Thank you, Chair, and thank you to the honourable members of the committee for the opportunity to speak this morning.
I'd like to start off by just saying that the thoughts I'm presenting are really my own as a translational immunologist, and not necessarily those that are shared by my affiliated organizations.
My focus today is really on two issues.
The first is the apparent lack of strategy we had of ensuring that Canadians have a diverse portfolio of the types of vaccines we have in our tool box at this time. We have definitely procured a good number of vaccines and this is fantastic, but they're all of the new gene delivery platform variety, and I'll be elaborating a little bit on that subsequently.
Second is our apparent neglect to consider sex differences in immune response to infections and vaccinations in our strategy for immune protection.
To understand the first issue, I will provide a brief overview of the three broad categories of vaccines.
The first is whole vaccines and these come in two flavours. First is the live-attenuated vaccine, which provides a really fulsome training for the immune system. The one infectious disease that we have successfully eradicated through vaccination, smallpox, was done using a live-attenuated vaccine. These provide longer lasting immunity and they typically don't require multiple booster shots. I would say these are the best options for young, healthy kids. However, they take quite a while to produce.
The second type of whole vaccine is the whole inactivated vaccines. These are fairly straightforward to make. They don't take very long at all. It's essentially the whole microbe that's killed in some way. We already have one that has been approved for emergency use for COVID-19 by the World Health Organization. These whole vaccines, because of their multiple epitopes, are theoretically really less susceptible to result in a loss of efficacy with variants or aid in variants selection.
The second category of vaccines is what we call component, or subunit, vaccines. They're made by selecting immunogenic parts of a microbe and formulating these with an adjuvant. You can consider them to be highly processed versions of a double inactivated vaccine.
We have a lot of experience using the above types of vaccines for generating immune protection. In fact, the first category we've used for centuries, which really makes it easier to make educated guesses about their effects and also anticipating any safety concerns we may have.
The third category is these new cool nucleic acid delivery platforms that we have rolled out, which deliver genetic material either in the form of DNA or RNA into our cells to make or express viral proteins. We have very little, to no, knowledge on the long-term safety and efficacy of many aspects of this particular technology, especially when these vaccines are given in multiple doses. Given this lack of experience, it is very difficult to make well-informed decisions regarding their use. We've seen this play out in real time during the pandemic.
Given the above, why are all the options Canadians currently have in our tool box for immune protection in the midst of a pandemic all based on a technology in which we have the least experience and which have never been approved outside of emergency use authorization? I think we need to understand that issue a little bit more.
That leads me to the second issue. Not only do we need access to a diverse portfolio of vaccines to de-risk our response to the pandemic, but we should really strive to understand which vaccines would best serve different populations with different risk profiles.
To this point, I'd like to bring attention to sex differences that have been largely ignored, despite a very long history of sex-discrepant outcomes to infections and vaccine-associated adverse effects. This would be a prime example in which the implementation of GBA+, for example, would be highly relevant.
We know cis men are known to be, on average, more susceptible to severe infections, and we've seen that in the COVID-19 mortality data. Cis women, on the other hand, have a much stronger immune response, and this more vigorous immunity is a double-edged sword. Being female is also the greatest predictive risk factor for many autoimmune diseases. Women also bear the brunt of experiencing more serious adverse events related to vaccination, and we've also seen that with the COVID-19 vaccines.
Of note, a study has shown that women receiving half the flu dose generate a higher level of immune response compared to men who receive a typical or standard dose of the vaccine.
Given this body of knowledge, we should, at minium I think, be requesting that sex-based dosing studies for these new gene delivery platforms be performed for both safety and efficacy.
Thank you again for your time and considering these issues.