of CRP; C. The correlation between N-IgM and CRP; D. The correlation between S-IgM and CRP. The Pearson correlation coefficient was used to measure the strength of the correlation between CPR and IgM or IgG antibodies.

Figure 5. The N and S specific IgM and IgG responses in non-ICU patients and ICU patients. A. Comparison of N-IgM responses between non-ICU and ICU patients; B. Comparison of N-IgG responses between non-ICU and ICU patients; C. Comparison of S-IgM responses between non-ICU and ICU patients; D. Comparison of S-IgG responses between non-ICU and ICU patients. E. Comparison of N-IgG/S-IgG ratio between non-ICU and ICU patients. Correlation coefficient was calculated using Student’s t test, a P-value < 0.05 was considered statistically significant. *, P < 0.05; **, P < 0.01; ***, P < 0.001.