Trial Outcomes & Findings for Long-term Persistence of Hepatitis B and Pertussis Antibody Responses in Healthy 4 to 5 Year Old Children Previously Vaccinated With Vaxelis® or INFANRIX® Hexa (V419-012) (NCT NCT02759354)

Results Overview

Participant serum samples were collected for testing with an enhanced chemiluminescence assay for antibodies to HBsAg. Response was defined as a titer \>=10 milli International units (mIU)/mL. Confidence Intervals were calculated based on the exact binomial method of D. Collett.

Recruitment status

COMPLETED

Study phase

PHASE3

Target enrollment

754 participants

Primary outcome timeframe

Day 1 (approximately 4 years after completion of the 3+1/2+1 schedule)

Results posted on

2020-06-09

Participant Flow

This multicenter extension study was conducted in Finland at approximately 10 sites from studies V419-007 and V419-008, which had eligible participants(i.e. participants who completed the full 3+1 or 2+1 vaccination schedule in the original studies).

Of the 760 screened participants, 754 were enrolled and completed the study. A total of 752 participants were included in the Persistence Analysis Set, 752 with blood samples available for hepatitis B surface antigen (HBsAg) analyses, and 751 for pertussis analyses.

Participant milestones

Participant milestones
Measure	Group Vaxelis (3+1) Participants previously vaccinated with a 3-dose primary series of Vaxelis® at 2, 3 and 4 months of age, and a toddler dose at 12 months of age (study V419-007). On Day 1 of this extension study (\~4 years after completion of the 3+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.	Group Infanrix Hexa (3+1) Participants previously vaccinated with a 3-dose primary series of INFANRIX® hexa at 2, 3 and 4 months of age, and a toddler dose at 12 months of age (study V419-007). On Day 1 of this extension study (\~4 years after completion of the 3+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.	Group Vaxelis (2+1) Participants previously vaccinated with a 2-dose primary series of Vaxelis® at 2 and 4 months of age, and a toddler dose at 11-12 months of age (study V419-008). On Day 1 of this extension study (\~4 years after completion of the 2+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.	Group Infanrix Hexa (2+1) Participants previously vaccinated with a 2-dose primary series of INFANRIX® hexa at 2 and 4 months of age, and a toddler dose at 11-12 months of age (study V419-008). On Day 1 of this extension study (\~4 years after completion of the 2+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.
Overall Study STARTED	192	190	181	191
Overall Study COMPLETED	192	190	181	191
Overall Study NOT COMPLETED	0	0	0	0

Reasons for withdrawal

Withdrawal data not reported

Baseline Characteristics

Long-term Persistence of Hepatitis B and Pertussis Antibody Responses in Healthy 4 to 5 Year Old Children Previously Vaccinated With Vaxelis® or INFANRIX® Hexa (V419-012)

Baseline characteristics by cohort

Baseline characteristics by cohort
Measure	Group Vaxelis (3+1) n=191 Participants Participants previously vaccinated with a 3-dose primary series of Vaxelis® at 2, 3 and 4 months of age, and a toddler dose at 12 months of age (study V419-007). On Day 1 of this extension study (\~4 years after completion of the 3+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.	Group Infanrix Hexa (3+1) n=189 Participants Participants previously vaccinated with a 3-dose primary series of INFANRIX® hexa at 2, 3 and 4 months of age, and a toddler dose at 12 months of age (study V419-007). On Day 1 of this extension study (\~4 years after completion of the 3+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.	Group Vaxelis (2+1) n=181 Participants Participants previously vaccinated with a 2-dose primary series of Vaxelis® at 2 and 4 months of age, and a toddler dose at 11-12 months of age (study V419-008). On Day 1 of this extension study (\~4 years after completion of the 2+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.	Group Infanrix Hexa (2+1) n=191 Participants Participants previously vaccinated with a 2-dose primary series of INFANRIX® hexa at 2 and 4 months of age, and a toddler dose at 11-12 months of age (study V419-008). On Day 1 of this extension study (\~4 years after completion of the 2+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.	Total n=752 Participants Total of all reporting groups
Age, Continuous	4.8 Years STANDARD_DEVIATION 0.2 • n=5 Participants	4.8 Years STANDARD_DEVIATION 0.2 • n=7 Participants	3.9 Years STANDARD_DEVIATION 0.1 • n=5 Participants	3.9 Years STANDARD_DEVIATION 0.1 • n=4 Participants	4.4 Years STANDARD_DEVIATION 0.4 • n=21 Participants
Sex: Female, Male Female	98 Participants n=5 Participants	86 Participants n=7 Participants	84 Participants n=5 Participants	94 Participants n=4 Participants	362 Participants n=21 Participants
Sex: Female, Male Male	93 Participants n=5 Participants	103 Participants n=7 Participants	97 Participants n=5 Participants	97 Participants n=4 Participants	390 Participants n=21 Participants

PRIMARY outcome

Timeframe: Day 1 (approximately 4 years after completion of the 3+1/2+1 schedule)

Population: All analyses were performed on the Persistence Analysis Set, defined as all participants previously vaccinated (with a complete 3+1 or 2+1 schedule, as part of studies V419-007 or V419-008) with available immunogenicity data for the respective endpoint.

Participant serum samples were collected for testing with an enhanced chemiluminescence assay for antibodies to HBsAg. Response was defined as a titer \>=10 milli International units (mIU)/mL. Confidence Intervals were calculated based on the exact binomial method of D. Collett.

Outcome measures

Outcome measures
Measure	Group Vaxelis (3+1) n=191 Participants Participants previously vaccinated with a 3-dose primary series of Vaxelis® at 2, 3 and 4 months of age, and a toddler dose at 12 months of age (study V419-007). On Day 1 of this extension study (\~4 years after completion of the 3+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.	Group Infanrix Hexa (3+1) n=189 Participants Participants previously vaccinated with a 3-dose primary series of INFANRIX® hexa at 2, 3 and 4 months of age, and a toddler dose at 12 months of age (study V419-007). On Day 1 of this extension study (\~4 years after completion of the 3+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.	Group Vaxelis (2+1) n=181 Participants Participants previously vaccinated with a 2-dose primary series of Vaxelis® at 2 and 4 months of age, and a toddler dose at 11-12 months of age (study V419-008). On Day 1 of this extension study (\~4 years after completion of the 2+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.	Group Infanrix Hexa (2+1) n=190 Participants Participants previously vaccinated with a 2-dose primary series of INFANRIX® hexa at 2 and 4 months of age, and a toddler dose at 11-12 months of age (study V419-008). On Day 1 of this extension study (\~4 years after completion of the 2+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.
Percentage of Participants Responding to Hepatitis B Surface Antigen (HBsAg)	70.16 Percentage of Participants Interval 63.13 to 76.55	82.01 Percentage of Participants Interval 75.78 to 87.21	65.75 Percentage of Participants Interval 58.34 to 72.63	83.68 Percentage of Participants Interval 77.65 to 88.64

PRIMARY outcome

Timeframe: Day 1 (approximately 4 years after completion of the 2+1 schedule)

Population: The analysis population was the Persistence Analysis Set, all participants previously vaccinated with complete 2+1 schedule (V419-008) with available immunogenicity data for the respective endpoint. Due to pre-school enrollment and booster administration, assessment of pertussis antibody persistence was not possible for the 3+1 schedule (V419-007).

Participant serum samples were collected for testing with an Enzyme-linked Immunosorbent Assay (ELISA) for antibodies to pertussis toxin. The unit of measure is ELISA units/mL. The lower limit of quantification (LLOQ)=4 EU/mL. Confidence Intervals were calculated based on the exact binomial method of D. Collett.

Outcome measures

Outcome measures
Measure	Group Vaxelis (3+1) n=178 Participants Participants previously vaccinated with a 3-dose primary series of Vaxelis® at 2, 3 and 4 months of age, and a toddler dose at 12 months of age (study V419-007). On Day 1 of this extension study (\~4 years after completion of the 3+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.	Group Infanrix Hexa (3+1) n=188 Participants Participants previously vaccinated with a 3-dose primary series of INFANRIX® hexa at 2, 3 and 4 months of age, and a toddler dose at 12 months of age (study V419-007). On Day 1 of this extension study (\~4 years after completion of the 3+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.	Group Vaxelis (2+1) Participants previously vaccinated with a 2-dose primary series of Vaxelis® at 2 and 4 months of age, and a toddler dose at 11-12 months of age (study V419-008). On Day 1 of this extension study (\~4 years after completion of the 2+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.	Group Infanrix Hexa (2+1) Participants previously vaccinated with a 2-dose primary series of INFANRIX® hexa at 2 and 4 months of age, and a toddler dose at 11-12 months of age (study V419-008). On Day 1 of this extension study (\~4 years after completion of the 2+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.
Percentage of Participants Responding to Pertussis Toxin Concentration ≥LLOQ	58.43 Percentage of participants Interval 50.82 to 65.75	41.49 Percentage of participants Interval 34.37 to 48.89	—	—
Percentage of Participants Responding to Pertussis Toxin Concentration ≥2×LLOQ	40.45 Percentage of participants Interval 33.17 to 48.05	21.81 Percentage of participants Interval 16.13 to 28.4	—	—
Percentage of Participants Responding to Pertussis Toxin Concentration ≥4×LLOQ	14.61 Percentage of participants Interval 9.77 to 20.67	3.72 Percentage of participants Interval 1.51 to 7.52	—	—

PRIMARY outcome

Timeframe: Day 1 (approximately 4 years after completion of the 2+1 schedule)

Population: The analysis population was the Persistence Analysis Set, all participants previously vaccinated with complete 2+1 schedule (V419-008) with available immunogenicity data for the respective endpoint. Due to pre-school enrollment and booster administration, assessment of pertussis antibody persistence was not possible for the 3+1 schedule (V419-007).

Participant serum samples were collected for testing with an ELISA for antibodies to pertussis filamentous hemagglutinin. LLOQ=3 EU/mL. Confidence Intervals were calculated based on the exact binomial method of D. Collett.

Outcome measures

Outcome measures
Measure	Group Vaxelis (3+1) n=173 Participants Participants previously vaccinated with a 3-dose primary series of Vaxelis® at 2, 3 and 4 months of age, and a toddler dose at 12 months of age (study V419-007). On Day 1 of this extension study (\~4 years after completion of the 3+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.	Group Infanrix Hexa (3+1) n=188 Participants Participants previously vaccinated with a 3-dose primary series of INFANRIX® hexa at 2, 3 and 4 months of age, and a toddler dose at 12 months of age (study V419-007). On Day 1 of this extension study (\~4 years after completion of the 3+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.	Group Vaxelis (2+1) Participants previously vaccinated with a 2-dose primary series of Vaxelis® at 2 and 4 months of age, and a toddler dose at 11-12 months of age (study V419-008). On Day 1 of this extension study (\~4 years after completion of the 2+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.	Group Infanrix Hexa (2+1) Participants previously vaccinated with a 2-dose primary series of INFANRIX® hexa at 2 and 4 months of age, and a toddler dose at 11-12 months of age (study V419-008). On Day 1 of this extension study (\~4 years after completion of the 2+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.
Percentage of Participants Responding to Pertussis Filamentous Hemagglutinin Concentration ≥LLOQ	80.92 Percentage of participants Interval 74.27 to 86.49	88.30 Percentage of participants Interval 82.82 to 92.52	—	—
Percentage of Participants Responding to Pertussis Filamentous Hemagglutinin Concentration ≥2×LLOQ	46.82 Percentage of participants Interval 39.21 to 54.54	70.74 Percentage of participants Interval 63.68 to 77.14	—	—
Percentage of Participants Responding to Pertussis Filamentous Hemagglutinin Concentration ≥4×LLOQ	26.01 Percentage of participants Interval 19.65 to 33.22	45.21 Percentage of participants Interval 37.96 to 52.62	—	—

PRIMARY outcome

Timeframe: Day 1 (approximately 4 years after completion of the 2+1 schedule)

Population: The analysis population was the Persistence Analysis Set, all participants previously vaccinated with complete 2+1 schedule (V419-008) with available immunogenicity data for the respective endpoint. Due to pre-school enrollment and booster administration, assessment of pertussis antibody persistence was not possible for the 3+1 schedule (V419-007).

Participant serum samples were collected for testing with an ELISA for antibodies to pertussis pertactin. LLOQ=4 EU/mL. Confidence Intervals were calculated based on the exact binomial method of D. Collett.

Outcome measures

Outcome measures
Measure	Group Vaxelis (3+1) n=180 Participants Participants previously vaccinated with a 3-dose primary series of Vaxelis® at 2, 3 and 4 months of age, and a toddler dose at 12 months of age (study V419-007). On Day 1 of this extension study (\~4 years after completion of the 3+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.	Group Infanrix Hexa (3+1) n=190 Participants Participants previously vaccinated with a 3-dose primary series of INFANRIX® hexa at 2, 3 and 4 months of age, and a toddler dose at 12 months of age (study V419-007). On Day 1 of this extension study (\~4 years after completion of the 3+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.	Group Vaxelis (2+1) Participants previously vaccinated with a 2-dose primary series of Vaxelis® at 2 and 4 months of age, and a toddler dose at 11-12 months of age (study V419-008). On Day 1 of this extension study (\~4 years after completion of the 2+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.	Group Infanrix Hexa (2+1) Participants previously vaccinated with a 2-dose primary series of INFANRIX® hexa at 2 and 4 months of age, and a toddler dose at 11-12 months of age (study V419-008). On Day 1 of this extension study (\~4 years after completion of the 2+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.
Percentage of Participants Responding to Pertussis Pertactin Concentration ≥LLOQ	66.11 Percentage of participants Interval 58.7 to 72.99	72.63 Percentage of participants Interval 65.71 to 78.84	—	—
Percentage of Participants Responding to Pertussis Pertactin Concentration ≥2×LLOQ	43.89 Percentage of participants Interval 36.52 to 51.47	51.05 Percentage of participants Interval 43.71 to 58.36	—	—
Percentage of Participants Responding to Pertussis Pertactin Concentration ≥4×LLOQ	15.56 Percentage of participants Interval 10.59 to 21.69	18.42 Percentage of participants Interval 13.18 to 24.68	—	—

PRIMARY outcome

Timeframe: Day 1 (approximately 4 years after completion of the 2+1 schedule)

Population: The analysis population was the Persistence Analysis Set, all participants previously vaccinated with complete 2+1 schedule (V419-008) with available immunogenicity data for the respective endpoint. Due to pre-school enrollment and booster administration, assessment of pertussis antibody persistence was not possible for the 3+1 schedule (V419-007).

Participant serum samples were collected for testing with an ELISA for antibodies to pertussis fimbriae. LLOQ=4 EU/mL. Confidence Intervals were calculated based on the exact binomial method of D. Collett.

Outcome measures

Outcome measures
Measure	Group Vaxelis (3+1) n=177 Participants Participants previously vaccinated with a 3-dose primary series of Vaxelis® at 2, 3 and 4 months of age, and a toddler dose at 12 months of age (study V419-007). On Day 1 of this extension study (\~4 years after completion of the 3+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.	Group Infanrix Hexa (3+1) n=183 Participants Participants previously vaccinated with a 3-dose primary series of INFANRIX® hexa at 2, 3 and 4 months of age, and a toddler dose at 12 months of age (study V419-007). On Day 1 of this extension study (\~4 years after completion of the 3+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.	Group Vaxelis (2+1) Participants previously vaccinated with a 2-dose primary series of Vaxelis® at 2 and 4 months of age, and a toddler dose at 11-12 months of age (study V419-008). On Day 1 of this extension study (\~4 years after completion of the 2+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.	Group Infanrix Hexa (2+1) Participants previously vaccinated with a 2-dose primary series of INFANRIX® hexa at 2 and 4 months of age, and a toddler dose at 11-12 months of age (study V419-008). On Day 1 of this extension study (\~4 years after completion of the 2+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.
Percentage of Participants Responding to Pertussis Fimbriae Concentration ≥LLOQ	94.35 Percentage of participants Interval 89.86 to 97.26	3.28 Percentage of participants Interval 1.21 to 7.0	—	—
Percentage of Participants Responding to Pertussis Fimbriae Concentration ≥2×LLOQ	88.14 Percentage of participants Interval 82.44 to 92.5	2.19 Percentage of participants Interval 0.6 to 5.5	—	—
Percentage of Participants Responding to Pertussis Fimbriae Concentration ≥4×LLOQ	69.49 Percentage of participants Interval 62.14 to 76.18	1.09 Percentage of participants Interval 0.13 to 3.89	—	—

SECONDARY outcome

Timeframe: Day 1 (approximately 4 years after completion of the 3+1 or 2+1 schedule)

Population: All analyses were performed on the Persistence Analysis Set, defined as all participants previously vaccinated (with a complete 3+1 or 2+1 schedule, as part of studies V419-007 or V419-008) with available immunogenicity data for the respective endpoint.

Participant serum samples were collected for testing with an enhanced chemiluminescence assay for antibodies to HBsAg. The unit of measure is milli International Units/mL (mIU/mL). Confidence Intervals were calculated based on the t-distribution of the log-transformed antibody concentration.

Outcome measures

Outcome measures
Measure	Group Vaxelis (3+1) n=191 Participants Participants previously vaccinated with a 3-dose primary series of Vaxelis® at 2, 3 and 4 months of age, and a toddler dose at 12 months of age (study V419-007). On Day 1 of this extension study (\~4 years after completion of the 3+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.	Group Infanrix Hexa (3+1) n=189 Participants Participants previously vaccinated with a 3-dose primary series of INFANRIX® hexa at 2, 3 and 4 months of age, and a toddler dose at 12 months of age (study V419-007). On Day 1 of this extension study (\~4 years after completion of the 3+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.	Group Vaxelis (2+1) n=181 Participants Participants previously vaccinated with a 2-dose primary series of Vaxelis® at 2 and 4 months of age, and a toddler dose at 11-12 months of age (study V419-008). On Day 1 of this extension study (\~4 years after completion of the 2+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.	Group Infanrix Hexa (2+1) n=190 Participants Participants previously vaccinated with a 2-dose primary series of INFANRIX® hexa at 2 and 4 months of age, and a toddler dose at 11-12 months of age (study V419-008). On Day 1 of this extension study (\~4 years after completion of the 2+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.
Geometric Mean Concentration of Antibodies to HBsAg	24.43 mIU/mL Interval 19.52 to 30.59	51.30 mIU/mL Interval 40.19 to 65.46	19.44 mIU/mL Interval 15.48 to 24.4	71.00 mIU/mL Interval 54.94 to 91.77

SECONDARY outcome

Timeframe: Day 1 (approximately 4 years after completion of the 2+1 schedule)

Population: The analysis population was the Persistence Analysis Set, all participants previously vaccinated with complete 2+1 schedule (V419-008) with available immunogenicity data for the respective endpoint. Due to pre-school enrollment and booster administration, assessment of pertussis antibody persistence was not possible for the 3+1 schedule (V419-007).

Participant serum samples were collected for testing with an ELISA for antibodies to pertussis toxin. The unit of measure is ELISA units/mL (EU/mL). Confidence Intervals were calculated based on the t-distribution of the log-transformed antibody concentration.

Outcome measures

Outcome measures
Measure	Group Vaxelis (3+1) n=178 Participants Participants previously vaccinated with a 3-dose primary series of Vaxelis® at 2, 3 and 4 months of age, and a toddler dose at 12 months of age (study V419-007). On Day 1 of this extension study (\~4 years after completion of the 3+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.	Group Infanrix Hexa (3+1) n=188 Participants Participants previously vaccinated with a 3-dose primary series of INFANRIX® hexa at 2, 3 and 4 months of age, and a toddler dose at 12 months of age (study V419-007). On Day 1 of this extension study (\~4 years after completion of the 3+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.	Group Vaxelis (2+1) Participants previously vaccinated with a 2-dose primary series of Vaxelis® at 2 and 4 months of age, and a toddler dose at 11-12 months of age (study V419-008). On Day 1 of this extension study (\~4 years after completion of the 2+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.	Group Infanrix Hexa (2+1) Participants previously vaccinated with a 2-dose primary series of INFANRIX® hexa at 2 and 4 months of age, and a toddler dose at 11-12 months of age (study V419-008). On Day 1 of this extension study (\~4 years after completion of the 2+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.
Geometric Mean Concentration of Antibodies to Pertussis Toxin	5.31 EU/mL Interval 4.61 to 6.12	3.64 EU/mL Interval 3.24 to 4.09	—	—

SECONDARY outcome

Timeframe: Day 1 (approximately 4 years after completion of the 2+1 schedule)

Population: The analysis population was the Persistence Analysis Set, all participants previously vaccinated with complete 2+1 schedule (V419-008) with available immunogenicity data for the respective endpoint. Due to pre-school enrollment and booster administration, assessment of pertussis antibody persistence was not possible for the 3+1 schedule (V419-007).

Participant serum samples were collected for testing with an ELISA for antibodies to pertussis filamentous hemagglutinin. Confidence Intervals were calculated based on the t-distribution of the log-transformed antibody concentration.

Outcome measures

Outcome measures
Measure	Group Vaxelis (3+1) n=173 Participants Participants previously vaccinated with a 3-dose primary series of Vaxelis® at 2, 3 and 4 months of age, and a toddler dose at 12 months of age (study V419-007). On Day 1 of this extension study (\~4 years after completion of the 3+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.	Group Infanrix Hexa (3+1) n=188 Participants Participants previously vaccinated with a 3-dose primary series of INFANRIX® hexa at 2, 3 and 4 months of age, and a toddler dose at 12 months of age (study V419-007). On Day 1 of this extension study (\~4 years after completion of the 3+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.	Group Vaxelis (2+1) Participants previously vaccinated with a 2-dose primary series of Vaxelis® at 2 and 4 months of age, and a toddler dose at 11-12 months of age (study V419-008). On Day 1 of this extension study (\~4 years after completion of the 2+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.	Group Infanrix Hexa (2+1) Participants previously vaccinated with a 2-dose primary series of INFANRIX® hexa at 2 and 4 months of age, and a toddler dose at 11-12 months of age (study V419-008). On Day 1 of this extension study (\~4 years after completion of the 2+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.
Geometric Mean Concentration of Antibodies to Pertussis Filamentous Hemagglutinin	6.62 EU/mL Interval 5.54 to 7.91	11.05 EU/mL Interval 9.13 to 13.37	—	—

SECONDARY outcome

Timeframe: Day 1 (approximately 4 years after completion of the 2+1 schedule)

Population: The analysis population was the Persistence Analysis Set, all participants previously vaccinated with complete 2+1 schedule (V419-008) with available immunogenicity data for the respective endpoint. Due to pre-school enrollment and booster administration, assessment of pertussis antibody persistence was not possible for the 3+1 schedule (V419-007).

Participant serum samples were collected for testing with an ELISA for antibodies to pertussis pertactin. Confidence Intervals were calculated based on the t-distribution of the log-transformed antibody concentration.

Outcome measures

Outcome measures
Measure	Group Vaxelis (3+1) n=180 Participants Participants previously vaccinated with a 3-dose primary series of Vaxelis® at 2, 3 and 4 months of age, and a toddler dose at 12 months of age (study V419-007). On Day 1 of this extension study (\~4 years after completion of the 3+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.	Group Infanrix Hexa (3+1) n=190 Participants Participants previously vaccinated with a 3-dose primary series of INFANRIX® hexa at 2, 3 and 4 months of age, and a toddler dose at 12 months of age (study V419-007). On Day 1 of this extension study (\~4 years after completion of the 3+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.	Group Vaxelis (2+1) Participants previously vaccinated with a 2-dose primary series of Vaxelis® at 2 and 4 months of age, and a toddler dose at 11-12 months of age (study V419-008). On Day 1 of this extension study (\~4 years after completion of the 2+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.	Group Infanrix Hexa (2+1) Participants previously vaccinated with a 2-dose primary series of INFANRIX® hexa at 2 and 4 months of age, and a toddler dose at 11-12 months of age (study V419-008). On Day 1 of this extension study (\~4 years after completion of the 2+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.
Geometric Mean Concentration of Antibodies to Pertussis Pertactin	5.94 EU/mL Interval 5.14 to 6.86	7.19 EU/mL Interval 6.2 to 8.33	—	—

SECONDARY outcome

Timeframe: Day 1 (approximately 4 years after completion of the 2+1 schedule)

Population: The analysis population was the Persistence Analysis Set, all participants previously vaccinated with complete 2+1 schedule (V419-008) with available immunogenicity data for the respective endpoint. Due to pre-school enrollment and booster administration, assessment of pertussis antibody persistence was not possible for the 3+1 schedule (V419-007).

Participant serum samples were collected for testing with an ELISA for antibodies to pertussis fimbriae. Confidence Intervals were calculated based on the t-distribution of the log-transformed antibody concentration.

Outcome measures

Outcome measures
Measure	Group Vaxelis (3+1) n=177 Participants Participants previously vaccinated with a 3-dose primary series of Vaxelis® at 2, 3 and 4 months of age, and a toddler dose at 12 months of age (study V419-007). On Day 1 of this extension study (\~4 years after completion of the 3+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.	Group Infanrix Hexa (3+1) n=183 Participants Participants previously vaccinated with a 3-dose primary series of INFANRIX® hexa at 2, 3 and 4 months of age, and a toddler dose at 12 months of age (study V419-007). On Day 1 of this extension study (\~4 years after completion of the 3+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.	Group Vaxelis (2+1) Participants previously vaccinated with a 2-dose primary series of Vaxelis® at 2 and 4 months of age, and a toddler dose at 11-12 months of age (study V419-008). On Day 1 of this extension study (\~4 years after completion of the 2+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.	Group Infanrix Hexa (2+1) Participants previously vaccinated with a 2-dose primary series of INFANRIX® hexa at 2 and 4 months of age, and a toddler dose at 11-12 months of age (study V419-008). On Day 1 of this extension study (\~4 years after completion of the 2+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.
Geometric Mean Concentration of Antibodies to Pertussis Fimbriae	25.99 EU/mL Interval 21.9 to 30.85	2.13 EU/mL Interval 2.01 to 2.25	—	—

OTHER_PRE_SPECIFIED outcome

Timeframe: Up to 4 days following blood sample on Day 1 (approximately 4 years after completion of the 3+1 or 2+1 schedule)

Population: All analyses were performed on the Persistence Analysis Set, defined as all participants previously vaccinated (with a complete 3+1 or 2+1 schedule, as part of studies V419-007 or V419-008) with available immunogenicity data for the respective endpoint.

An SAE is any untoward medical occurrence or effect that at any dose results in death or is life threatening. Life-threatening in this context refers to an event in which the patient was at risk of death at the time of the event; it does not refer to an event which hypothetically might have caused death if it was more severe.

Outcome measures

Outcome measures
Measure	Group Vaxelis (3+1) n=191 Participants Participants previously vaccinated with a 3-dose primary series of Vaxelis® at 2, 3 and 4 months of age, and a toddler dose at 12 months of age (study V419-007). On Day 1 of this extension study (\~4 years after completion of the 3+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.	Group Infanrix Hexa (3+1) n=189 Participants Participants previously vaccinated with a 3-dose primary series of INFANRIX® hexa at 2, 3 and 4 months of age, and a toddler dose at 12 months of age (study V419-007). On Day 1 of this extension study (\~4 years after completion of the 3+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.	Group Vaxelis (2+1) n=181 Participants Participants previously vaccinated with a 2-dose primary series of Vaxelis® at 2 and 4 months of age, and a toddler dose at 11-12 months of age (study V419-008). On Day 1 of this extension study (\~4 years after completion of the 2+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.	Group Infanrix Hexa (2+1) n=191 Participants Participants previously vaccinated with a 2-dose primary series of INFANRIX® hexa at 2 and 4 months of age, and a toddler dose at 11-12 months of age (study V419-008). On Day 1 of this extension study (\~4 years after completion of the 2+1 schedule), a 4 mL blood sample was obtained to assay for long-term antibody persistence.
Percentage of Participants With One or More Serious Adverse Events Related to Study Procedure	0 Percentage of Participants	0 Percentage of Participants	0 Percentage of Participants	0 Percentage of Participants

Adverse Events

Group Vaxelis (3+1)

Serious events: 0 serious events

Other events: 0 other events

Deaths: 0 deaths

Group Infanrix Hexa (3+1)

Serious events: 0 serious events

Other events: 0 other events

Deaths: 0 deaths

Group Vaxelis (2+1)

Serious events: 0 serious events

Other events: 0 other events

Deaths: 0 deaths

Group Infanrix Hexa (2+1)

Serious events: 0 serious events

Other events: 0 other events

Deaths: 0 deaths

Serious adverse events

Adverse event data not reported

Other adverse events

Adverse event data not reported

Additional Information

Senior Vice President, Global Clinical Development

Merck Sharp & Dohme Corp.

Phone: 1-800-672-6372

Email: [email protected]

Results disclosure agreements

Principal investigator is a sponsor employee The Sponsor must have the opportunity to review all proposed abstracts, manuscripts, or presentations based on these study results 60 calendar days prior to submission for publication/presentation. Any information identified by the Sponsor as confidential will be deleted prior to submission. Whenever needed, Sponsor review may be shorter upon agreement between the Sponsor and the authors.
Publication restrictions are in place

Restriction type: OTHER