Viking Call

Upper Merion High's Student Newspaper


Pfizer/BioNTech and Moderna Vaccines: What’s the Difference?

COVID-19 has taken away friends and family from many Americans, and it’s beginning to seem like the quarantine will never end. That would be the case if, of course, we didn’t have science and modern medicine. There’s 2 vaccines available for the US now, but what’s the difference. Let’s dive right in.

In terms of effectiveness, both vaccines have shown similar results in trials over short time frames. The difference between the long term efficacy is currently unknown, as both clinical trials have been massively accelerated. 

Both vaccines require 2 doses, about a month between the first and second doses, the Pfizer vaccine having a slightly shorter wait at 21 days compared to Moderna’s 28 days. Unfortunately for much of the student population, the Moderna vaccine is only for patients aged 18 and greater. The Pfizer vaccine, however, can be used on patients aged 16 and up. 

Storage of vaccines is important for their use, and unfortunately both vaccines have quite demanding requirements. Moderna’s must be shipped at -4 Fahrenheit; Pfizer’s must be shipped and stored at -94 Fahrenheit. -4 Fahrenheit is about the temperature of an average freezer, whereas -94 Fahrenheit is the temperature of a special ultracold freezer. These special freezers are expensive, and make usage of Pfizer’s vaccine impractical in areas without highly advanced medical facilities with the proper storage. After thawing, the Pfizer vaccine is also unstable and must be used within 5 days, whereas the Moderna vaccine has a shelf life of 30 days. 

What makes their storage so complicated? Both vaccines have a very fragile active ingredient, mRNA. The mRNA is encoded with the coronavirus’ proteins. This means that when administered, the mRNA will cause the production of coronavirus proteins which the immune system can recognize. To transmit the data, mRNA is a long chain of different nitrogen bases (nucleotides) that match to certain sequences of amino acids. This makes it chemically active, so that it may participate in the creation of these sequences. Unfortunately, this also makes it unstable, and will break down relatively quickly. 

The difference between the vaccines as of now is probably not significant, because of the current supply. If someone is vaccinated, it’s probably what was immediately available, rather than what they chose. For the student population, it’s likely that nobody will be vaccinated for a while. Regardless, we should all follow hygienic practices, socially distance, and wearing masks. Our time has come to push back against the virus, and each of us should do the best we can to stop the spread. Stay healthy!


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