Concurrent Versus Sequential Administration of Tdap and RSV Vaccines in Pregnancy

Not Applicable

Not yet recruiting

• Conditions: RSV; Tdap - Tetanus, Diphtheria and Acellular Pertussis Vaccination; Pregnancy; Healthy
• Interventions: Biological: Tdap Vaccine Administration; Biological: RSV Vaccine; Other: Saline (as a placebo)

• Registration Number: NCT07097012
• Lead Sponsor: Canadian Immunization Research Network

Brief Summary

The goal of this clinical trial is to learn if the RSV vaccine (protects against respiratory syncytial virus) and Tdap vaccine (protects against pertussis) are most effective in pregnant individuals when taken together at the same visit, or separately at different visits. This clinical trial will also learn about the safety and immune responses of these vaccines in pregnancy.

The Main question:

-Is it possible to run a successful trial that tests how safe and effective it is to give Tdap and RSV vaccines in pregnancy either at the same time or one after the other, at different visits?

The Secondary question:

-To determine how safe and how well the Tdap and RSV vaccines work when given in pregnancy either at the same time or one after the other, at different visits.

The Exploratory (optional participation) questions:

* To measure the levels of antibodies against whooping cough (pertussis) and RSV in mothers at 7 and 19 months after giving birth, depending on whether they got the vaccines at the same time or one after the other during pregnancy.

* To measure whooping cough antibody levels in the babies at 2, 7, and 19 months of age, whose mothers who received the vaccines in pregnancy.

* To measure the levels of RSV antibodies in the mothers' breast milk at 1 week, 2 weeks, 4 weeks, and 2 months after giving birth.

Participants will be randomly assigned to Group 1 (vaccines given at the same time, same visit) or Group 2 (vaccines given one after the other, at different visits).

There are 4 visits as part of the main study, and 6 additional visits as part of the optional study (exploratory questions).

Visit 1-2: Blood collection and vaccines administered Visit 3-4: Blood work (cord blood sample collection from infant, after delivery, if possible) Visit 5-8: Breast milk collection Visit 8-10: Blood collection (infant blood collection only at Visit 8).

Participants will be asked to keep a diary of symptoms throughout the study.

Detailed Description

Not available

Study Timeline

• Status Verified: 2025-07
• Study First Submitted: 2025-07-15
• Study First Submitted QC: 2025-07-24
• Last Update Submitted: 2025-07-24
• Study First Posted: 2025-07-31
• Last Update Posted: 2025-07-31
• Study Start: 2025-09-01
• Primary Completion: 2026-01
• Study Completion: 2027-10-01

Recruitment & Eligibility

• Status: NOT_YET_RECRUITING
• Sex: Female
• Target Recruitment: 60

Inclusion Criteria

Not provided

Exclusion Criteria

Not provided

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: CROSSOVER

Arm && Interventions

Group	Intervention	Description
Group 1: Concurrent Assignment	Tdap Vaccine Administration	-
Group 2: Sequential Assignment	RSV Vaccine	-
Group 1: Concurrent Assignment	RSV Vaccine	-
Group 1: Concurrent Assignment	Saline (as a placebo)	-
Group 2: Sequential Assignment	Saline (as a placebo)	-
Group 2: Sequential Assignment	Tdap Vaccine Administration	-

Primary Outcome Measures

Name	Time	Method
Feasibility of conducting a randomized controlled trial - Screening Rate	From enrollment to the end of visit 4 (end of main study) at around 12 weeks	To evaluate the feasibility of conducting a randomized controlled trial (RCT) that would test the safety and immunogenicity of Tdap and RSV concurrent and sequential administration in pregnancy.; Number of participants screened monthly in each site and overall.
Feasibility of conducting a randomized controlled trial - Consent & Randomization Rate	From enrollment to the end of visit 4 (end of main study) at around 12 weeks	To evaluate the feasibility of conducting a randomized controlled trial (RCT) that would test the safety and immunogenicity of Tdap and RSV concurrent and sequential administration in pregnancy.; Proportion/number of participants who consent and successfully randomized out of screened individuals in each site and overall.
Feasibility of conducting a randomized controlled trial - Retention Rate	From enrollment to the end of visit 4 (end of main study) at around 12 weeks	To evaluate the feasibility of conducting a randomized controlled trial (RCT) that would test the safety and immunogenicity of Tdap and RSV concurrent and sequential administration in pregnancy.; Proportion of randomized participants who complete the first four study visits in each site and overall.
Feasibility of conducting a randomized controlled trial - Trial Protocol Compliance Rate	From enrollment to the end of visit 4 (end of main study) at around 12 weeks	To evaluate the feasibility of conducting a randomized controlled trial (RCT) that would test the safety and immunogenicity of Tdap and RSV concurrent and sequential administration in pregnancy.; Percentage of participants who do not deviate from the protocol and complete vaccination and the first four visits in each site and overall.

Secondary Outcome Measures

Name	Time	Method
Safety Outcomes - Rates of Adverse Events Following Immunization in Participants	Up to 14 weeks after first vaccination	In this study, an adverse event will be categorized as an AEFI if it meets the relevant provincial reporting criteria and occurs after vaccination and up until delivery.; Rates of Adverse Events Following Immunization in Participants.
Safety Outcomes - Rates of Adverse Events of Special Interest in Participants during Pregnancy and Delivery	Up to 14 weeks after first vaccination	Rates of Adverse Events of Special Interest in Participants during pregnancy and delivery.
Safety Outcomes - Rates of Serious Adverse Events in Participants during Pregnancy and Delivery	Up to 14 weeks after first vaccination	Rates of Serious Adverse Events in Participants during pregnancy and delivery.
Immunogenicity - Seroconversion rate of anti-pertussis toxin IgG	4 weeks after vaccination with Tdap	Seroconversion rate of anti-pertussis toxin IgG 4 weeks after vaccination with Tdap vaccine in the concurrent versus sequential groups.; For the secondary immunogenicity outcome, fold change in antibody levels between pre-vaccination and 4-weeks after vaccination will be calculated. Seroconversion rates and their 95% CI will be calculated and described. Geometric mean concentrations of antibody levels and 95% CI will be calculated.
Immunogenicity - Seroconversion rate of anti-Filamentous hemagglutinin IgG	4 weeks after vaccination with Tdap	Seroconversion rate of anti-Filamentous hemagglutinin IgG 4 weeks after vaccination with Tdap vaccine in the concurrent versus sequential groups.; For the secondary immunogenicity outcome, fold change in antibody levels between pre-vaccination and 4-weeks after vaccination will be calculated. Seroconversion rates and their 95% CI will be calculated and described. Geometric mean concentrations of antibody levels and 95% CI will be calculated.
Immunogenicity - Seroconversion rate of anti-Pertactin IgG	4 weeks after vaccination with Tdap	Seroconversion rate of anti-Pertactin IgG 4 weeks after vaccination with Tdap vaccine in the concurrent versus sequential groups.; For the secondary immunogenicity outcome, fold change in antibody levels between pre-vaccination and 4-weeks after vaccination will be calculated. Seroconversion rates and their 95% CI will be calculated and described. Geometric mean concentrations of antibody levels and 95% CI will be calculated.
Immunogenicity - Seroconversion rate of Prefusion RSV F protein IgG	4 weeks after vaccination with RSV vaccine	Seroconversion rate of Prefusion RSV F protein IgG 4 weeks after vaccination with RSV vaccine in the concurrent versus sequential groups.; For the secondary immunogenicity outcome, fold change in antibody levels between pre-vaccination and 4-weeks after vaccination will be calculated. Seroconversion rates and their 95% CI will be calculated and described. Geometric mean concentrations of antibody levels and 95% CI will be calculated.
Immunogenicity - Anti-Pertussis toxin IgG levels at term birth (maternal and cord sera)	Up to 14 weeks after vaccination with Tdap	Geometric mean concentrations of antibody levels and 95% CI will be calculated.
Immunogenicity - Anti-Filamentous hemagglutinin IgG levels at term birth (maternal and cord sera)	Up to 14 weeks after vaccination with Tdap	Geometric mean concentrations of antibody levels and 95% CI will be calculated.
Immunogenicity - Anti-Pertactin IgG levels at term birth (maternal and cord sera)	Up to 14 weeks after vaccination with Tdap	Geometric mean concentrations of antibody levels and 95% CI will be calculated.
Immunogenicity - Prefusion RSV F protein IgG levels at term birth (maternal and cord sera)	Up to 14 weeks after vaccination with RSV vaccine	Geometric mean concentrations of antibody levels and 95% CI will be calculated.

Trial Locations

Locations (4)

Vaccine Evaluation Center; 🇨🇦 Vancouver, British Columbia, Canada

Canadian Center for Vaccinology; 🇨🇦 Halifax, Nova Scotia, Canada

The Ottawa Hospital Research Institute; 🇨🇦 Ottawa, Ontario, Canada

Centre hospitalier universitaire Ste-Justine; 🇨🇦 Montréal, Quebec, Canada