Understanding the COVID Vaccine: How mRNA Immunizations Work

Are you vaccinated? That is the question on minds all across the nation. The latest figures show that the majority of U.S. adults have received at least one dose of a COVID-19 vaccine. If Americans continue to be immunized at a steady pace, the nation should be on track to meet President Joe Biden's goal of having 70 percent of the adult population receive at least one shot by July 4th.

 

Three COVID vaccines—Pfizer BioNtech, Moderna, and Johnson & Johnson/Janssen—are available to adults. Recently, Pfizer also opened up its shot to children over age 12. If you have not received your first dose, you may want to learn more about the safety and efficacy of the vaccine or understand how this immunization works differently than others have in the past.

 

Neil Minikes, MD, an allergy and immunology specialist at Summit Health, explains how an mRNA vaccine protects you, why the shots are both safe and effective, and what life may look like once you are fully immunized.

 

How does the COVID-19 virus infect human cells?

The COVID-19 virus is typically absorbed into the body through membranes like the lungs, nose, mouth, and eyes. The virus then infects human cells, where it multiplies and causes disease. The protein that enables the virus to enter human cells is called the “spike protein.”

 

In general, how do vaccines work?

The goal of all vaccines is to stimulate the body’s immune system to make antibodies against infectious organisms. Antibodies are immune proteins that “recognize” the germ, attach to it when it enters the body, and then lead to its destruction. Vaccines have different ways of achieving the goal of antibody production.

 

I keep hearing that the Pfizer and Moderna COVID-19 shots are mRNA vaccines. What does that mean? How does mRNA immunization work?

Think of a human cell as a protein factory. Our DNA inside our cells sends messages to the protein producing structures in the form of mRNA, or messenger RNA. In the case of mRNA vaccines, mRNA teaches our cells how to make the spike protein, the part of the COVID-19 virus which enables it to enter human cells. When your body produces this spike protein, the body’s immune system recognizes it as a foreign particle and generates antibodies. In the future if the COVID-19 virus enters the body your antibodies will recognize and destroy the virus.

 

Does the vaccine have an effect on my genetic material?

Absolutely not. mRNA in the vaccine only lasts a short time in the body before it is degraded. It does not enter the cell nucleus where your DNA is located and cannot change a person’s genetic material in any way. It stays in the cellular factory and is disintegrated shortly after it instructs the cells to make the spike protein. No genetic material from the vaccine remains in the body long term and cannot have any effect on the body’s genetics.

 

How does the vaccine protect me from COVID-19 infection?

Once your body has made any antibodies they circulate around the body looking for foreign invaders. When a person is immunized, they will have high levels of anti-spike protein antibodies ready to fight the virus. If that individual is then exposed to the COVID-19 virus, the antibodies immediately bind to the spike protein and prevent the virus from entering human cells.

 

How is an mRNA vaccine different from other types of vaccines?

Vaccines work in many different ways to imitate a real infection so the immune system can recognize a true infection in the future. Some vaccines are made up of the whole virus or a part of the virus to activate the immune system (e.g. inactivated vaccines, live attenuated vaccines). Other vaccines use a benign version of the toxin released by bacteria or other pathogens (toxoid vaccines). And some vaccines employ a piece of genetic material to help the body make a protein that mimics the infection (mRNA vaccines). Remember, the vaccine will not cause an infection.

 

- In the case of inactivated vaccines, the infectious agent, typically a virus like influenza, is “broken down” into viral particles that are unable to cause disease. These viral particles are then injected into an individual and recognized by the immune system as foreign, resulting in the production of antibodies.

 

- Live attenuated vaccines, such as MMR and varicella (chickenpox), have a similar mechanism of action. In this case, the virus is treated in the lab to make it much less infectious. These vaccines cause the immune system to mount a strong antibody response. In both of these situations, the end result is to produce high levels of protective antibodies against the infectious agent.

 

- In Subunit/conjugate vaccines a specific part of the pathogen is injected into the body to train the immune system to fight an infection from the pathogen.

 

- Toxoid vaccines are produced from modifying the toxins made by bacteria. When the immune system recognizes the toxoid, it learns how to fight off the natural toxin in the future.

 

- The mRNA vaccine does not contain the COVID-19 virus. Instead, the mRNA vaccine causes the production of the spike protein. This results in the production of antibodies that block the spike protein and thereby block the COVID-19 virus from entering the human cell. When the virus subsequently enters the body, the antibodies attach to the virus, prevent infection, and lead to its destruction.

 

What is the benefit of an mRNA vaccine?

The major benefits of the mRNA vaccines are their excellent track records for efficacy and safety.

 

Effectiveness: The Pfizer vaccine has been shown to be 95 percent effective in preventing symptomatic COVID-19 infection one week after the second dose, while the Moderna vaccine was shown to be 94 percent effective after 14 days following the second dose. These efficacy rates are as good as any vaccine ever developed. In addition to preventing infection, the vaccines are highly effective in preventing hospitalization.

 

Safety: Local and systemic reactions, including pain and swelling in the arm of the injection, fever, chills, headache, and fatigue, are common. These side effects, which range from mild to moderate, may last for up to two days. However, more severe allergic reactions, or anaphylaxis,

 

are very rare— No other major safety risks have been identified with the mRNA vaccine even after more than 150 million doses.

 

Is mRNA a new technology? 

No, mRNA vaccines are not new and yes, they have been studied since the 90s. They have been researched in other viruses such as Zika, cytomegalovirus (CMV), and rabies. The COVID-19 vaccines are the first mRNA vaccines to be tested and used in humans.

 

I am fully vaccinated, now what?

According to the Centers for Disease Control & Prevention, you can resume activities that you did prior to the pandemic. Mask wearing is not needed except where required—such as in health care facilities. And you do not need to keep a social distance of six feet. You do not need to be tested prior to traveling within the U.S. but should check the requirements of any international destinations. When you come back to the U.S., you will need to document a negative test for COVID-19. You are not required to quarantine after international travel, but you should get tested within 3 to 5 days after returning.

 

How does getting vaccinated help others?

When a majority of the population is vaccinated the virus cannot spread in the community.  This way you help protect those who may not be eligible to the vaccine or those who may not mount a strong immune response despite being vaccinated.