Enhanced immunity against SARS-CoV-2 in returning Chinese individuals

Figures & data

Table 1. Demographic and epidemiological information of 272 subjects (235 returning Chinese individuals, 37 foreigners).

	N (%)		N (%)
Sex		Smoking status
Male	210 (77.2%)	Never smoker	183 (67.3%)
Female	62 (22.8%)	Ever smoker	27 (9.9%)
		Current smoker	62 (22.8%)
Age (years)	37.77 ± 10.08^a
≤29	52 (19.1%)	Alcohol consumption
30–39	90 (33.1%)	Never drinker	101 (37.1%)
40–49	60 (22.1%)	Ever drinker	104 (38.2%)
≥50	31 (11.4%)	Current drinker	67 (24.6%)
Height (centimeters)	169.44 ± 7.38^a	COVID-19
		Yes	78 (28.7%)
Weight (kilograms)	71.69 ± 18.10^a	No	194 (71.3%)
Medical history of chronic diseases		Number of COVID-19 infections
Yes	14 (5.1%)	0	194 (71.3%)
No	258 (94.9%)	1	69 (25.4%)
		2	8 (2.9%)
Comorbidities		3	1 (0.4%)
Hypertension	6 (2.2%)
Diabetes	4 (1.5%)	SARS-CoV-2 vaccine dose
Cardiovascular disease	1 (0.4%)	0	21 (7.8%)
Other diseases	5 (1.8%)	1	2 (0.7%)
		2	49 (18.0%)
Time of last vaccination		3	166 (61.0%)
2020	5 (1.8%)	4	34 (12.5%)
2021	121 (44.5%)
January-April 2022	61 (22.5%)	Specimen Collection
May-August 2022	33 (12.1%)	Yes	108 (39.7%)
September-December 2022	31 (11.4%)	No	164 (60.3%)
Unknown	21 (7.7%)

^aAge, height, and weight were normally distributed and are presented as the means ± standard errors (SEM).

Table 2. SARS-CoV-2 N and S proteins and neutralizing antibodies by ELISA.

	N	Positive (%)	Concentration	IQR
NAb (IU/mL)
primary	17	17 (100.0)	1264.16	518.45 ~ 4525.83
homologous booster	68	38 (100.0)	899.35	251.98 ~ 3673.31
heterologous booster	23	23 (100.0)	5599.32	1392.12 ~ 17855.65
N protein (ng/ml)	108	19 (17.6)	0.97	0.76 ~ 1.61
S protein (pg/ml)	108	0	/

Concentration: The data are shown as the medians; IQR: interquartile range; primary: only one or two doses of COVID-19 vaccine; homologous booster: two inactivated COVID-19 vaccines with an inactivated booster; heterologous booster: two inactivated COVID-19 vaccines with an mRNA/adenovirus vector/recombinant protein booster.

Figure 1. NAb titers of participants with (a) primary, (b) homologous booster and (c) heterologous booster vaccination against the prototype virus and a variety of omicron variants of concern (VOCs).

Neutralizing antibody titers against the prototype virus and 4 Omicron VOCs, BA.5, BF.7, BQ.1, and XBB.1, were tested for in the serum of 108 participants. Positive rate. the number of participants with NAb titers ≥ 4 in the primary/homologous booster/heterologous booster vaccination group; GMT. geometric mean titer.

Figure 2. SARS-CoV-2-specific memory T-cell (MTC) responses in participants (N = 33) with primary, homologous booster and heterologous booster vaccination. (a) Number of specific IFN-γ-secreting T cells. (b) Number of specific IL-2-secreting T cells. (c) The spots from sample 93.

The highest spot value observed from all of the negative controls was used as a cutoff (IFN-γ, 8; IL-2, 4).

Table 3. Univariate analysis of factors related to NAb titers for SARS-CoV-2.

	Prototype	Omicron BQ.1	Omicron XBB.1	Omicron BA.5	Omicron BF.7
Sex
Male	0.313 (0.577)	0.104 (0.748)	0.000 (0.991)	0.000 (0.995)	0.106 (0.745)
Female
Age (years)
≤29	1.880 (0.137)	0.297 (0.827)	0.412 (0.745)	0.062 (0.980)	0.334 (0.801)
30–39
40–49
≥50
Height (centimeters)	3.884 (0.051)	0.724 (0.397)	0.194 (0.660)	2.946 (0.089)	2.227 (0.139)
Weight (kilograms)	2.094 (0.151)	0.410 (0.524)	0.011 (0.916)	1.717 (0.193)	0.280 (0.598)
Medical history of chronic diseases
No	0.338 (0.562)	0.005 (0.942)	0.012 (0.913)	0.052 (0.820)	0.068 (0.795)
Yes
Smoking status
Never smoker	3.104 (0.049)	3.419 (0.036)	2.043 (0.135)	4.504 (0.013)	3.845 (0.024)
Ever smoker
Current smoker
Alcohol consumption
Never drinker	1.384 (0.255)	4.287 (0.016)	1.814 (0.168)	3.865 (0.024)	3.535 (0.033)
Ever drinker
Current drinker
COVID-19
No	1.894 (0.172)	4.049 (0.047)	3.139 (0.079)	4.826 (0.030)	3.217 (0.076)
Yes
Number of COVID-19 infections
0	0.762 (0.518)	1.962 (0.124)	2.926 (0.037)	2.466 (0.066)	2.405 (0.072)
1
2
3
SARS-CoV-2 vaccine dose
1	2.912 (0.038)	3.465 (0.019)	4.413 (0.006)	2.775 (0.045)	4.152 (0.008)
2
3
4
Inoculation status
Primary	6.542 (0.002)	1.863 (0.160)	3.336 (0.039)	4.503 (0.013)	5.529 (0.005)
Homologous booster
Heterologous booster
Time interval	4.812 (0.030)	1.741 (0.190)	7.640 (0.007)	4.552 (0.035)	3.772 (0.055)

The values in the table are F values after univariate analysis of the respective variables, and the values in parentheses are P values; p ≤ .05 (two-sided) is considered statistically significant.