About Our Study


There are some individuals who have low or compromised immune systems due to genetics or medications being taken to treat various health conditions. These individuals are at a significantly greater health risk of developing severe COVID-19 infections compared to the general population.

COVID-19 vaccines are being offered to all eligible Canadians to provide immunity against the SARS-COV-2 virus. However, the clinical trials for these vaccines did not include individuals with low or compromised immune systems. Hence, it is not known how these individuals will respond to these COVID-19 vaccines. The purpose of our study is to fill this gap in knowledge by increasing our understanding of immunocompromised individuals’ response to COVID-19 vaccines and studying the effectiveness and safety of COVID-19 vaccines in this group. This knowledge will inform healthcare practitioners’ decisions with regard to administering COVID-19 vaccines for this group. Additionally, examining the immune responses in individuals with many different kinds of immune system problems will help our investigators tease out which component of the immune system is essential to the normal COVID-19 vaccine response.


The proposed study will address how well people with low immune systems respond to COVID-19 vaccines and how safe the vaccines are for this population, in comparison to healthy individuals. In order to assess the participant’s immune response to COVID-19, we will collect blood samples from participants at specific time periods before and after receiving their first, second, third and fourth (if applicable doses of the vaccine. We will use these blood samples to measure the antibody levels against the SARS-COV-2 virus and evaluate how well these antibodies function i.e., how well the antibodies prevent the COVID-19 virus from entering human cells. We will also measure another component of the immune system, known as cellular mediated immunity or T-cell response, by determining how many T-cells that produce a protein in response to SARS-CoV-2 are present in the blood sample. The antibody levels and T-cell response will be compared before and after vaccination in people with low immune systems and healthy individuals. To evaluate safety, we will monitor for adverse events (side effects) following immunization with online questionnaires as well as over-the-phone and in-person follow-up appointments with healthcare professionals.

I am interested in participating, what’s involved?

Thank you for your interest in joining our study! As a study participant, you would:

  • Complete online questionnaires
  • Visit The Ottawa Hospital or participating vaccination clinic to receive first, second, third and fourth (if applicable) COVID-19 vaccination doses if you have not already received them.
  • Where applicable, have bloodwork drawn up to 28 days before your first vaccine, 4-12 weeks after your first dose but before your second dose, 6-24 weeks after the second dose but before your third dose, 6-24 weeks after the third dose but before the fourth dose, and 24 weeks after your fourth dose. We will use the results from your bloodwork to assess your immune system’s response to the vaccine. Please note that the number of study visits and bloodwork will depend on where the participant is at in their vaccine series as well as whether the participant is an adult or a child. This study does not currently include second booster doses (fourth doses for healthy participants or fifth doses for immunocompromised participants).
  • Attend an initial virtual/in-person visit