# Explorative Supercooling Technology for Prevention of Freeze Damages in Vaccines
## 4 Conclusions  
The OMF-based supercooling innovation has no detrimental impact on physical characteristics of freeze-sensitive vaccines, even when they are stored at temperatures below freezing point. Therefore, this technology can also eliminate the likely human error associated with varying instances of freeze damage in vaccines. Indeed, guidelines set forth by WHO are unfollowed and have shown to be ineffective in preventing temperature abuse among vaccine distributors and dispensers [3]. It can be envisioned that the supercooling technology becomes an integral feature in the \"cold chain\", regardless of storage specifications and temperature-related needs for different vaccines.  
As long as a power supply is available at every part of vaccine distribution, workers would simply place the vaccines in a storage container with supercooling technology. Maintenance of supercooling units would be minimal, and careful storage of vaccine products with ice packs would not be needed. Furthermore, separating diluent and pellets would no longer be necessary for such aluminum adjuvant vaccines as the _Haemophilus influenzae_ type b (Hib) vaccine, as reconstituted vaccines could be stored without much worry for accidentally freezing the diluent liquid or damaging the vaccine itself [24].  
Perhaps the developed supercooling technology, further assisted by bioinformatics, could provide an umbrella option where no concern for the various types of storage and temperature specifics (thermal shipping, ultracold storage, and refrigeration upon thawing)  
Figure 6: Temperature profiles of study vaccines after 7 days of storage: (**a**) supercooled (\(-14\)\({}^{\circ}\)C) and (**b**) frozen (\(-14\)\({}^{\circ}\)C). Inserts show snapshots of supercooled and control vaccines after shake tests.  
is necessary. In this sense, supercooling would act as a subzero storage situation for these vaccines without the drawbacks of freezing the vaccines and eventual thawing.  
Future work will definitely include the enzyme-linked immunosorbent assay (ELISA) and immunogenicity tests based on animal models to validate the supercooling preservation. Thereafter, commercially viable units can be designed in consideration of the most optimal magnetic field strength, uniformity, and application frequency specifications for various vaccines--not only aluminum adjuvant types--and then designing for macroscale, larger-capacity supercooling chambers. Electromagnet design types (ferric-core-material-based, Helm-Holtz-based, etc.) and their limitations will heavily depend on the chamber's established specifications, with practical limitations set upon the weight, design, shape, and volume of said chamber. Despite its novelty and need for in vivo validation of immunogenicity, the supercooled vaccine storage can potentially be a promoter of increased vaccine distribution and usage in this field.  
In addition, cryopreservation has been successful in numerous cell types and some simple tissues. However, conventional approaches to cryopreservation cannot be applied to more complex natural or engineered multicellular tissues due to the destructive effect of extracellular ice formation. Restricting the size and extent of ice crystal formation during cryopreservation was marginally achieved using sufficiently high concentrations of cryoprotectants to promote amorphous solidification (vitrification) rather than crystallization. The supercooling technology is expected to be an alternative to cryopreservation technology for mammalian cells, organs, and tissues by lessening the toxicity issue of cryoprotectants and simplifying the procedure.  
Writing--original draft preparation, S.J.; investigation, S.J.; writing--review and editing, Y.K. and S.H.L.; project administration, S.H.L. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
Data Availability Statement: Data presented in this study are available in the article.  
The authors declare no conflict of interest.