What Have You Heard About Herd Immunity and COVID-19?

What Have You Heard About Herd Immunity and COVID-19?

This article is for anyone who wants to learn more about COVID-19. The goal of this patient education activity is to help patients and their care partners talk to their doctor about COVID-19 vaccines and engage in shared decision-making.

You will learn about:

  • How your immune system and vaccines help protect you

  • COVID-19 vaccines

  • What herd immunity is

  • Why reaching herd immunity is important

  • Questions to ask your doctor

Medicines listed in this activity have either a US Food and Drug Administration (FDA) approval or have been given an Emergency Use Authorization (EUA) by the FDA to treat or prevent COVID-19.

The information on COVID-19 is continually changing. The content in this activity is accurate based on the information that was available at the time of its publication. This resource is provided for educational and informational purposes only. We do not provide medical advice, diagnosis, or treatment.

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How Your Immune System Protects You

Your immune system is your body's natural defense system. It's made up of different organs, cells, and proteins that work together to protect you when you're exposed to outside invaders, such as bacteria and viruses. This includes the coronavirus (a type of virus) that causes COVID-19.

When you're exposed, your immune system is triggered and activates certain cells and proteins to fight off infection. This includes a special type of white blood cell called B cells. B cells make proteins called antibodies that are released into your bloodstream to attack the invader and fight off infection.

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How Antibodies Go to Work Against a Virus

Viruses don't have everything they need to replicate, or make more viruses, once inside your body. To do so, they have to attach to and enter, or infect, a healthy cell.

Antibodies are specialized, Y-shaped proteins that can fit on a virus like a lock and key. Once antibodies are released into your bloodstream, they can find a virus and bind to it to stop it from infecting healthy cells.

It can take several days or weeks for antibodies to develop. But they stay in your body and can recognize and defend against the virus if you're exposed to it again later. This is how you can develop protection -- or immunity -- against that virus.

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Vaccines and Your Immune System Work Together

Vaccines have been used for hundreds of years to help protect us against many different diseases. Unlike medicines given after an infection to treat disease, vaccines are given before an infection to try to prevent disease.

Once given, a vaccine triggers your immune system to make antibodies to a specific outside invader. Once antibodies develop, you have immunity against a future infection from that invader without having to actually get the disease first.

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COVID-19 Vaccines

COVID-19 vaccines help you build immunity by triggering your immune system to make antibodies to the virus that causes COVID-19. It's important to know that you can't get COVID-19 from the vaccine because it doesn't contain the live virus.

The COVID-19 vaccines currently being used in the United States have an Emergency Use Authorization (EUA) from the FDA. A vaccine may get an EUA when the FDA has found that the known and potential benefits of using the vaccine outweigh the known and potential risks.

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What Is Herd Immunity?

Herd immunity -- sometimes called community immunity -- happens when a large part of a group of people becomes immune to a specific disease, making the spread of that disease unlikely.

If enough people become immune, it's much harder for a disease to spread from person to person. So with herd immunity, the entire community is protected from getting the disease, even people who are not yet immune themselves.

Reaching herd immunity is important because if a disease can't spread, infection rates drop and the disease fades out.

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Before herd immunity (top row), uninfected people in blue have a greater chance of becoming infected in red. With herd immunity (bottom row), having people who are immune in yellow protects the group and results in fewer infected people.

Whom Does Herd Immunity Protect?

Herd immunity protects everyone. But it is especially important to reach herd immunity to protect people who are at a higher risk for severe illness.

For COVID-19, this includes elderly people, pregnant women, and people with certain medical conditions, such as diabetes, obesity, high blood pressure, cancer, certain lung conditions, and a weakened immune system. This is not a complete list of conditions. Talk to your doctor about whether you could be at a higher risk of severe illness from COVID-19.

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How Do We Reach Herd Immunity?

Herd immunity is reached 2 ways. It usually happens when enough people in the group or community get a vaccine. But it can also happen when people get infected with the disease and build immunity that way.

Chickenpox, polio, measles, and mumps are examples of diseases that used to be very common, but are now rare in the United States because vaccines helped us reach herd immunity.

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Reaching Herd Immunity Is Important

Reaching herd immunity is important in order to keep everyone safe and healthy. It can also help control the COVID-19 pandemic. Getting the COVID-19 vaccine helps protect individuals and the community.

And because COVID-19 can cause long-term damage and be life-threatening, getting the vaccine is a safer way to help build immunity than getting the disease. If you get COVID-19, you run the risk of severe illness and the damage that COVID-19 can do to your body.

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Dr Ragan Johnson, nurse and professor, talks about why reaching herd immunity for COVID-19 is important.

Questions to Ask Your Doctor

Questions you can ask your doctor about building immunity to COVID-19 and the vaccine can include:

  • How can I build immunity to COVID-19?

  • What is herd immunity and why is it important?

  • What vaccines are available for COVID-19?

  • Where can I get a vaccine?

  • If I've had COVID-19, should I still get a vaccine?

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You have successfully completed the program What Have You Heard About Herd Immunity and COVID-19?

View Additional Materials on this topic that you may find useful:

Patient Handout

FAQs About COVID-19 Vaccination

Benefits of Getting a COVID-19 Vaccine

Key Things to Know About COVID-19 Vaccines

Myths and Facts About COVID-19 Vaccines

Different COVID-19 Vaccines


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Authors and Disclosures


Ragan Johnson, DNP, FNP-BC, CNE

Assistant Clinical ProfessorDuke University School of Nursing.

Disclosure: Ragan Johnson, DNP, FNP-BC, CNE, has disclosed no relevant financial relationships.

Clinician Reviewer

Susan L. Smith, MN, PhD

Senior Director, Learning & Development, Medscape, LLC.

Disclosure: Susan L. Smith, MN, PhD, has disclosed no relevant financial relationships.


Anita A. Galdieri, PharmD, RPh

Associate Medical Education Director, Medscape, LLC.

Disclosure: Anita A. Galdieri, PharmD, RPh, has disclosed no relevant financial relationships


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