Concurrent Versus Sequential Administration of Tdap and RSV Vaccines in Pregnancy

NCT07097012 | Recruiting Phase 4 DMC

• 1 other identifier: CT25
• Study Type: interventional
• Target: 60
• Locations: 1 country
• Sites: 4

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.

Conditions

RSV; Pregnancy; Healthy; Tdap - Tetanus, Diphtheria and Acellular Pertussis Vaccination

Keywords

RSV; Tdap; Pregnancy; Clinical trial; Vaccine

Outcome Measures

Primary Outcomes (4)

• Feasibility of conducting a randomized controlled trial - Screening Rate

  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.

  From enrollment to the end of visit 4 (end of main study) at around 12 weeks

• Feasibility of conducting a randomized controlled trial - Consent & Randomization Rate

  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.

  From enrollment to the end of visit 4 (end of main study) at around 12 weeks

• Feasibility of conducting a randomized controlled trial - Retention Rate

  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.

  From enrollment to the end of visit 4 (end of main study) at around 12 weeks

• Feasibility of conducting a randomized controlled trial - Trial Protocol Compliance Rate

  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.

  From enrollment to the end of visit 4 (end of main study) at around 12 weeks

Secondary Outcomes (11)

• Safety Outcomes - Rates of Adverse Events Following Immunization in Participants

  Up to 14 weeks after first vaccination

• Safety Outcomes - Rates of Adverse Events of Special Interest in Participants during Pregnancy and Delivery

  Up to 14 weeks after first vaccination

• Safety Outcomes - Rates of Serious Adverse Events in Participants during Pregnancy and Delivery

  Up to 14 weeks after first vaccination

• Immunogenicity - Seroconversion rate of anti-pertussis toxin IgG

  4 weeks after vaccination with Tdap

• Immunogenicity - Seroconversion rate of anti-Filamentous hemagglutinin IgG

  4 weeks after vaccination with Tdap

Other Outcomes (4)

• (1) Exploratory: Measurement of anti-B. pertussis responses in mothers 7 and 19 months after delivery

  Months 7 and 19 after delivery

• (1) Exploratory: Measurement of RSV antibody responses in mothers 7 and 19 months after delivery

  Months 7 and 19 after delivery

• (2) Exploratory: Measurement of anti-B. pertussis antibody levels in infants at 2, 7 and 19 months of age born to mothers who received concurrent and sequential administration of vaccines against pertussis and RSV in pregnancy

  Infants at 2, 7 and 19 months of age

Study Arms (2)

Group 1: Concurrent Assignment

ACTIVE COMPARATOR

Biological: Tdap Vaccine Administration; Biological: RSV Vaccine; Other: Saline (as a placebo)

Group 2: Sequential Assignment

ACTIVE COMPARATOR

Biological: Tdap Vaccine Administration; Biological: RSV Vaccine; Other: Saline (as a placebo)

Interventions

Tdap Vaccine Administration BIOLOGICAL

The Tdap vaccine will be administered according to the Product Monograph. Participants will be asked to look away during vaccine administration to maintain blinding.

Also known as: BOOSTRIX, Tetanus-diphtheria-acellular pertussis

Group 1: Concurrent Assignment; Group 2: Sequential Assignment

RSV Vaccine BIOLOGICAL

The RSVpreF vaccine will be administered according to the Product Monograph. Participants will be asked to look away during vaccine administration to maintain blinding.

Also known as: Respiratory syncytial virus, ABRYSVO, RSVpreF

Group 1: Concurrent Assignment; Group 2: Sequential Assignment

Saline (as a placebo) OTHER

Normal saline (0.5mL) will be administered as a placebo according to the Product Monograph. Participants will be asked to look away during vaccine administration to maintain blinding.

Also known as: Normal saline

Group 1: Concurrent Assignment; Group 2: Sequential Assignment

Eligibility Criteria

• Age: 18 Years - 49 Years
• Sex: female
• Healthy Volunteers: No
• Age Groups: Adult (18-64)

You may qualify if:

• Healthy pregnant individuals with a singleton pregnancy aged 18-49 years.
• Gestational age 28-29+6 WG at time of study screening, enrolment and randomization as per documented first trimester (less than or equal to13+6 WG) ultrasound, or the first date of last menstrual period if ultrasound not obtained in the first trimester, or the age of the embryo and the date of transfer if pregnancy resulted from assisted reproductive technology.

You may not qualify if:

• Informed consent read, understood and signed prior to study-specific procedures.
• Any of the following:
• Receipt of RSV vaccine anytime.
• Receipt of immunoglobulins (except Rho D) within 1 year prior to vaccination.
• Documented receipt of pertussis vaccine within 2 years prior to vaccination.
• Documented pertussis infection (by culture or polymerase chain reaction) within 2 years prior to vaccination.
• Receipt of blood transfusion products within 6 months prior to vaccination.
• Primary or secondary immunologic disorder or immunosuppression.
• Any conditions that, in the investigator's judgement, may interfere with subject's ability to comply with study procedures or receipt of prenatal care, such as behavioural or cognitive impairment or neuropsychiatric illness.
• Preconception diabetes mellitus (defined as: previous diagnosis of diabetes while not pregnant OR First trimester hemoglobin A1c level of 6.5% \[47.5 mmol/mol\] OR First trimester fasting blood glucose 126 mg/dL \[7 mmol/L\]).
• Preconception chronic hypertension (defined as: sustained elevation in the systolic blood pressure to ≥140 mmHg or the diastolic blood pressure to ≥90 mmHg, that is diagnosed either prior to pregnancy or prior to 20 WG).
• Congenital anomalies per ultrasound.
• Hepatitis B infection; Hepatitis C infection; Untreated syphilis.
• Contraindication to receipt of Tdap (BOOSTRIX, GSK): a) Hypersensitivity to any component of the Tdap (BOOSTRIX, GSK) vaccine or individuals having shown signs of hypersensitivity after previous administration of diphtheria, tetanus, or pertussis vaccines; b) Encephalopathy of unknown etiology, occurring within 7 days following previous vaccination with pertussis containing vaccine; c) Transient thrombocytopenia or neurological complications following an earlier immunization against diphtheria and/or tetanus.
• Contraindication to receipt of RSVpreF (ABRYSVOTM, Pfizer): Hypersensitivity to the active substance or to any component of the vaccine.

Sponsors & Collaborators

• Ottawa Hospital Research Institute: collaborator
• Vaccine Evaluation Center, Canada: collaborator
• University of British Columbia: collaborator
• Canadian Center for Vaccinology: collaborator
• IWK Health Centre: collaborator
• Public Health Agency of Canada (PHAC): collaborator
• Centre Hospitalier Univeritaire Sainte Justine: collaborator
• Canadian Immunization Research Network: lead
• Dalhousie University: collaborator

Study Sites (4)

Vaccine Evaluation Center

Vancouver, British Columbia, Canada

RECRUITING

Canadian Center for Vaccinology

Halifax, Nova Scotia, Canada

RECRUITING

The Ottawa Hospital Research Institute

Ottawa, Ontario, Canada

RECRUITING

Centre hospitalier universitaire Ste-Justine

Montreal, Quebec, Canada

RECRUITING

MeSH Terms

Conditions

Diphtheria

Interventions

Boostrix; Respiratory Syncytial Virus Vaccines; abrysvo; Sodium Chloride; Saline Solution

Condition Hierarchy (Ancestors)

Corynebacterium Infections; Actinomycetales Infections; Gram-Positive Bacterial Infections; Bacterial Infections; Bacterial Infections and Mycoses; Infections

Intervention Hierarchy (Ancestors)

Viral Vaccines; Vaccines; Biological Products; Complex Mixtures; Chlorides; Hydrochloric Acid; Chlorine Compounds; Inorganic Chemicals; Sodium Compounds; Crystalloid Solutions; Isotonic Solutions; Solutions; Pharmaceutical Preparations

Study Officials

• Bahaa Abu-Raya, M.D., PhD

  Canadian Center for Vaccinology, Dalhousie University

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Bahaa Abu-Raya, M.D, PhD

CONTACT

(902) 470-8142; bh723616@dal.ca

CTN CIRN Central Inbox

CONTACT

CTN.CIRN@iwk.nshealth.ca

Study Design

• Study Type: interventional
• Phase: phase 4
• Allocation: RANDOMIZED
• Masking: QUADRUPLE
• Who Masked: PARTICIPANT, CARE PROVIDER, INVESTIGATOR, OUTCOMES ASSESSOR
• Masking Details: Data Safety Monitoring Board members, unless unblinding is required to provide a comprehensive safety assessment.
• Purpose: PREVENTION
• Intervention Model: CROSSOVER
• Sponsor Type: NETWORK
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Principal Investigator

Study Record Dates

• First Submitted: July 15, 2025
• First Posted: July 31, 2025
• Study Start: October 16, 2025
• Primary Completion: May 1, 2026
• Study Completion (Estimated): October 1, 2027
• Last Updated: March 12, 2026

Record last verified: 2026-03

Locations

CA (4)