Covid-19 Vaccines in America and How they Work

Updated: May 16, 2021

Audience: Middle School and High School students

By: Nimisa Panda

On December 1, 2019, Patient Zero first exhibited the symptoms of SARS-CoV-2, more commonly known as Covid-19. Over a year later, on December 14, 2020, the first Covid Vaccine was administered. The world has come a long way since then, and the biggest turning point that contributed to this was the creation of the Covid-9 vaccine.

The Covid -19 vaccine is the fastest developed vaccine in the entire history of vaccine development. As of now, there are 3 vaccines that have been approved in America by the Food and Drug Administration (FDA) to be administered, and many more under review. Here is a breakdown of how the Big 3 Vaccines work:

A Newspaper Article from Hawaii spread the news about mass vaccination efforts. Photo provided by Little Plant on Unsplash


Pfizer/BioNTech, more commonly known as Pfizer, is the USA’s first approved vaccine and one of the more popular ones. Pfizer comes in 2 doses, 21 days apart. It has an efficacy of 95% after the second dose, which makes it the most efficient vaccine to date. Pfizer utilizes mRNA molecules that code for a protein to form the Covid-19 molecule. This triggers the body’s fight or flight response to help the immune system create antibodies for the real Covid-19 virus; if the person ever gets the virus, their body can fight off the virus with the antibodies that have already been created. To receive this vaccine, you need to be 16 or older.


Moderna is another popular vaccine. Like Pfizer, moderna comes in 2 doses, but the doses are 28 days apart. Moderna has an efficacy rate of 92% after the first dose, which makes it the most rapid-acting vaccine out of the Big 3 (Pfizer, Moderna, and Janssen/Johnson & Johnson). After the second dose is received, the Moderna vaccine has an efficacy rate of 94.1%. Moderna also uses mRNA to help the body trigger a response from the immune system to create antibodies. To receive this vaccine, you need to be 18 or older.

A Doctor Vaccinates a lucky patient in a drive-by vaccination tent. Photo provided by Alex Mecl on Unsplash

Janssen/Johnson & Johnson:

Janssen, also known as J&J, is the last of the Big 3 vaccines that have been approved in the USA by the FDA. Janssen is vastly different from Moderna and Pfizer. J&J comes in one dose, rather than the typical 2, and the efficacy rate is 85%—much lower than that of the other two. The approach J&J takes to fight the virus is also different: Instead of sending mRNA molecules into the body, the J&J vaccine modifies a preexisting adenovirus in our bodies with the Covid-19 proteins. It is called the viral vectored approach. The adenovirus that already exists in our body travels to a new cell, and this new cell starts to replicate the protein and creates antibodies, which will help the immune system fight off the actual virus. To receive this vaccine, you need to be 18 or older.

In addition to the already approved vaccines, there are many that are in the clinical trial phase of vaccine development.

Some of these vaccines include AstraZeneca vaccines and the Novavax vaccine. At the time of writing, the vaccines are in the large-scale testing phase, known as phase 3.

The situation is rapidly evolving and to keep up with the changes, scientists and medical professionals across the globe are working at warp speed to create vaccines and other protective protocols. The creation of the various approved vaccines and the testing of many others is a whole new ball game for the STEM field as a whole.

As more and more vaccines get approved in hopes to curb the effects of the disease, the world will get a first-hand experience on something truly life-changing.


Allam, Zaheer. “The First 50 Days of COVID-19: A Detailed Chronological Timeline and Extensive Review of Literature Documenting the Pandemic.” Surveying the Covid-19 Pandemic and Its Implications, U.S. National Library of Medicine, 2020,

Commissioner, Office of the. “Janssen COVID-19 Vaccine.” U.S. Food and Drug Administration, FDA,

“Covid-19: First Vaccine given in US as Roll-out Begins.” BBC News, BBC, 14 Dec. 2020,

“Pfizer Vaccine for Coronavirus: Efficacy, Side Effects, and More.” Medical News Today, MediLexicon International,

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