178. On average how many strands of mRNA are in 30 micrograms of mRNA? Given there are 5 doses in each vial how can the TGA be sure that each dose will contain the same amount of mRNA? 179. What is the margin of error administering 30 uml (.3mL) from a vial with 5 doses? 180. Why didn’t the TGA make Pfzier measure out the 30 microns evenly instead of leaving it to the person who administers the vaccine – the margin of error for such a small dose would be huge would it not? 181. Given the TGA measures mRNA by mass how does it know if they or the administrators of the vaccine are measuring mRNA and not solution?

Question Number: 192
PDR Number: SQ22-000562
Date Submitted: 21/11/2022
Department or Body: Department of Health

Question 178 A single dose of COMIRNATY COVID-19 vaccine containing 30 micrograms of mRNA has approximately 1.30 × 1013 ‘strands’ of mRNA. The Therapeutic Goods Administration (TGA) reviews the ability of the manufacturer to produce consistent batches as part of the evaluation process before approval. After approval, the TGA assesses the quality of every batch of COVID-19 vaccine supplied in Australia, and the TGA Laboratories conduct a range of tests including the amount of mRNA in each batch. For the end user, specific instructions are provided in the Product Information to ensure that the product is diluted, mixed and administered correctly so that doses contain consistent amounts of mRNA.

Question 179 The margin of error for administering the 0.3 mL dose from the multidose vials will depend on multiple factors, such as the types of needles and syringes used at administration, as well as human error. However, as an example when the end user is utilising low dead space needles and syringes, the loss of vaccine/or possible error is the dead space of the needle and syringe, which is up to 0.035 mL (approximately 11.7% of the administered dose). Consistency of dosing is assessed by the TGA as part of the evaluation. However, unlike medicines, small differences in the amount of vaccine administered have very little or no impact on the immune response to and efficacy of the vaccine.

Question 180 The mRNA is not measured out for individual vials. This would be logistically impossible considering the billions of doses and vials produced globally. Commonly accepted scientific practice when dealing with very small amounts of substance is to start with a larger amount that can be accurately measured, ensure thorough mixing in a solution and then dilution to the final desired concentration. The final diluted solution can then be dispensed into the vials. This is much more accurate than attempting to weigh individual doses and is much easier and faster for the end user. The margin of error for the end user is outlined in the answer for Question 179.

Question 181 The TGA Laboratories carry out a range of tests to ensure that the concentration is within the approved specifications as described in the answer for Question 178. The TGA tests through batch release and end user instructions safeguard that the right dose is administered.