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Vaccines help protect the body from disease by teaching the immune system to fight germs.

UNC Health recommends that North Carolina residents receive a COVID-19 vaccine when it becomes available to them. We know some people have questions about COVID-19 vaccines, but also about how vaccines work in general.

How does the body fight illness?

Germs, like bacteria and viruses, enter your body.
Germs multiply in the body.
Body attacks the germs Germs
The body’s immune system is responsible for fighting off infection, helping people feel beter.
Afterwards, the immune system remembers how to fight off that infection, which protects the body from that disease in the future.

How Does A Vaccine Work?

Vaccines can mimic this process and teach the body how to fight the infection, developing immunity in the body, reducing the risk of disease. How the vaccine imitates a viral infection depends on the virus itself. The kind of germ and how it invades and multiplies in the body determine how researchers attempt to create a vaccine to imitate the infection.

Once the imitation infection goes away, the body remembers how to fight an actual infection.

Types of vaccines

There are five types of vaccines that help the body learn to fight infection in different ways.

mRNA Inactive Toxoid Subunit Live
mRNA vaccines: Send instructions to cels to make a protein that triggers an immune response (ex: COVID-19).
Inactivated vaccine: The vaccine contains the germ, but it is killed during manufacturing. These types often offer protection for your lifetime with just one or two doses (ex: polio).
Live vaccines: Contain active, weakened versions of the bacteria or virus (ex: chickenpox).
Subunit, recombinant, polysaccharide, and conjugate vaccines: Contain just parts of the virus or bacteria. These types often need “booster” shots to get ongoing protection (ex: whooping cough).
Toxoid vaccines: Target the harmful part of the germ (toxin that causes the disease) instead of the whole germ.

The future of vaccines

Just as the mRNA vaccine is a new type of vaccine that is built on more than a decade of research, scientists continue to work on creating new types of vaccines. Two examples of new types of vaccines are:

  • DNA vaccines trigger creation of particular molecules that start the immune response.
  • Recombinant vector vaccines, which act like a natural infection

mRNA Vaccines

COVID-19 is caused by a new type of coronavirus, and the first two FDA-authorized vaccines that create immunity to it are called mesenger RNA, or mRNA, vaccines.
Instead of exposing the body to aweakened version of COVID-19, mRNA vaccines send cels a tiny genetic message, or instructions for the body to make a protein that triggers the body to make antibodies.
Antibodies latch onto the coronavirus and mark it for the body to destroy and prevent the virus from infecting other cels.
To make the body most effective to fight coronavirus, the COVID-19 mRNA vaccines are given twice.

While some people experience side effects after getting the vaccine, the COVID-19 mRNA vaccine cannot give someone COVID-19. Side effects are a signal that the body is creating a protective defense against future infection. It does not use a live virus, so unlike some vaccines, even people who are allergic to eggs can get this mRNA vaccine.

  • Learn more about vaccines and vaccine safety from the CDC here.
  • Learn more about how the Pfizer-BioNTech COVID-19 vaccine works.
  • Learn more about how the Moderna COVID-19 vaccine works.



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