Mr. Speaker, the health and safety of Canadians is Health Canada’s top priority, and the department exercises stringent regulatory oversight over vaccines.
Before the initial approval of the Pfizer-BioNTech vaccine, the department completed a rigorous scientific review of the product’s safety, efficacy and quality, including details on manufacturing processes and information on adverse events following immunization. An authorization was only issued once Health Canada confirmed the benefits of the vaccine outweighed the risks of its use. The summary basis of decision can be found at this link: https://covid-vaccine.canada.ca/info/summary-basis-decision-detailTwo.html?linkID=SBD00510.
During the review of the information submitted by the manufacturer, Health Canada became aware of the potential presence of residual DNA in the Pfizer-BioNTech mRNA vaccine preparation. However, the content of the residual DNA was below 10 nanograms/dose. The content of residual DNA was lower than the recommended limits established by the World Health Organization, WHO, in consultation with subject matter experts. Accordingly, the department did not request genotoxicity studies, as the residual DNA was considered a low risk.
Furthermore, the department reviews the manufacturing data for each vaccine lot that is released for use in Canada to ensure they meet their established specifications, including those for residual DNA. The amounts of residual DNA in Pfizer-BioNTech vaccine lots were reported to Health Canada, as well as to our international partner agencies: e.g., EMA and U.S. FDA. Both Health Canada and our international partners consider the test methods used by Pfizer-BioNTech for detecting that residual DNA to be scientifically sound and appropriate for their intended use. As well, the results from the residual DNA tests were consistent among different vaccine lots sold both in Canada and elsewhere and were also consistent with other manufacturing data provided in support of the release of each product lot.
With regard to the Pfizer-BioNTech COVID-19 mRNA vaccine manufacturing process, an SV40 enhancer-promoter region was present in the DNA plasmid template, but has no functional role and is not upstream of any SV40 gene, and the DNA template is digested and filtered to remove from the mRNA vaccine. Health Canada cannot speculate on any intentions by Pfizer-BioNTech in regard to whether they removed the SV40 sequence when reporting the annotated plasmid. Please note that information requested on gene sequences, gene annotation and gene/plasmid map, received on November 16, 2020, as well as analytical techniques used by the manufacturer, are proprietary to Pfizer-BioNTech. However, Health Canada’s scientists reviewed this, and all of the other submitted information, and considered it within the risk assessment for their product. Any residual DNA fragments are considered as inactive, and an internal assessment of submissions by Pfizer-BioNTech found that they were consistently reported below the limit recommended by WHO.
Lastly, the lipid nanoparticle, LNP, component of the Pfizer-BioNTech mRNA vaccine preparation served as a delivery vehicle for the mRNA. Cells cannot efficiently internalize the mRNA in the absence of the LNP.