Good Practices of Comirnaty® Vaccine Injection Using Uncrimped Materials

Background: In 2020, the first mRNA COVID vaccine was approved by the with six doses from single vial. In the context of material shortages, the aim of the study was to compare different protocols to extract doses using uncrimped materials with good trueness and reproducibility. Methods To optimize the extraction of the sixth dose from a single vial with uncrimped materials, alternative protocols of preparation were tested, derived from the drug information. Results The repeatability of injected volume was acceptable for all protocols (CV<5.3%). To prepare six 0.3mL doses using uncrimped materials, protocols with an air bubble were evaluated to offset the high dead volume inherent to uncrimped materials. Regarding the limited doses observed using long intramuscular needle (92.8% of the reference dose), the air bubble protocol with a liquid volume adjustment at 0.27mL was finally validated to respect the administration of full doses. Conclusion Results highlighted the necessity to adapt the drug information protocol for the preparation and administration of Cominarty®, due to the use of high dead volume materials. Despite the good reproducibility and accuracy of the air bubble protocols, some precautions have therefore to be taken to maintain the integrity of the vaccine suspension for efficient administration.