CosTaR – Tdap and RSV vaccines in pregnancy phase 4 pilot feasibility trial

Protecting Babies from Whooping Cough and RSV 

Now that people can receive both Whooping Cough and RSV vaccines during pregnancy, researchers want to find out if giving them at the same visit is safe and effective. This study will also help researchers learn how well the immune system responds and whether pregnant people feel comfortable getting both vaccines at the same time. 

Babies, especially those under 2 months old, are at the highest risk of being hospitalized with whooping cough (pertussis). To help protect them, Canada’s National Advisory Committee on Immunization (NACI) recommends that pregnant people get the Tdap vaccine (which protects against tetanus, diphtheria, and whooping cough) between 27 and 32 weeks of pregnancy.  

Another illness that can be very serious for babies is RSV (respiratory syncytial virus), which can cause severe breathing problems. Nearly 1 in 100 Canadian babies end up in the hospital with RSV in their first year. The rate is even higher in some remote communities. In 2023, Health Canada approved a new RSV vaccine (RSVpreF) for use during 32 to 36 weeks of pregnancy to help protect newborns.  

You may be able to participate in this pilot study if you are:  

• 18-49 years old 
• in good health 
• 20-25 weeks (about 5 and a half months) pregnant 

Other inclusion and exclusion criteria are based on health history. During the screening process, a member of the study team will go over these criteria with you.  

Participants in this study will be randomly selected for one of two groups. Each group will have two study visits. During visit 1, you will receive a single vaccine. There will be two vaccines given during the second visit.

Group 1 (concurrent, or, at the same time) will receive a placebo (saline, a salt-water solution) during their first visit. Four weeks later, during visit 2, participants in this group will receive both the Tdap and RSVpreF  vaccines.

• Visit 1 – Placebo
• Visit 2 – Tdap vaccine & RSV vaccine 

Group 2 

Group 2 (sequential, or, one after the other) will receive the Tdap vaccine during their first visit. Four weeks later, during visit 2, participants in this group will receive a placebo (saline, a salt-water solution) and the RSVpreF vaccine.  

• Visit 1 – Tdap vaccine
• Visit 2 – Placebo & RSV vaccine

Participants will not know which group they are a part of until the end of the study period.  

• The Tdap vaccine is part of routine care in all provinces. 

• RSVpreF is approved but not publicly funded in all provinces. Where is it not funded, the vaccine can be purchased and is covered by most health plans.