Herd Immunity Animation

Herd Immunity
START
NEXT
Screen 1 of 7
Did you know that vaccination not only protects you from disease but can also help protect people in your community who are not vaccinated. This phenomenon is known as 'herd immunity.' We'll explain what all these red and blue circles mean. Just click 'Next' to see a simple demonstration of how herd immunity works ... and how it can fail.
Previous
Replay
In this demonstration, light blue circles represent healthy people who are not vaccinated. In pictures to come, dark blue circles will represent healthy people who get vaccinated, and red circles will be the people who become sick.
Sick
How disease spreads
Unvaccinated
Screen 2 of 7
Vaccinated
Screen 3 of 7
How vaccination protects a community
Vaccination protects against disease by stimulating the immune response against a specific germ. In this case, most of the people in one area -- the gray area in the center -- chose to be vaccinated. They're the dark blue circles. None of the other people outside the gray area got vaccinated: they're all light blue. The people in the gray area make up the herd community."
Screen 4 of 7
Screen 5 of 7
As the infection spreads, the unvaccinated people in the herd community -- the community where a lot of people got vaccinated -- escape the infection because they are protected by the vaccinated people who surround them. But the people outside the herd community where no one got vaccinated, all get sick.
Herd immunity works only to a point. In this situation, too few people in the herd community have been vaccinated to create the herd immunity effect.
When herd immunity fails
Screen 6 of 7
When disease strikes this time, those people in the gray area who are vaccinated are protected but there are not enough of them to protect people who are not vaccinated -- most of them get infected. Herd immunity has failed to occur.
Screen 7 of 7
Share
Print This Page

Disclaimer:

As a service to our readers, Harvard Health Publishing provides access to our library of archived content. Please note the date of last review or update on all articles.

No content on this site, regardless of date, should ever be used as a substitute for direct medical advice from your doctor or other qualified clinician.

Recent Articles
blog image 1

Stopping a medication?
blog image 1

Time for a medication check-up?
blog image 1

Risk factors for MCI and dementia
blog image 1

Handling tough decisions as a caregiver
blog image 1

How we make memories
blog image 1

Treating mild cognitive impairment
blog image 1

How high blood pressure harms your health
blog image 1

How to fall without injury
blog image 1

Cholesterol's various forms
blog image 1

Are you at risk for high blood pressure?
/

Free Healthbeat Signup

Get the latest in health news delivered to your inbox!

Sign Up
Harvard Health Publishing Logo

Thanks for visiting. Don't miss your FREE gift.

25 Gut Health Hacks is yours absolutely FREE when you sign up to receive health information from Harvard Medical School.

Sign up to get tips for living a healthy lifestyle, with ways to lessen digestion problems…keep inflammation under control…learn simple exercises to improve your balance…understand your options for cataract treatment…all delivered to your email box FREE.

Harvard Health Publishing Logo

Stay on top of latest health news from Harvard Medical School.

Plus get a FREE on-line course Inflammation and Diet: How food can lower disease risk. No purchase necessary.

Harvard Health Publishing Logo

Stay on top of latest health news from Harvard Medical School.

Plus get a FREE on-line course Inflammation and Diet: How food can lower disease risk. No purchase necessary.