225. Pfizer wanted to switch the “phosphate- buffered saline” used in previous adult formulations, to “tromethamine (Tris) buffer” and to exclude both sodium chloride and potassium chloride, claiming it “improved the stability profile of the vaccine.” A Pfizer spokesperson said, “This allows the mRNA to resist being degraded for a longer period of time before administration – meaning the pediatric vaccine can be stored [at] 2-8°C in commonly available refrigerators for up to 10 weeks.” If the half-life is going to take longer to degrade isn’t that going to increase the pathogenicity of the vaccine for children? 238. Why are there five doses in an adult vial and 10 doses in a children’s vial? Why didn’t the sponsors make it one dose per vial to ensure an even distribution of the vaccine. How can the TGA be sure that the person administering the vaccine is actually giving consistent concentrations?

Question Number: 230
PDR Number: SQ22-000600
Date Submitted: 21/11/2022
Department or Body: Department of Health

Question 225 The Tris buffer improves the stability of the vaccine at refrigeration temperatures. Pfizer has provided data to support and demonstrate the quality of the vaccine is maintained at a temperature that is easier to manage logistically. There is no evidence that the vaccine is pathogenic to either children or to adults. Question 238 Each multidose vial contains the same volume and concentration. The paediatric dose is half the adult dose since children are smaller. Therefore, since each multidose vial contains the same volume and concentration, and the paediatric dose is half the adult dose, the adult vial contains five doses and the paediatric contains 10 doses. The Therapeutic Goods Administration (TGA) independently assesses the quality of every batch of COVID-19 vaccine supplied in Australia and the TGA laboratories carry out a range of tests, including assessments for composition, identity, potency and purity to ensure that the concentration is within approved specifications. 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 the person administering the vaccine is administering consistent concentrations per dose. While some companies have publicly indicated that they are now pursuing single dose vials or pre-filled single dose syringes, in order to effectively achieve mass immunisation programs at a time when global supply chains were heavily constrained during the pandemic, the consensus among global public health professionals was that it was appropriate to pursue multidose vials during the first couple of year of vaccine roll out.