Safety and immunogenicity of an indigenously developed tetanus toxoid, diphtheria toxoid, and acellular pertussis vaccine (Tdap) in adults, adolescents, and children in India

Figures & data

Figure 1. Participant flowchart.

Table 1. Demographics characteristics – ITT population (N = 1500).

Characteristics	Parameter/Categories	Cohort 1(≥ 18 to 65 years)		Cohort 2(10 to < 18 years)		Cohort 3(4 to < 10 years)		Overall
		SIIPL Tdap (N = 250)	Comparator (N = 250)	SIIPL Tdap (N = 251)	Comparator (N = 249)	SIIPL Tdap (N = 249)	Comparator (N = 251)	SIIPL Tdap (N = 750)	Comparator (N = 750)
Age in years (at vaccination)	Mean	33.6	33.9	12.6	13.0	6.3	6.2	17.5	17.7
	SD	9.96	9.54	2.14	2.20	1.93	1.85	13.12	13.16
	Median	32.0	32.0	12.0	13.0	6.0	5.0	12.0	13.0
	Range	(18:62)	(18:63)	(10:17)	(10:17)	(4:9)	(4:9)	(4:62)	(4:63)
Gender, n (%)	Male	110 (44.00%)	110 (44.00%)	134 (53.39%)	133 (53.41%)	137 (55.02%)	149 (59.36%)	381 (50.80%)	392 (52.27%)
	Female	140 (56.00%)	140 (56.00%)	117 (46.61%)	116 (46.59%)	112 (44.98%)	102 (40.64%)	369 (49.20%)	358 (47.73%)
Height (cm)	Mean	160.2	159.7	148.8	149.6	116.4	115.3	141.8	141.5
	SD	9.14	10.06	11.24	11.79	13.08	12.33	21.68	22.21
	Median	160.0	159.0	148.5	150.0	115.0	114.0	147.0	147.0
Weight (kg)	Mean	60.7	61.9	39.5	40.7	20.7	19.7	40.3	40.8
	SD	13.03	12.22	11.72	10.96	6.60	5.64	19.59	19.95
	Median	58.9	61.0	38.0	39.3	19.0	19.0	38.7	39.4

n: Subject Count, N: Sample Size.

Table 2. Summary of solicited adverse events after vaccination intention to treat population (N = 1500).

Adverse Event	SIIPL Tdap (N = 750)		Comparator Tdap (N = 750)		p-value^b
	n (%) [E]	95% CI^a	n (%) [E]	95% CI^a
Local adverse event
Injection site pain	308 (41.1%) [315]	[37.52:44.68]	322 (42.9%) [329]	[39.36:46.56]	0.464
Injection site erythema	17 (2.3%) [17]	[1.33:3.6]	8 (1.1%) [8]	[0.46:2.09]	0.069
Injection site swelling	46 (6.1%) [47]	[4.52:8.1]	42 (5.6%) [42]	[4.07:7.49]	0.660
Systemic adverse event
Fever	32 (4.3%) [38]	[2.94:5.97]	28 (3.7%) [36]	[2.49:5.35]	0.598
Dizziness	15 (2.0%) [16]	[1.12:3.28]	19 (2.5%) [20]	[1.53:3.93]	0.488
Fatigue	43 (5.7%) [44]	[4.18:7.65]	41 (5.5%) [42]	[3.95:7.34]	0.822
Headache	73 (9.7%) [76]	[7.71:12.08]	66 (8.8%) [70]	[6.87:11.06]	0.533
Malaise	21 (2.8%) [21]	[1.74:4.25]	18 (2.4%) [18]	[1.43:3.77]	0.626
Nausea	20 (2.7%) [23]	[1.64:4.09]	23 (3.1%) [25]	[1.95:4.57]	0.643

n (%), E: where n = number of participants with at least one adverse event (counted only once), % = (number of participants with at least one adverse event/number of participants in respective study vaccine group of safety population)*100 and E = number of adverse events, CI = confidence interval

a 95% CI were calculated by Clopper–Pearson Method.

b p-value was calculated using using Chi-square test. p-value below 0.05 was considered statistically significant.

Figure 2. Reverse cumulative distribution curves showing IgG antibody concentrations at Pre-vaccination (Pre) and 30 days after post-vaccination (Post) in per protocol population for anti- Diphtheria toxoid (DT) and anti-Tetanus Toxoid (TT). The X-axis is logarithmic. Y-axis is percentage of subjects. The units used in the multiplex immunoassay to measure IgG antibodies are International Units/ml (IU/ml).

Table 3. Seroprotection/Seropositivity in per protocol population (N = 1439) one month after vaccination with the SIIPL Tdap (N = 719) or Comparator Tdap (N = 720) vaccines.

Seroprotection/Seropositivity
Antibody	SIIPL Tdap			Comparator Tdap			Difference^b (%)	(95% CI)^c
	N	n	%^a	N	n	%		LL	UL
Anti-TT	719	719	100.00	720	719	99.86	0.14	−1.71	1.99
Anti-DT	719	675	93.88	720	678	94.17	−0.29	−2.68	2.11
Anti-PT	719	719	100.00	720	720	100.00	0.00	NE	NE
Anti-FHA	719	717	99.72	720	720	100.00	−0.28	−2.12	1.56
Anti-PRN	719	719	100.00	720	720	100.00	0.00	NE	NE

N = number of available participants for each of the antigen, n = number of participants achieving seroprotection/seropositivity, CI = confidence interval, LL = lower limit, UL = upper limit, NE = not estimable, TT = Tetanus Toxoid, DT = Diphtheria Toxoid, PT = Pertussis Toxiod, PRN = pertactin, FHA = filamentous hemagglutinin. N = number of subjects with pre- and post-vaccination results available

a Percentages were calculated using respective column header group count as denominator.

b Proportion in SIIPL Tdap group – Proportion in Comparator Tdap group

c Two-sided 95% CI for difference in proportion of subjects between groups were calculated using

Farrington-Manning Test

cutoff value for seroprotection against diphtheria and tetanus is ≥ 0.1 IU/ml. For pertussis, antigens cut off values for PT, FHA, and PRN, the values are 0.132 IU/ml, 0.468 IU/ml, and 0.772 IU/ml respectively.

Noninferiority was declared if the lower bound of the two-sided 95% CI for the treatment difference (SIIPL Tdap – Comparator Tdap) in proportions were greater than ≥ −10%.

Table 4. Booster responses in the per protocol population (N = 1439) one month after vaccination with the SIIPL Tdap (N = 719) or comparator Tdap (N = 720) vaccines.

Booster Response^a
Antibody	SIIPL Tdap			Comparator Tdap			Difference^c (%)	95% CI^d
	N	n	%^b	N	n	%^b		LL	UL
Anti-TT	719	541	75.2	720	524	72.8	2.47	−1.35	6.28
Anti-DT	719	509	70.8	720	551	76.5	−5.74	−9.54	−1.93
Anti-PT	719	678	94.3	720	659	91.5	2.77	0.20	5.34
Anti-FHA	719	683	95.0	720	686	95.3	−0.28	−2.57	2.00
Anti-PRN	719	666	92.6	720	662	91.9	0.68	−1.90	3.26

N = number of available participants for each of the antigen, n = number of participants achieving booster response, CI = confidence interval, LL = lower limit, UL = upper limit, TT = Tetanus Toxoid, DT = Diphtheria Toxoid, PT = Pertussis Toxiod, PRN = pertactin, FHA = filamentous hemagglutinin

a Booster responses were defined as below

For anti-D and anti-T:

• Initially, seronegative subjects (pre-vaccination concentration below cutoff: <0.1 IU/mL)

should have a concentration at least four times the cutoff, days after vaccination (post- vaccination concentration ≥ 0.4 IU/mL).

• Initially seropositive subjects (pre-vaccination concentration ≥0.1 IU/mL and <1 IU/mL)

Should have an increase of at least four times the pre-vaccination concentration, 30 days after vaccination.

• Initially seropositive subjects (pre-vaccination concentration ≥1 IU/mL) should have an

increase of at least two times the pre-vaccination concentration, 30 days after vaccination.

For pertussis antigens (PT, FHA, and PRN):

• For initially seronegative subjects with an increase in antibody concentrations of at least

four times the pre-vaccination concentration, 30 days after vaccination.

• For initially seropositive subjects, an increase in antibody concentrations of at least two times the

pre-vaccination concentration, 30 days after vaccination.

b Percentages were calculated as n/N x 100

C 95% CI difference in proportion of subjects between groups will be calculated using Farrington- Manning Test

d Proportion difference is the difference of booster response between groups.

Two-sided 95% CI for difference in proportion of subjects between groups were calculated using Farrington-Manning Test.

Noninferiority was declared if the lower bound of the two-sided 95% CI for the treatment difference (SIIPL Tdap – Comparator Tdap) in proportions will be greater than ≥ −10%.

Figure 3. Reverse cumulative distribution curves showing IgG antibodies concentration at Pre-vaccination (Pre)and 30-days post-vaccination (Post) IgG in per protocol population against PT (a), FHA (b), PRN (c) antigen. The X-axis is logarithmic. Y-axis is percentage of subjects. The units used in the multiplex immunoassay to measure IgG antibodies are International Units/ml (IU/ml).

Table 5. Non-inferiority assessment for anti-PT, anti-FHA, and anti-PRN GMCs one month after vaccination – per protocol population (N = 1439).

Pertussis antigen	SIIPL-Tdap (N = 719)		Comparator Tdap (N = 720)		Post-vaccination GMC ratio	95% CI^b
	Pre-vaccination GMC (IU/ml)	Post-vaccination GMC^a (IU/ml)	Pre-vaccination GMC^a (IU/ml)	Post-vaccination GMC (IU/ml)	SIIPL-Tdap /Comparator Tdap	LL	UL
Anti-PT	8.11	197.68	7.79	120.01	1.65	1.46	1.86
Anti-FHA	11.04	313.33	11.38	441.92	0.71	0.63	0.80
ANTI-PRN	5.72	172.23	4.76	156.69	1.1	0.95	1.28

Abbreviations: N = number of subjects with post-vaccination results available; GMC = Geometric Mean Concentration, PT = Pertussis Toxiod, PRN = pertactin, FHA = filamentous hemagglutinin, CI = confidence interval, LL = lower limit, UL = upper limit, IU = International Unit, ml = milliliter.

a GMC one month post-vaccination

b 95% CI were estimated from the ANCOVA

Non-inferiority was declared if the lower limit of the 95% CI of the GMC ratio (SIIPL Tdap/ Comparator Tdap) for each of the antigen was ≥ 0.67