Question Number: 144
PDR Number: SQ22-000144
Date Submitted: 24/02/2022
Department or Body: Department of Health
Question 98
The potential for carcinogenicity was not studied which is consistent with the World Health Organization (WHO) guidelines for the nonclinical evaluation of vaccines Available at: www.who.int/biologicals/publications/trs/areas/vaccines/nonclinical_evaluation/ANNEX%201Nonclinical.P31-63.pdf. Similarly, overseas regulators have not required these studies.
This is also because mRNA vaccines are highly unlikely to be carcinogenic for the following reasons:
- The mRNA encoding the spike protein is highly unlikely to be carcinogenic given that the presence of vaccine mRNA in the cell is transient, not permanent, and that the vaccine mRNA is non-replicating. It is quickly metabolised and eliminated via normal cellular processing mechanisms. The antigen protein undergoes proteolysis as for endogenous proteins.
- Lipid excipients as part of the lipid nanoparticles in the vaccine are not genotoxic, i.e. they do not cause genetic damage, based on studies with structurally very similar lipids. In addition, the human dose of the lipids in the vaccine is below the threshold of toxicological concern for genotoxicity and carcinogenicity based on the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use. Therefore, the lipid excipients in the vaccine are not expected to be genotoxic or carcinogenic based on the low exposure, duration of exposure and absence of structure alerts for mutagenicity.
Question 99
Response previously provided in:
- SQ21-001264 – Testing on pregnant women and the safety of vaccines (answer date: 28 January 2022, Q125).
- SQ21-001176 – COVID vaccine approval process (answer date: 31 January 2022, Q119). Please also refer to response to Question 50 provided in SQ22-000114.
Questions 100 & 101
While the decision to provisionally approve COVID-19 vaccines was made on the basis of short-term safety and efficacy data, and considerations of the seriousness of COVID-19, the data submitted to support the quality, safety and efficacy of the COVID-19 vaccines showed a positive benefit-risk ratio. Waiting for data to establish the duration of protection would not have allowed these vaccines to have been available in the necessary timeframes. The efficacy of these vaccines has been proven preventing many hospitalisations and deaths.
The pivotal Pfizer trial was a large, randomised, placebo-controlled trial, which followed subjects for a median of two months post Dose 2. The submitted safety data fulfilled the requirement set out in the Access Consortium statement on COVID-19 vaccines evidence, which states that participants must be followed for a median of at least two months after receiving their final vaccine dose. Available at: www.tga.gov.au/access-consortium-statement-covid-19-vaccines-evidence.
The pivotal trials for each of the provisionally approved COVID-19 vaccines were conducted with placebo or active controls to determine comparative efficacy and safety in subjects who did not have prior evidence of SARS-CoV-2 infection. The placebo group was not vaccinated. During a pandemic, to have not disclosed to the tens of thousands of individuals that they have had a placebo rather than vaccine, and thus should be vaccinated if they so choose, would also have been unethical.
The Therapeutic Goods Administration (TGA) also has enhanced its monitoring procedures in place to detect and investigate signals for potential safety concerns with COVID-19 vaccines. If the TGA detects a safety concern, rapid action will be taken to address the safety issue and promptly provide information to the public.
Post-market surveillance data on global real-world use of COVID-19 vaccines continue to provide reassurance about their longer-term safety. This is supported by reviews of safety data by international medicines regulators in countries with extensive COVID-19 vaccine experience.
