3rd Dose Study
In 2021 COVID-19 Variants of Concern circulated around the world and there is evidence of some “waning” or decreased effectiveness over time after two doses. Third doses of COVID-19 vaccines have been available in Canada beginning in 2021, and some provinces are providing fourth doses. It is expected that these additional doses will be needed as the virus is will likely circulate in the population for many years.
Eligibility – CURRENTLY ENROLLING
You can take part in this study if:
- You are 18 years of age and older
- You are available for all the study visits.
- You are in good health with stable health conditions.
- You are not pregnant.
- You have a record of your previous doses of the authorized COVID-19 vaccines you received.
There are other study criteria that will be reviewed at the first visit to determine if you are eligible or not.
What will I be asked to do?
You will have 1 vaccine dose, 4 clinic visits and 1 telephone/email contact during a 12-month period. The total time commitment is approximately 2-3 hours.
|Randomized Groups||Vaccine Dose 1||Vaccine Dose 2||Study Vaccine
|1b||Pfizer/BioNTech mRNA||Pfizer/BioNTech mRNA||Pfizer/BioNTech mRNA|
|2b||Pfizer/BioNTech mRNA||Pfizer/BioNTech mRNA||Moderna mRNA|
|3b||Moderna mRNA||Moderna mRNA||Moderna mRNA|
|4b||Moderna mRNA||Moderna mRNA||Pfizer/BioNTech mRNA|
|5b||Moderna mRNA or Pfizer/BioNTech mRNA||Moderna mRNA or Pfizer/BioNTech mRNA1||Moderna mRNA|
|6b||Moderna mRNA or Pfizer/BioNTech mRNA||Moderna mRNA or Pfizer/BioNTech mRNA1||Pfizer/BioNTech mRNA|
|7b||AstraZeneca||Pfizer/BioNTech mRNA or Moderna mRNA2||Pfizer/BioNTech mRNA|
|8b||AstraZeneca||Pfizer/BioNTech mRNA or Moderna mRNA2||Moderna mRNA|
|Previous COVID-19 Doses||Study Vaccine
|9b||2 doses of any authorized COVID-19 Vaccine||Medicago VLP|
In group 5b and 6b the first and second dose can be either mRNA vaccine as long as they are not the same for both doses.
In groups 7b and 8b the second dose can be either mRNA vaccine.
Participants in group 9b who have completed a primary series (2 doses) of any authorized COVID-19 vaccine, with the second dose administered at least 6 months prior, will be enrolled and receive an unblinded single dose of the Medicago VLP vaccine.