National Immunization Awareness Week is a time to recognize the importance of vaccines and their vital role in protecting individuals and communities against infectious diseases. During this week, health professionals and organizations educate the public about vaccines’ benefits and their role in preventing illnesses. 

The Vaccine Evaluation Center (VEC), located at the BC Children’s Hospital Research Institute, is an international leader in vaccine research and the first-of-its-kind center in Canada. The center is jointly supported by BC Children’s Hospital Research Institute and the University of British Columbia.

Dr. Hana Mitchell
Dr. Hana Mitchell is an Investigator and Infectious Disease Pediatrician at BC Children's Hospital and researcher at the Vaccine Evaluation Centre

Dr. Hana Mitchell is an investigator and pediatric infectious diseases specialist at BC Children’s Hospital and the VEC with a research focus on improving the effectiveness of vaccines in patients who may be immunocompromised.

We spoke to Dr. Mitchell about her work and how her interest in translating research findings into day-to-day clinical practice helps to prevent infections in immunocompromised children.

What is the main focus of your work?

As a pediatric infectious diseases specialist at BC Children’s and a researcher at the VEC and the Solid Organ Transplant Research Program, I work with children who received an organ transplant and require lifelong immunosuppression. Solid organ transplantation, which typically includes organs such as the heart, kidneys or liver, is a life-saving treatment for children with organ failure. However, following a transplant, children must take medication to suppress their immune systems so their bodies don’t reject the new organ. This means that vaccines, which depend on a strong immune response, may be less able to fight off infections in these kids. My research focuses on finding out how well vaccines work after organ transplant such as whether COVID-19 vaccinations are still safe and effective for these children.

Why is vaccination and vaccine research important?

Vaccines work by exposing the body to a weakened or inactivated form of a virus or bacteria, which prompts the immune system to produce antibodies. If the person is later exposed to the actual pathogen, their immune system will be able to recognize it and fight it off.

Not only does vaccination protect individuals from getting sick, but it also reduces the likelihood of outbreaks and epidemics.

By achieving herd immunity, where a significant proportion of the population is immune to a disease, we can decrease the likelihood of immune-compromised individuals contracting vaccine-preventable illnesses. 

Historically, vaccines have played a crucial role in preventing the spread of deadly diseases. For example, vaccines have nearly eradicated diseases like smallpox, polio, and measles in many parts of the world.

Getting vaccinated is important for our own safety and also protects the health of others in our community.

What are you working on now?

One of my two main projects is examining the antibody and T-cell responses to the COVID-19 vaccine in children who have received a solid organ transplant. Antibodies are small blood proteins made by immune cells that bind to molecules the body has recognized as a threat, while T-cells are immune cells that can help orchestrate the immune response or directly target other cells infected by a virus. Both components can provide crucial insight into the strength of a child’s immune response.

This study helps us understand how much protection children with transplants receive from vaccination and how long this protection lasts compared to children who have not had transplants. 

Child holding paper heart

I’m also studying the varicella vaccine, which protects against the virus that causes chickenpox and shingles. This vaccine is known as a live-attenuated vaccine, made from a weakened form of the virus. This means that its ability to spread in the body is slowed so that anyone with a relatively healthy immune system should be able to easily fight it off. In the past, children who received an organ transplant were told that the varicella vaccine may not be safe for them. But over the past few years we’ve learned that many children with organ transplants can receive varicella vaccine safely after transplant and gain the necessary protections similar to children without transplant. As a result of our research over the last two years, we have been able to recommend the vaccine to a select number of children in our transplant clinic. As we gain more experience with varicella vaccine after transplant we hope to be able to recommend it to even more children. 

What has been one of the most surprising findings in your research career?

Involving patients and family members as research partners makes research much more meaningful and enjoyable. I am very thankful to the Transplant Research Foundation of BC and the Addison Fund for ensuring patients have a say in how research projects are carried out.