How Do the New Vaccines Work? A Biology Lesson for Grown-Ups

Several COVID-19 vaccines are now available in the United States. These vaccines cause our bodies to produce COVID-19 antibodies, which are natural proteins produced by our immune system to counteract the effect of disease-causing germs. 

The first two vaccines authorized in the United States are made by Pfizer/BioNTech and Moderna; each of these two vaccines involves two shots, spaced about three weeks apart, and each vaccine uses a mechanism that depends on mRNA.

How the Vaccines Work With Your Body

What is mRNA? First, here is a reminder of what DNA is: DNA is a double-stranded material that tells your cells how to look and how to work. RNA is a single-stranded version of DNA with a few differences — and the “m” in mRNA stands for “messenger.” The mRNA is what tells your cells to make various proteins. Both vaccines use mRNA to make the cell produce a harmless piece of the COVID-19 virus, called the spike protein. The spike protein helps the COVID-19 virus enter our cells. This mRNA is the main ingredient in both the Pfizer/BioNTech and Moderna vaccines.

After a patient is injected with the vaccine, the mRNA from the vaccine goes into the cytoplasm, or the filling, of our cells. Note that it does not enter the nucleus, where our DNA instructions are safely stored. After the mRNA makes the piece of the spike protein, the mRNA is broken down by our body and goes away permanently, so our DNA will never be changed by this vaccine. If infected by COVID-19, the COVID-19 virus causes the cell to produce the whole virus, while the vaccine causes a cell to produce only that piece of the spike protein. 

Our immune system has a lot of different kinds of cells, including T-cells and B-cells, which recognize foreign substances and produce antibodies to fight infections. Some of these cells will “remember” the spike protein, which enables the immune system to respond much more quickly and produce antibodies when later exposed to the COVID-19 virus. 

One key note about the vaccines: the first shot only starts to build the protection; the second shot is necessary to get the most protection from COVID-19 available. Even if you have side effects from the first shot, unless your health care provider tells you otherwise, you need the second shot. The vaccine is given in the upper arm muscle.

Ingredients-wise, the Moderna vaccine contains lipids, or fats; salts; sugar; acetic acid; — the acid that makes vinegar taste like vinegar — and an acid stabilizer. The Pfizer vaccine also contains lipids, salts and sugar. The amount of fat, salt, acid and sugar is minimal. Neither vaccine has gluten or eggs.

Pros of Vaccines:

Both vaccines were tested on more than 37,000 people, less than .05% of whom had any serious side effects. Both vaccines are safe and proven to be over 95% effective. The vaccine is safer than getting COVID-19, which is unpredictable and has caused long-term complications and life-threatening complications in many individuals, as well as death in over 400,000 United States residents. With the vaccine, you can get protection from COVID-19 without enduring a full-blown case of the illness. 

Cons of Vaccines: 

There are some possible side effects, which include pain where you are injected, fatigue, headache, low-grade fever and joint pain, usually very mild. A few patients have experienced intense, temporary reactions from either brand of the vaccine, such as feeling like they are coming down with a cold and needing extra rest for a day or so. Even fewer patients have experienced anaphylaxis, a severe allergic reaction. 

The CDC recommends a waiting period of 30 minutes after receiving the vaccine to observe for an allergic reaction. More patients report side effects after the second shot. People are also concerned about the long-term safety effects. However, science has developed many vaccines, and long-term side effects are very rare. The long-term efficacy of the COVID-19 vaccine is not yet proven.  

Every state received an amount of vaccine in proportion to its population; individual states decided which age groups and professions would receive the vaccine first, which has largely been a mixture of individuals aged 65 and older and frontline health care workers.

Scientists and physicians encourage people who have received the vaccine to still maintain social distancing, mask-wearing and hand-washing behaviors. It is unknown if people can still spread COVID-19 even after receiving both shots. The goal is to achieve herd immunity, which is when the number of immune people is large enough that a susceptible person is not likely to run into an infected person. Herd immunity varies, depending on how hard or easy it is to catch a certain disease. Experts say that herd immunity may happen when between 70% to 90% of all United States residents are vaccinated or have been infected. In other words, a minimum of 248 million people need to be vaccinated before herd immunity is achieved. 

Written by: Mariann G. D’Arcangelis

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