Comparison of Vaccine Freezing Methods

No access to the full paper due to lack of a FERPA release.We have developed a temperature-sensitive vaccine formulation in a glass vial that needs to be frozen prior to lyophilization.The method for freezing the vial has traditionally been liquid nitrogen tunnel freezing, but this method can be expensive and has problems with sterilization of the tunnel.We explored the advantages of a shelf-freezing method and did a comparison analysis on the two freezing methods to determine which situation was the preferred one.For our analysis, the vaccine vial dimensions were obtained from research performed by Merck & Co., Inc.We predicted that the shelf-freezing method would take too long to freeze the vaccine, which in turn would decrease the potency of the vaccine.We simulated both freezing methods using the Gambit and FIDAP programs to produce two different designs.For the sensitivity analysis, we manipulated the boundary temperatures of the shelf and the liquid nitrogen as well as the convective coefficient for the ambient air in the shelf design.We determined that the shelf freezing method was the most optimal for the freezing of the vial when we lowered the shelf temperature due to the small differences in the freezing times between the two methods