Supercooling experiments were carried out covering a total of about 300 vials. The vials were either directly exposed to cold air or positioned in boxes in a cold storage room. It was found that vials containing the COVID vaccine with thermocouples located on the external side of the vial body would nucleate mostly in a temperature range of -15°C to -10°C; vials with thermocouples inside the vial were found to nucleate at temperatures anywhere from -15°C to the equilibrium freezing temperature. Since the thermal evolution of these vials was not tightly controlled, an estimation of the nucleation kinetics based on these data alone is not possible. However, these experiments indicate that a metastable zone for the COVID-19 vaccine extends down to at least -10°C. Engineering run material comprising the drug product at a concentration similar to that of the final formulation was filled in ISO 2R vials. The vials were packed together according to the aforementioned pallet configuration. A weight check was conducted to ensure homogeneity of fill volumes. The cooling process itself was initiated by moving the packed pallet into a cold storage room after filling; the pallets were positioned in the warmest part of the cold storage room to allow for a worst-case estimate of the process duration.