Persistence of immunogenicity, contributing factors of an immune response, and reactogenicities after a single dose of the ChAdOx1 (AZD1222) COVID-19 vaccine in the Thai population

Figures & data

Table 1. Demographic characteristics of study participants

	All participants (N = 794)
Female, n (%)	517 (65.1%)
Age (years), median (IQR)	40 (30, 57)
Underlying comorbidities
Cardiovascular disease	5 (0.63%)
Diabetes	11 (1.39%)
Obese	1 (0.13%)
Hypertension	26 (3.27%)
Dyslipidemia	27 (3.40%)
Hematologic disease	8 (1.00%)

IQR, interquartile range. Obese; body mass index > 25 kg/m^2.

Table 2. The geometric mean concentration (GMC) of anti-RBD antibody after a single dose of the AZD1222 vaccine (weeks)

Time elapsed from first dose of AZD1222 (weeks)	Sample (N)	Geometric mean concentration of anti-SARS-CoV-2 antibody concentration (95%CI) (BAU/mL)	Geometric mean ratio (95%CI)*
Baseline level	794	< 0.4
3	118	14.80 (10.81, 20.23)	Reference
4	120	27.23 (20.84,35.56)	1.79 (1.30, 2.48)
5	123	46.56 (37.07,58.34)	3.05 (2.22, 4.18)
6	251	48.87 (41.50, 57.54)	3.79 (2.86, 5.01)
7	63	47.97 (37.41, 61.52)	4.78 (3.21, 7.11)
8	1	65.48	4.28 (0.36, 50.58)
9	66	56.75 (42.46, 75.86)	4.20 (2.88, 6.12)
10	382	65.16 (58.48, 72.44)	4.47 (3.43, 5.81)
11	31	83.75 (55.98, 125.31)	5.58 (3.41, 9.16)

*adjust with age, sex, underlying disease, GMR; geometric mean ratio, 95%CI; 95% confidence interval.

Table 3. The geometric mean concentration (GMC) of anti-RBD antibody after a single dose of the AZD1222 vaccine (months)

Time elapsed from the first dose of AZD1222 (month)	Sample (N)	GMC of anti-SARS-CoV-2 antibody (95%CI) (BAU/mL)	GMR (95%CI)*
Baseline level	794	0.4
1	238	20.14 (16.37, 24.77)	reference
2	438	48.08 (42.76, 54.08)	2.72 (2.21–3.33)
3	479	65.01 (58.88,71.61)	3.33 (2.73–4.05)

*adjust with age, sex, underlying disease, GMR; geometric mean ratio, 95%CI; 95% confidence interval.

Table 4. Linear regression analysis of contributing factors of anti-RBD antibody concentration (antilogarithm)

Predictor	Adjusted^a (95%CI)
R^2	0.132
Sex
Female	reference
Male	0.71 (0.61–0.84)
Age (decades)	0.85 (0.80–0.90)
Time elapsed from first dose of AZD1222 (weeks)	1.16 (1.13–1.20)
Underlying comorbidity
Cardiovascular disease	0.11 (0.39–1.65)
Diabetes	0.45 (0.26–0.77)*
Obese	0.48 (0.04–5.79)
Hypertension	0.90 (0.58–1.39)
Dyslipidemia	0.64 (0.40–1.04)
End-stage kidney disease	0.20 (0.02–2.32)
Hematologic disease	0.44 (0.20–0.97)*

^aadjust with age, sex, underlying comorbidity, and time elapsed after the first dose. 95%CI; 95% confidence interval. * p-value <.05.

Figure 1. Anti-RBD antibody levels over 11 weeks following the first dose of the AZD1222 vaccine.

Figure 2. Anti-RBD antibody levels over 3 months following the first dose of the AZD1222 vaccine.

Figure 3. Reactogenicities after a first dose of AZD1222 vaccine within 7 days.