Safety and immunogenicity of inactive vaccines as booster doses for COVID-19 in Türkiye: A randomized trial

Figures & data

Figure 1. Study flowchart.

†The median time elapsed after vaccination was 21 days (IQR, 13). Of four volunteers, three were males and one was female; the median age was 40.5 years (IQR, 17.25).

Table 1. Characteristics of the study participants.

	TURKOVAC (n = 108)	CoronaVac (n = 114)	p value
Age, years, Median (IQR)	39.0 (11)	38.5 (14)	.5133
Age, years, Mean (SD)	40 (8)	39 (9)	.5133
Volunteers by age groups, n (%)
18–44 years	71 (65.7)	80 (70.2)	.4789*
Female/Male	21 (29.6)/50 (70.4)	26 (32.5)/54 (67.5)
45–60 years	37 (34.3)	34 (29.8)
Female/Male	13 (35.1)/24(64.9)	12 (35.3)/22 (64.7)
18–29 years	13 (12.0)	20 (17.5)	.5873**
Female/Male	4 (30.8)/9 (69.2)	10 (50)/10 (50)
30–39 years	44 (40.7)	39 (34.2)
Female/Male	14 (31.8)/30 (68.2)	11 (28.2)/28 (71.8)
40–49 years	37 (34.3)	38 (33.3)
Female/Male	9 (24.3)/28 (75.7)	10 (26.3)/28 (73.7)
50–60 years	14 (13.0)	17 (14.9)
Female/Male	7 (50)/7 (50)	7 (41.2)/10 (58.8)
Volunteers by sex, n (%)
Female	34 (31.5)	38 (33.3)	.7682
Male	74 (68.5)	76 (66.7)
Body mass index, kg/m2, n (%)	26.9 (4.34)	26.0 (4.5)
<30	87 (82.9)	102 (89.5)	.1548
≥30	18 (17.1)	12 (10.5)
Smoking, No. (%)	52 (48.1)	56 (49.1)	.8845
Presence of comorbidities, No. (%)	26 (24.1)	28 (24.6)	.9325
Hypertension	6 (5.6)	8 (7.0)	-
Diabetes	2 (1.9)	3 (2.6)	-
Cardiovascular diseases***	1 (0.9)	1 (0.9)	-
Psoriasis	1 (0.9)	1 (0.9)	-
Asthma	1 (0.9)	(0)	-
Cancer	1 (0.9)	(0)	-
Other	14 (13.0)	15 (13.2)	-
The interval between the 2nd and 3rd doses (months), median (IQR)	4.9 (2.48)	4.5 (2.4)	.7348
Before 4 months, n (%)	47 (43.5)	50 (43.9)	.9591
4 months and after, n (%)	61 (56.5)	64 (56.1)
Before 6 months, n (%)	92 (85.2)	92 (80.7)	.3753
6 months and after, n (%)	16 (14.8)	22 (19.3)

*for comparison between 18–44 years and 45–60 years age groups; **for comparison between 18–29 years, 30–39 years, 40–49 years, and 50–60 years groups; †coronary heart disease, congestive heart failure and arrhythmia.

Figure 2. Neutralizing antibody positivity against the (a) Wuhan and (b) Delta variants, and (c) immunoglobulin G-Spike (IgG-S) positivity before and after booster doses in the two study arms.

Table 2. Change in spike-specific immunoglobulin G antibody levels before and after the booster doses.

	All volunteers		TURKOVAC		CoronaVac
Immunoglobulin G level, U/mL	N	Median (IQR)	N	Median (IQR)	N	Median (IQR)	p value
Before booster dose	222	1.30 (2.02)	108	1.30 (1.82)	114	1.30 (2.38)	.3397
After booster dose	217	16.90 (44.98)	103	26.69 (88.13)	114	12.38 (19.04)	.0002

IQR: interquantile range.

Table 3. Neutralizing antibody geometric mean titer results.

	All volunteers	TURKOVAC	CoronaVac
	GMT (95% CI)	GMT (95% CI)	GMT (95% CI)
Wuhan variant
Before booster dose	15.34 (12.82–18.36)	13.98 (10.77–18.13)	16.58 (13.12–20.95)
After booster dose	30.68 (26.76–35.18)	33.97 (27.77–41.54)	27.92 (23.37–33.35)
Delta variant
Before booster dose	12 (8.6–16.74)	12 (6.51–22.14)	12 (9.09–15.84)
After booster dose	12.3 (10.85–13.94)	14.36 (11.83–17.43)	10.49 (8.97–12.28)

GMT, geometric mean titer; CI, confidence interval.

Table 4. Frequency of adverse events in the two study arms.

	TURKOVAC	CoronaVac	p value
Adverse Events, n (%)	37 (34.3)	28 (24.6)	.1124
Local adverse events, n (%)	18 (16.7)	17 (14.9)	.8616
Pain at the injection site	12 (11.1)	10 (8.8)
Arm pain	6 (5.6)	4 (3.5)
Myalgia at the injection site	0 (0)	2 (1.8)
Induration	1 (0.9)	1 (0.9)
Pruritus at the injection site	0 (0)	1 (0.9)
Systemic adverse events, n (%)	25 (23.1)	18 (15.8)	.1655
Fatigue	7 (6.5)	8 (7.0)
Headache	5 (4.6)	3 (2.6)
COVID-19 positivity	7 (6.5)	4 (3.5)
Myalgia	3 (2.8)	4 (3.5)
Upper respiratory tract infection	3 (2.8)	6 (5.3)
Diarrhea	2 (1.9)	3 (2.6)
Pain	3 (2.8)	0 (0)
Sore throat	0 (0)	3 (2.6)
Chest pain	1 (0.9)	2 (1.8)
Fever	1 (0.9)	1 (0.9)
Nasal drainage	1 (0.9)	1 (0.9)
Asthenia	1 (0.9)	(0)
Pruritus	1 (0.9)	(0)
Rash	0 (0)	1 (0.9)
Tinnitus	1 (0.9)	0 (0)
Shortness of breath	1 (0.9)	0 (0)
Excessive breathing	0 (0)	1 (0.9)
Chills	0 (0)	1 (0.9)