Why Do Covid-19 Vaccines Need to be Kept So Cold?

 

 

   As I am sure most of you have heard, Pfizer has produced a vaccine for Covid-19 and is awaiting approval from the U.S. Food and Drug Administration. However, unlike most other vaccines, their product must be stored at -70 degrees Celsius. The vaccine is based on messenger RNA, "which carries instructions for building copies of coronavirus' spike protein. Human cells read those instructions and produce copies of the protein, which in turn, prime the immune system to attack the coronavirus," (Saey, 2020). But, why does this vaccine need to be kept so cold? The main reason is in the chemical differences between RNA and DNA. RNA is used in cells to create proteins, but after the mRNA is read, is it degraded, which helps in controlling the amount of protein made. By putting RNA-based vaccines in the freezer, this prevents the enzymes from destroying the RNA, which is needed in a vaccine. Another difference between DNA and RNA is in their nucleotide bases. DNA has thymine, while RNA has uracil. The nucleotide uracil juts out from the RNA strand and causes some issues when dealing with vaccines. Uracil acts as a flag for special proteins in the immune system that are involved in detection of viruses. Lastly, RNA's single strand structure creates many secondary structures in the RNA strand, which makes RNA quite unstable. All of these obstacles in RNA make it difficult for vaccine makers to create a vaccine that allows RNA to survive at least long enough to make proteins. Storing the vaccine in extremely cold conditions aids in these RNA-based problems, but still does not solve all of the problems faced by vaccine makers. In my opinion, it is going to be nearly impossible to get vaccines to the general public with such stipulations. Unfortunately, our freezers at home don't reach -70 degrees Celsius, so storage is the biggest issue these companies face. Maybe a better way to adjust the vaccine would be to provide storage containers that allowed the vaccine to be used up to a certain amount of days. Similar to how a thermos keeps beverages hot or cold, maybe the vaccine could be placed in a device that keeps the vaccine cold until use. This may be easier than trying to reconfigure the chemical nature of the vaccine, however, vaccine makers will need more time to fix these problems before the vaccine can be distributed. 

https://www.sciencenews.org/article/coronavirus-covid-19-why-vaccines-cold-freeze-pfizer-moderna

https://www.npr.org/sections/health-shots/2020/11/17/935563377/why-does-pfizers-covid-19-vaccine-need-to-be-kept-colder-than-antarctica