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RecruitingNCT07097012CosTaRUpdated Oct 22, 2026

Concurrent Versus Sequential Administration of Tdap and RSV Vaccines in Pregnancy

A Phase 4 interventional study of Tdap Vaccine Administration and RSV Vaccine in RSV, Tdap - Tetanus, Diphtheria and Acellular Pertussis Vaccination and Pregnancy, sponsored by Canadian Immunization Research Network. Recruiting at 4 sites in Canada. Open to female participants aged 18 Years to 49 Years. Per ClinicalTrials.gov, last updated 2026-10-22.

Sponsored by Canadian Immunization Research Network · Phase 4, Interventional, and Prevention

From the registry’s dates

  • Started Oct 2025; still recruiting 1 year later.
Updated Oct 22, 2026Primary completion movedSponsor changedGo to Updates ↓
Phase
Phase 4
Study type
Interventional
Enrollment
60
Allocation
Randomized
Ages
18 Years to 49 Years
Sex
Female
01

Study 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.

02

Conditions studied

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

Browse trials for

Keywords

  • RSV
  • Tdap
  • Pregnancy
  • Clinical trial
  • Vaccine
03

In context

Diphtheria

267 studies on the registry are indexed under Diphtheria; 17 are open to participants now.

This study's planned enrollment of 60 is below the median of 448 across 241 interventional studies indexed under Diphtheria.

Browse Diphtheria studies →

Lead sponsor

Canadian Immunization Research Network is the lead sponsor of 11 studies on the registry; 3 are open to participants now.

Counted across the registry records on this site, refreshed daily.

04

Who can participate

Ages eligible
18 Years to 49 Years
Sexes eligible
Female
Accepts healthy volunteers
No

Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.

Inclusion criteria

  1. Healthy pregnant individuals with a singleton pregnancy aged 18-49 years.
  2. 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.
  3. 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).
  4. read, understood and signed prior to study-specific procedures.

Exclusion criteria

Exclusion Criteria

Any of the following:

  1. Receipt of RSV vaccine anytime.
  2. Receipt of immunoglobulins (except Rho D) within 1 year prior to vaccination.
  3. Documented receipt of pertussis vaccine within 2 years prior to vaccination.
  4. Documented pertussis infection (by culture or polymerase chain reaction) within 2 years prior to vaccination.
  5. Receipt of blood transfusion products within 6 months prior to vaccination.
  6. Primary or secondary immunologic disorder or .
  7. 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.
  8. Preconception diabetes mellitus (defined as: previous diagnosis of diabetes while not pregnant OR First trimester level of 6.5% [47.5 mmol/mol] OR First trimester fasting blood glucose 126 mg/dL [7 mmol/L]).
  9. 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).
  10. Congenital anomalies per ultrasound.
  11. infection; infection; Untreated syphilis.
  12. to receipt of Tdap (BOOSTRIX, GSK): a) 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.
  13. Contraindication to receipt of RSVpreF (ABRYSVOTM, Pfizer): Hypersensitivity to the active substance or to any component of the vaccine.

  14. Pregnancy complications at the time of recruitment that are risk factors for preterm delivery:

    1. 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);
    2. 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;
    3. 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. , 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;
    4. 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]);
    5. Placenta anomalies (placenta previa and abruptio, vasa previa);
    6. 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);
    7. Oligohydramnios (decreased amniotic fluid volume as defined in d above);
    8. Short uterine cervix (\<25 mm in the second trimester of pregnancy);
    9. 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.
Terms in these criteria, in plain language(8)

Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.

Informed consent

Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.

You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.

Immunosuppression

A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.

Read whether the line is about a condition or about medicines, and which medicines and doses it means.

HbA1c

A blood test of average blood sugar over the past two to three months, given as a percentage or in mmol/mol. 6.5% (48 mmol/mol) or more is the usual threshold for diabetes, normally confirmed by a second test.

Hepatitis B tests

Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.

Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.

Hepatitis C tests

Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.

After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.

Contraindication

A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.

Hypersensitivity

An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.

Corticosteroids (steroids)

Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.

Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.

05

Study design

Phase
Phase 4
Primary purpose
Prevention
Allocation
Randomized
Intervention model
Crossover assignment
Masking
Quadruple (Participant, Care provider, Investigator, Outcomes assessor)
Enrollment
60 participants (estimated)

Study arms

  • Active comparator
    Group 1: Concurrent Assignment

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

  • Active comparator
    Group 2: Sequential Assignment

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

Interventions

  • BiologicalTdap 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.

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

  • BiologicalRSV 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.

    Also known as: Respiratory syncytial virus, ABRYSVO, RSVpreF

  • OtherSaline (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.

    Also known as: Normal saline

06

What researchers measure

Primary outcomes

  1. 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.

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

  2. 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.

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

  3. 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.

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

  4. 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.

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

Secondary outcomes

  1. 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.

    Time frame: Up to 14 weeks after first vaccination

  2. 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.

    Time frame: Up to 14 weeks after first vaccination

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

    Rates of Serious Adverse Events in Participants during pregnancy and delivery.

    Time frame: Up to 14 weeks after first vaccination

  4. 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.

    Time frame: 4 weeks after vaccination with Tdap

  5. 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.

    Time frame: 4 weeks after vaccination with Tdap

  6. 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.

    Time frame: 4 weeks after vaccination with Tdap

  7. 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.

    Time frame: 4 weeks after vaccination with RSV vaccine

  8. 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.

    Time frame: Up to 14 weeks after vaccination with Tdap

  9. 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.

    Time frame: Up to 14 weeks after vaccination with Tdap

  10. Immunogenicity - Anti-Pertactin IgG levels at term birth (maternal and cord sera)

    Geometric mean concentrations of antibody levels and 95% CI will be calculated.

    Time frame: Up to 14 weeks after vaccination with Tdap

  11. 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.

    Time frame: Up to 14 weeks after vaccination with RSV vaccine

Other outcomes

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

    Anti-B. pertussis IgG in mothers 7 and 19 months after delivery

    Time frame: Months 7 and 19 after delivery

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

    Prefusion RSV F protein IgG in mothers 7 and 19 months after delivery

    Time frame: Months 7 and 19 after delivery

  3. (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

    Anti-B. pertussis IgG in infants at 2, 7 and 19 months of age.

    Time frame: Infants at 2, 7 and 19 months of age

  4. (3) Exploratory: Measurement of anti-RSV antibody levels in breast milk in mothers at 1 week, 2 weeks, 4 weeks and 2 months after delivery following concurrent and sequential administration of vaccines against pertussis and RSV in pregnancy

    Anti-RSV antibody levels in breast milk of others at 1 week, 2 weeks, 4 weeks and 2 months after delivery.

    Time frame: 1 week, 2 weeks, 4 weeks and 2 months after delivery

07

Study locations

3 of 4 sites recruiting
  • Vaccine Evaluation Center
    Vancouver, British Columbia, Canada
    Active, not recruiting

    Not enrolling at this site.

  • Canadian Center for Vaccinology
    Halifax, Nova Scotia, Canada
    Recruiting
    • CCfV Reception - General Inquiries · Contactccfv@iwk.nshealth.ca · 902-470-8141
    • Bahaa Abu-Raya · Principal investigator
  • The Ottawa Hospital Research Institute
    Ottawa, Ontario, Canada
    Recruiting
    • OMNI Research · Contactomniresearch@toh.ca · 613-737-8899
    • Darine El-Chaâr · Principal investigator
  • Centre hospitalier universitaire Ste-Justine
    Montreal, Quebec, Canada
    Recruiting
08

References and documents

Individual participant data

Plan to share: Undecided

No publications or documents are linked to this record.

09

Timeline

1 registry update since Sep 25, 2026
ElapsedEstimatedEstimated, not yet reachedDate before it movedWhere the date was before it movedSimilar studies: half by the dot; the band is the middle halfHalf of similar studies reached it by the dot; the band is the middle half, from a quarter to three quarters

Started Oct 2025 (actual). Primary completion is estimated for Jan 2027, 15 months after the start.

Of 21 phase 4 interventional studies under Diphtheria, half reached primary completion within 22 months of starting (the median), counting those still running; a quarter within 8 and three quarters within 30. This study's planned 15 months is below that.

Primary completion moved once since we started tracking on Sep 25, 2026: Jul 2026 → Jan 2027, on Oct 22, 2026.

Earlier changes are on the record history on ClinicalTrials.gov ↗

How these figures are worked out, and which studies are left out of them.

Registered
Jul 15, 2025
First posted
Jul 31, 2025
StartActual
Oct 16, 2025
Primary completionEst.
Jan 2027was Jul 2026
CompletionEst.
Oct 2027
Last update
Oct 22, 2026
What these dates mean
Start.
When the first participant enrolled; while estimated, when the study expects to open to recruitment.
Primary completion.
When the last participant was examined or treated to collect data for the study's main question, its primary outcome. A study that stopped early gives the date its data collection stopped.
Completion.
When the last participant's last visit took place, for every outcome, secondary ones and side effects included: the end of the study. Often later than primary completion, sometimes the same day.
Actual and Est.
Actual means the registry says the date has happened. Est. (estimated) is a date the sponsor plans or expects. It can still move, and the sponsor is expected to change it to actual once it has passed.
Primary completion
Jul 2026→Jan 2027
Oct 22, 2026
Sponsor
Collaborators added: Sainte Justine Hospital Research Institute; collaborators removed: Centre Hospitalier Univeritaire Sainte Justine
Oct 22, 2026
Show all 1 update
  1. Oct 22, 2026
    Primary completion Jul 2026→Jan 2027
    Sponsor Collaborators added: Sainte Justine Hospital Research Institute; collaborators removed: Centre Hospitalier Univeritaire Sainte Justine
    + 1 other change: verification date

From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗

10

Registry details

Key details

Study ID
NCT07097012
Lead sponsor
Canadian Immunization 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
Bahaa Abu Raya (Principal Investigator, Canadian Immunization Research Network) — Principal investigator
First posted
Jul 31, 2025
Start date
Oct 16, 2025
Primary completion
Jan 2027 (estimated)
Completion
Oct 2027 (estimated)
Last update
Oct 22, 2026

Study contacts

Bahaa Abu-Raya, M.D, PhD
Contact
bh723616@dal.ca
(902) 470-8142
CTN CIRN Central Inbox
Contact
CTN.CIRN@iwk.nshealth.ca
Bahaa Abu-Raya, M.D., PhD
principal investigator · Canadian Center for Vaccinology, Dalhousie University

Oversight

Data monitoring committee
Yes
FDA-regulated drug
No
FDA-regulated device
No
View the source record on ClinicalTrials.gov ↗

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