Concurrent Versus Sequential Administration of Tdap and RSV Vaccines in Pregnancy

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
• Tdap - Tetanus, Diphtheria and Acellular Pertussis Vaccination
• Pregnancy
• Healthy

Interventions

BIOLOGICAL

Tdap Vaccine Administration

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

BIOLOGICAL

RSV Vaccine

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

OTHER

Saline (as a placebo)

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.

Sponsors & Collaborators

• Ottawa Hospital Research Institute

  collaborator OTHER

• Vaccine Evaluation Center, Canada

  collaborator OTHER

• University of British Columbia

  collaborator OTHER

• Canadian Center for Vaccinology

  collaborator OTHER

• Dalhousie University

  collaborator OTHER

• IWK Health Centre

  collaborator OTHER

• Public Health Agency of Canada (PHAC)

  collaborator OTHER_GOV

• Centre Hospitalier Univeritaire Sainte Justine

  collaborator UNKNOWN

• Canadian Immunization Research Network

  lead NETWORK

Principal Investigators

• Bahaa Abu-Raya, M.D., PhD · Canadian Center for Vaccinology, Dalhousie University

Study Design

Allocation

RANDOMIZED

Purpose

PREVENTION

Masking

QUADRUPLE

Model

CROSSOVER

Eligibility

Min Age

18 Years

Max Age

49 Years

Sex

FEMALE

Healthy Volunteers

No

Timeline & Regulatory

Start

2025-10-16

Primary Completion

2026-05-31

Completion

2027-10-31

Countries

• Canada

Study Locations