Vaccines 2.0: The Science Behind the Pfizer Vaccine

By Diya Ramesh (’23)

Just when you thought you were ready to understand the turbulent, dynamic world of vaccines, a bombshell hits (a good one though). You just got home and are about to turn on Netflix, when a wave of deja vu washes over you, and you flip to the news instead. Lo and behold, the news is talking about vaccines. The original may have been thrilling, but the sequel packs a real punch. Every channel you turn to is talking about Pfizer’s vaccine. You’re confused on what it is, but you’re also intrigued and ready to find out.

Pfizer is a multinational pharmaceutical company from the United States. Recently, along with their German partner, BioNTech, Pfizer gave a press release stating that the initial results of their vaccine had over 90% efficacy. These results came from the beginning of data from a phase 3 clinical trial. However, this still leaves us wondering, what does this vaccine do?

Well, as we previously learned, our body’s immune system is used to fight off various invaders. The innate immune system is our body’s immediate response to such invaders, but it is our adaptive immune system that has “memory”. When we are exposed to pathogens, our adaptive immune system eventually produces specific antibodies to the pathogen that can be used in the future against the same pathogen. In other words, this adaptive immune system is what truly allows the body to become immune to a disease. So, vaccines harness the amazing power of the adaptive immune system, by giving our body some exposure to specific antigens (something that causes an immune response), thereby forcing our immune system to produce these antibodies and gain immunity, without actually contracting the illness. There are various types of vaccines, in which the antigens are in a condition that they could not cause any serious damage (ex: a weakened antigen or a dead antigen). So, where does Pfizer’s vaccine fit into all this?

The Pfizer vaccine is an mRNA vaccine. As you may have learned in your biology class, mRNA, which stands for messenger RNA, is part of the central dogma (the process through which DNA is used to make proteins which serve various functions in the body). Our DNA is transcribed into mRNA, which is then translated into proteins. With mRNA vaccines, such as the Pfizer vaccine, the mRNA that is provided through the vaccine is from the virus and utilizes the body’s existing systems to create the proteins that the viral mRNA encodes for. For the Pfizer vaccine, the mRNA produces the spike proteins that are on the outside of SARS-CoV-2 (the virus that causes the disease, COVID-19). So, when this mRNA is transcribed into the spike protein, it triggers the immune system, as the spike protein is foreign to the body. The actual virus never even enters the body, so there is no chance to become ill. These types of mRNA vaccines are comparatively newer, but it is possible that they will be safer and provide higher efficacy than other vaccines.

Actually distributing the vaccine is another challenge that may take some time, but overall, what we have right now seems to have potential. Pfizer has so far not found any safety issues, and if the 90% efficacy is for certain, this is truly better than expected. However, much work still remains to ensure that the vaccine works for sure. So, the next time you turn on the TV, say thanks to the central dogma and the fabulous power of your adaptive immune system.

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