RSVPhase 4CosTaRNCT07097012
Concurrent Versus Sequential Administration of Tdap and RSV Vaccines in Pregnancy
A Phase 4 study testing Tdap Vaccine Administration and RSV Vaccine in people with RSV and Tdap - Tetanus, Diphtheria and Acellular Pertussis Vaccination, run by Canadian Immunization Research Network at 4 sites in Canada.
Trial 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. Read more about this study
- Who is it for?
- Ages 18 to 49 years, women only
- Conditions the study is for
- RSV, Tdap - Tetanus, Diphtheria and Acellular Pertussis Vaccination, Pregnancy
- What is being tested?
- Tdap Vaccine Administration and RSV Vaccine
- Type of treatment
- Vaccines
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 60 participants
- Where
- 4 sitesCanada
- Study dates
- 16 Oct 2025to Oct 2027
- Phase
- Phase 4
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 49 years
- Women only
- No healthy volunteers
- Adult
Who may be able to join
- 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.
- Able to comply with the study procedures required to achieve primary objective of this pilot trial (not being able to comply with procedures required to achieve exploratory objectives is not an exclusion criteria).
- Informed consent read, understood and signed prior to study-specific procedures.
Who cannot join
- 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.
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- 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.
- Pregnancy complications at the time of recruitment that are risk factors for preterm delivery:
- Gestational hypertension (defined as new onset hypertension after 20 WG of systolic blood pressure is ≥140 mmHg or the diastolic blood pressure is ≥90 mmHg on two measurements at a minimum of one hour apart);
- Pre-eclampsia (defined as development of gestational hypertension [as defined in #a above] and proteinuria after 20 WG (Proteinuria defined as ≥300 mg in a 24 h urine specimen, or ≥0.30 on a spot protein: creatinine ratio, or ≥1+ on a dipstick;
- Gestational diabetes mellitus uncontrolled at time of consent (gestational diabetes is defined as a clinical syndrome characterized by the absence of preconception diabetes mellitus [as defined in #8 above] AND identification of sustained hyperglycemia during pregnancy not due to other known causes (i.e. corticosteroids, beta-mimetics, etc.) based on positive internationally recognized oral glucose tolerance test OR fasting plasma glucose of 92-125 mg/dL [5.1-6.9 mmol/l] using venous or capillary blood samples;
- Fetal growth restriction (defined as estimated fetal weight below 10% using locally-accepted growth curve AND Absent or reversed end-diastolic flow of the umbilical artery Doppler OR Oligohydramnios [defined as a decreased amniotic fluid volume as defined by amniotic fluid index less than 8 cm or deepest vertical pocket less than 2 cm in the presence of intact membranes without concern for fetal anomalies contributing to its etiology]);
- Placenta anomalies (placenta previa and abruptio, vasa previa);
- Polyhydramnios (defined as abnormal increase in the volume of amniotic fluid as either a deepest vertical pocket of ≥8 cm or an amniotic fluid index of ≥24 cm);
- Oligohydramnios (decreased amniotic fluid volume as defined in d above);
- Short uterine cervix (<25 mm in the second trimester of pregnancy);
- A significant acute disease or oral temperature ≥38 Co within 24 hours prior to vaccination. Participants can return for evaluation to be randomized/vaccinated 72 hours after symptoms resolve, if they are still within 28-29+6 WG.
Trial locations and contacts
4 sites in 1 country. Contact the study team or a site near you to ask about taking part.
CTN CIRN Central Inbox contact
Canada4 sites, 3 recruiting
- Recruiting
Canadian Center for Vaccinology
Halifax, Nova Scotia
CCfV Reception - General Inquiries, 902-470-8141, ccfv@iwk.nshealth.ca
Bahaa Abu-Raya
- Recruiting
Centre hospitalier universitaire Ste-Justine
Montreal, Quebec
Hasna Meddour (Project Manager), 514-345-4931 ext. 7169, hasna.meddour.hsj@ssss.gouv.qc.ca
Isabelle Boucoiran
- Recruiting
The Ottawa Hospital Research Institute
Ottawa, Ontario
OMNI Research, 613-737-8899 ext. 73182, omniresearch@toh.ca
Darine El-Chaâr
- Active, not recruiting
Vaccine Evaluation Center
Vancouver, British Columbia
About this study
Official title: Concurrent Versus Sequential Administration of Tdap and RSV Vaccines in Pregnancy - A Pilot Feasibility Trial
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:
Read more
-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.
- Being tested
- Tdap Vaccine Administration, RSV Vaccine, Saline (as a placebo)
- Keywords
- RSV, Tdap, Pregnancy, Clinical trial, Vaccine
- Medical subject headings
- Diphtheria
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Tdap Vaccine AdministrationBiological
Also called BOOSTRIX, Tetanus-diphtheria-acellular pertussis
The Tdap vaccine will be administered according to the Product Monograph. Participants will be asked to look away during vaccine administration to maintain blinding.
RSV VaccineBiological
Also called Respiratory syncytial virus, ABRYSVO, RSVpreF
The RSVpreF vaccine will be administered according to the Product Monograph. Participants will be asked to look away during vaccine administration to maintain blinding.
Saline (as a placebo)Other
Also called Normal saline
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.
| Study group | Role | What they receive |
|---|---|---|
| Group 1: Concurrent Assignment | Active comparator | Not described Receives: Biological: Tdap Vaccine Administration; Biological: RSV Vaccine; Other: Saline (as a placebo) |
| Group 2: Sequential Assignment | Active comparator | Not described Receives: Biological: Tdap Vaccine Administration; Biological: RSV Vaccine; Other: Saline (as a placebo) |
What is being measured
The primary outcome is the main question the study is designed to answer.
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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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
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.
Measured: Up to 14 weeks after first vaccination
Safety Outcomes - Rates of Adverse Events of Special Interest in Participants during Pregnancy and Delivery
Rates of Adverse Events of Special Interest in Participants during pregnancy and delivery.
Measured: Up to 14 weeks after first vaccination
Safety Outcomes - Rates of Serious Adverse Events in Participants during Pregnancy and Delivery
Rates of Serious Adverse Events in Participants during pregnancy and delivery.
Measured: Up to 14 weeks after first vaccination
Immunogenicity - Seroconversion rate of anti-pertussis toxin IgG
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.
Measured: 4 weeks after vaccination with Tdap
Immunogenicity - Seroconversion rate of anti-Filamentous hemagglutinin IgG
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.
Measured: 4 weeks after vaccination with Tdap
Immunogenicity - Seroconversion rate of anti-Pertactin IgG
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.
Measured: 4 weeks after vaccination with Tdap
Immunogenicity - Seroconversion rate of Prefusion RSV F protein IgG
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.
Measured: 4 weeks after vaccination with RSV vaccine
Immunogenicity - Anti-Pertussis toxin IgG levels at term birth (maternal and cord sera)
Geometric mean concentrations of antibody levels and 95% CI will be calculated.
Measured: Up to 14 weeks after vaccination with Tdap
Immunogenicity - Anti-Filamentous hemagglutinin IgG levels at term birth (maternal and cord sera)
Geometric mean concentrations of antibody levels and 95% CI will be calculated.
Measured: Up to 14 weeks after vaccination with Tdap
Immunogenicity - Anti-Pertactin IgG levels at term birth (maternal and cord sera)
Geometric mean concentrations of antibody levels and 95% CI will be calculated.
Measured: Up to 14 weeks after vaccination with Tdap
Immunogenicity - Prefusion RSV F protein IgG levels at term birth (maternal and cord sera)
Geometric mean concentrations of antibody levels and 95% CI will be calculated.
Measured: Up to 14 weeks after vaccination with RSV vaccine
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted31 Jul 2025
- Study start16 Oct 2025
- Primary completionJan 2027 (estimated)
- Study completionOct 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for RSVStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 4
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Quadruple blind
- Who is masked
- Participant, Care provider, Investigator, Outcomes assessor
- Enrolment
- 60 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Canadian Immunization Research Network
- Sponsor type
- Research network
- Collaborators
- Ottawa Hospital Research Institute, Vaccine Evaluation Center, Canada, University of British Columbia, Canadian Center for Vaccinology, Dalhousie University, IWK Health Centre, Public Health Agency of Canada (PHAC), Sainte Justine Hospital Research Institute
- Responsible party
- Principal investigator, Bahaa Abu Raya, Canadian Immunization Research Network
- Investigators
- Bahaa Abu-Raya, M.D., PhD, Principal investigator, Canadian Center for Vaccinology, Dalhousie University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07097012
- Sponsor's protocol ID
- CT25
- Acronym
- CosTaR
- Status last verified
- Oct 2026
- First submitted
- 15 Jul 2025
- Last updated
- 22 Oct 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Undecided