Safety and immunogenicity of a third-dose homologous BBIBP-CorV boosting vaccination: interim results from a prospective open-label study

Figures & data

Figure 1. The flowchart of the study.

Table 1. Basic characteristics of participants.

	Booster group (n = 63)	Control group (n = 40)	P-value
Age (years)	28.0 (25.0–38.0)	25.0 (24.0–27.8)	0.002
Sex
Male (%)	27 (42.9%)	16 (40.0%)	0.774
Female (%)	36 (57.1%)	24 (60.0%)
Interval between the second and third doses
4–6 months (%)	29 (46.0%)	27 (67.5%)	0.033
7–8months (%)	34 (54.0%)	13 (32.5%)
BMI	22.2 (20.4-23.9)	23.2 (20.7-25.4)	0.400
Ethnic group, Asian	63 (100.0%)	40 (100.0%)	–
Age groups
<40 years	50/63 (79.4%)	32/40 (80.0%)	0.938
Male (%)	21/50 (42.0%)	13/32 (40.6%)	0.902
Female (%)	29/50 (58.0%)	19/32 (59.4%)
An interval of 4–6 months between the second and third doses	26/50 (52.0%)	26/32 (81.3%)	0.007
An interval of 7–8 months between the second and third doses	24/50 (48.0%)	6/32 (18.8%)
BMI	22.0 (20.4–23.8)	22.4 (20.2–25.3)	0.497
≥40 years	13/63 (20.6%)	8/40 (20.0%)	0.938
Male (%)	6/13 (46.2%)	3/8 (37.5%)	0.999
Female (%)	7/13 (53.8%)	5/8 (62.5%)
An interval of 4–6 months between the second and third doses	3/13 (23.1%)	1/8 (12.5%)	0.502
An interval of 7–8 months between the second and third doses	10/13 (76.9%)	7/8 (87.5%)
BMI	22.9 (21.3–24.0)	24.7 (23.5–27.9)	0.080

Note: Date presented as Median (interquartile) or number (percentage).

For all categorical variables, the Chi-Square statistic was used.

Continuous variables were compared using a Mann–Whitney test.

P < 0.05 was considered statistically significant for all analyses. BMI = Body Mass Index.

Figure 2. Immune response after the third-dose vaccination. (a) IFN-γ SFU/million PBMCs after the third-dose vaccination. (b) Humoral immune responses against prototype and variants of SARS-CoV-2 after the third-dose vaccination evaluated by pVNT. (c) Humoral immune responses after the third-dose vaccination evaluated by sVNT. (d) Humoral immune responses after the third-dose vaccination evaluated by an anti-RBD antibody. (e) Humoral immune responses after the third-dose vaccination evaluated by anti-RBD IgG.

Figure 3. Impact of the interval among three doses of BBIBP-CorV vaccinations on humoral immune responses and T-cell response. (a) pVNT titer against prototype and variants of SARS-CoV-2 in participants administered with third doses at 4–6 months and 7–8 months intervals after second doses; (b) T-cell response in participants administered with third doses at 4–6 months and 7–8 months intervals after second doses.

Table 2. Solicited and unsolicited adverse reactions.

	Total*	Day0-Day3	Day4-Day14	Day15-Day28
Solicited adverse reactions
Injection site adverse reactions
Any (%)	28 (44.4%)	26 (41.3%)	7 (11.1%)	3 (4.8%)
Grade 1	28 (44.4%)	26 (41.3%)	7 (11.1%)	3 (4.8%)
Pain	28 (44.4%)	26 (41.3%)	6 (9.5%)	3 (4.8%)
Grade 1	28 (44.4%)	26 (41.3%)	6 (9.5%)	3 (4.8%)
Induration	1 (1.6%)	1 (1.6%)	0 (0.0%)	0 (0.0%)
Grade 1	1 (1.6%)	1 (1.6%)	0 (0.0%)	0 (0.0%)
Swelling	3 (4.8%)	2 (3.2%)	1 (1.6%)	0 (0.0%)
Grade 1	3 (4.8%)	2 (3.2%)	1 (1.6%)	0 (0.0%)
Erythema	0 (0.0%)	0 (0.0%)	0 (0.0%)	0 (0.0%)
Pruritus	0 (0.0%)	0 (0.0%)	0 (0.0%)	0 (0.0%)
Systematic adverse reactions
Any (%)	14 (22.2%)	11 (17.5%)	2 (3.2%)	1 (1.6%)
Grade 1	14 (22.2%)	11 (17.5%)	2 (3.2%)	1 (1.6%)
Fever	3 (4.8%)	2 (3.2%)	2 (3.2%)	0 (0.0%)
Grade 1	3 (4.8%)	2 (3.2%)	2 (3.2%)	0 (0.0%)
Fatigue	5 (7.9%)	4 (6.3%)	0 (0.0%)	1 (1.6%)
Grade 1	5 (7.9%)	4 (6.3%)	0 (0.0%)	1 (1.6%)
Myalgia	2 (3.2%)	2 (3.2%)	0 (0.0%)	0 (0.0%)
Grade 1	2 (3.2%)	2 (3.2%)	0 (0.0%)	0 (0.0%)
Vertigo	3 (4.8%)	3 (4.8%)	0 (0.0%)	0 (0.0%)
Grade 1	3 (4.8%)	3 (4.8%)	0 (0.0%)	0 (0.0%)
Anorexia	1 (1.6%)	0 (0.0%)	0 (0.0%)	1 (1.6%)
Grade 1	1 (1.6%)	0 (0.0%)	0 (0.0%)	1 (1.6%)
Rash	0 (0.0%)	0 (0.0%)	0 (0.0%)	0 (0.0%)
Cough	0 (0.0%)	0 (0.0%)	0 (0.0%)	0 (0.0%)
Arthralgia	0 (0.0%)	0 (0.0%)	0 (0.0%)	0 (0.0%)
Dyspnoea	0 (0.0%)	0 (0.0%)	0 (0.0%)	0 (0.0%)
Nausea	0 (0.0%)	0 (0.0%)	0 (0.0%)	0 (0.0%)
Pharyngalgia	0 (0.0%)	0 (0.0%)	0 (0.0%)	0 (0.0%)
Syncope	0 (0.0%)	0 (0.0%)	0 (0.0%)	0 (0.0%)
Vomiting	0 (0.0%)	0 (0.0%)	0 (0.0%)	0 (0.0%)
Unsolicited adverse reactions
Injection site adverse reactions
Any (%)	0 (0.0%)	0 (0.0%)	0 (0.0%)	0 (0.0%)
Systematic adverse reactions
Any (%)	6 (9.5%)	5 (7.9%)	1 (1.6%)	0 (0.0%)
Grade 1	6 (9.5%)	5 (7.9%)	1 (1.6%)	0 (0.0%)
Diarrhoea	3 (4.8%)	3 (4.8%)	0 (0.0%)	0 (0.0%)
Grade 1	3 (4.8%)	3 (4.8%)	0 (0.0%)	0 (0.0%)
Flatus	1 (1.6%)	1 (1.6%)	0 (0.0%)	0 (0.0%)
Grade 1	1 (1.6%)	1 (1.6%)	0 (0.0%)	0 (0.0%)
Rhinorrhoea	1 (1.6%)	1 (1.6%)	0 (0.0%)	0 (0.0%)
Grade 1	1 (1.6%)	1 (1.6%)	0 (0.0%)	0 (0.0%)
Lethargy	1 (1.6%)	0 (0.0%)	1 (1.6%)	0 (0.0%)
Grade 1	1 (1.6%)	0 (0.0%)	1 (1.6%)	0 (0.0%)

Note: *Total number of participants who had adverse events throughout the 28-day observation. If a participant had a persistent or recurrent symptom, it would be counted only once.