e-2845 (Human diseases)

Health Canada thanks the petitioners for taking the time to raise the important topic of human challenge trials in the context of development of vaccines to prevent infection with SARS-CoV-2, the virus that causes COVID-19.  The Government of Canada recognizes the critical impact COVID-19 is having on the lives of all Canadians, both from a health and economic perspective, and continues to take measures to respond to the pandemic with the highest priority. Providing access for Canadians to safe, high quality and effective vaccines is an important part of our overall response. Since the pandemic began, Health Canada has engaged with  stakeholders, including vaccine manufacturers, to provide regulatory assistance in the development of vaccines and treatments.  Globally, large clinical trials for COVID-19 vaccines are ongoing, enrolling tens of thousands of participants; these trials are expected to provide the data required to determine whether these vaccines are safe and effective. In addition, Health Canada has authorized a number of clinical trials for vaccines and treatments in Canada, and is already conducting in-depth reviews of submissions for market authorization of three leading COVID-19 vaccines. 

The ongoing large clinical trials for the leading vaccines are progressing, with the objective of having results available as soon as possible to confirm the efficacy and safety of these vaccines.  Once the results become available, they will be submitted to Health Canada under its rolling review process.  The Department is committed to reviewing all COVID-19 vaccines in an expedited manner while maintaining high standards for the safety, efficacy, and quality evidence required for authorizations.  In parallel, the Public Health Agency of Canada is elaborating a vaccine deployment strategy to ensure vaccines can be distributed and made available to Canadians soon after regulatory authorization is issued.  The Government of Canada has also concluded agreements that will guarantee access for Canadians millions of doses of the most promising vaccine candidates.

For a human challenge trial to be authorized in Canada, a clinical trial application would need to be filed with Health Canada for review.  Under the Food and Drug Regulations, a clinical trial must be conducted according to good clinical practices, with approval from a research ethics board, informed participant consent, and extensive safety monitoring to protect participants. More specifically, stringent safety and ethical requirements would need to be met, including but not limited to:

• clear informed consent for all participants, where they are explained the potential risks and anticipated benefits;
• maintenance of participants’ safety, including through the availability of medical assistance and appropriate effective treatments should they become ill;
• consideration to using a weakened version of the SARS-CoV-2 virus to further reduce the risks to participants;
• measures to effectively minimize the potential transmission of the SARS-CoV-2 virus to third parties, given how infectious it is;
• a study design that will clearly meet its objectives and have an impact on public health, and produce reliable and relevant data; and
• consideration as to whether there are alternative means to gathering the same information.

Health Canada can object to a trial if it determines that it will endanger trial participants or others, that it is not in the best interests of participants, or that its objectives will not be achieved.

Health Canada considers that a human challenge trial for COVID-19 would involve a higher risk since SARS-CoV-2 is a new virus that we are still learning about, and long-term effects of the virus are still unknown. With COVID-19, the illness can be severe and deadly, sometimes even in young and healthy individuals, and only limited supportive treatments exist for patients who become seriously ill. Currently, there are no established effective drugs to treat the infection before it becomes more advanced (i.e., when patients need oxygen treatment or ventilation). In addition, we do not yet know what the long-term consequences of infection are, even for those who appear to be fully recovered. Global scientific and clinical knowledge of this new virus, including its impact on people, is still evolving.

Therefore, while Health Canada has not received any applications for human challenge trails for SARS-CoV-2 at this time, any future application for authorization by Health Canada would require the human challenge trial to be sufficiently stringent in safety parameters and meet ethical requirements, including access to effective treatments for participants who become ill.

Health Canada regularly collaborates and exchanges information with international regulatory partners such as the US Food and Drug Administration and the European Medicines Agency among others, as well as with public health organizations such as the World Health Organization (WHO).  The WHO has recently published a guidance document relating to human challenge trials for COVID-19.  The principles and considerations included in this response align with those of the WHO.  We will continue to monitor the global situation, and we remain committed to learning from the expertise and experience of our global regulatory and scientific partners with regards to the considerations for the conduct of COVID-19 human challenge trials.