Skip to main content
State of Wisconsin flag

Official website of the State of Wisconsin

Dot gov

Official websites use .gov
A .gov website belongs to an official government organization in the United States.


Secure .gov websites use HTTPS
A lock () or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

We have refreshed our website: Tell us what you think

Use the "Site Feedback" link found at the bottom of every webpage. We look forward to hearing from you!

COVID-19: Immunity

Immunity is your body's ability to protect you from getting sick. If you are immune to a disease, it means you are less likely to get sick and more likely to stay healthy if you are exposed to a germ or virus that causes disease. Vaccines are one of the most important scientific discoveries in history because they help people develop immunity and stay protected against deadly disease. By vaccinating enough people, doctors and scientists have been able to eliminate disease like smallpox and polio and save countless lives!

You build immunity to a disease when your body makes antibodies. Antibodies are made by your body after you are exposed to a virus or germ that might make you sick. Antibodies can also be made after you receive a vaccine that causes an immune response. Vaccines are usually the safer way to build immunity because you don't have to get sick to begin to develop immunity. Antibodies "remember" viruses and germs and can detect them if you are exposed to them again. This helps your body quickly fight off disease to stay healthy. 

Types of immunity

There are two main types of immunity that provide protection against diseases:

  • Active immunity happens when you are exposed to something that causes your immune system to develop antibodies.
  • Passive immunity happens when you are directly given antibodies and your body does not have to work to develop them.

How do you build immunity against COVID-19?

COVID-19 vaccines are the safest way to build immunity because they cause a predictable and strong immune response. Getting a COVID-19 vaccine gives people a high level of protection against COVID-19 and can provide added protection for people who already had COVID-19. People who have not been vaccinated are more likely to be hospitalized and die due to COVID-19.

  • When you get vaccinated against COVID-19, the vaccine teaches your immune system how to fight off the virus, which includes making antibodies, without the risks that come with being infected.
  • Scientists have confirmed that COVID-19 vaccines are safe and effective
  • Getting vaccinated against COVID-19 is a form of active immunity.

  • After someone recovers from COVID-19, they develop antibodies that can provide protection against COVID-19 if they are exposed again.
  • If you do not get vaccinated and only rely on this type of immunity, you are more susceptible to getting sick again or experiencing severe disease if there is a new variant.
  • Getting sick with COVID-19 is a form of active immunity.

  • If a pregnant person has developed antibodies from the COVID-19 vaccine or from getting sick, they may pass protective antibodies to their baby before they are born. However, pregnant people (and people who were recently pregnant) are more likely to get severely sick from COVID-19 compared to people who are not pregnant. Additionally, if you have COVID-19 during pregnancy, you have an increased risk for complications that can affect your pregnancy and developing baby. Vaccines are the safest and most predictable way to develop immunity against COVID-19, especially for people who are pregnant.
  • If a person with antibodies breastfeeds their child, they may pass some antibodies to their baby through breast milk, providing them protection.
  • This is a form of passive immunity. Passive immunity is not long lasting so everyone should get vaccinated against COVID-19 when eligible.

  • COVID-19 monoclonal antibody treatments can provide protecting antibodies that strengthen your immune response and give short-term protection against COVID-19. However, COVID-19 monoclonal antibodies do not provide long-term protection against COVID-19.
  • Evusheld™ is the only long-acting monoclonal antibody therapy that can be taken before you are sick with COVID-19 to help prevent severe disease.
  • Everyone who is eligible should get vaccinated against COVID-19 for the safest form of protection.
  • Getting COVID-19 monoclonal antibodies is a form of passive immunity.

Population immunity is key

Population immunity occurs when enough people have developed some form of immunity to a specific disease. When enough people have developed immunity, it slows the spread of disease and provides protection for those who are not yet immune. High levels of population immunity against COVID-19 have contributed to the overall decline in the number of new cases and hospitalizations across the United States. However, some COVID-19 variants may be able to dodge immune systems. Staying up to date on COVID-19 vaccines provides additional protection and helps prevent new variants from forming.

I have already gotten sick and recovered from COVID-19, why should I get the vaccine?

People who are vaccinated typically have a higher initial immune response and a longer immune memory than unvaccinated people who have recovered from COVID-19. It was found that among people who already had COVID-19, those who were not vaccinated were two timesas likely to get COVID-19 again compared to those who were fully vaccinated after their recovery. Beyond protecting yourself, getting vaccinated also protects people around you who may be more vulnerable to severe disease. When you are less likely to get COVID-19, you are less likely to spread the virus to your friends and family, too!

Can the amount of immunity I have decrease over time?

The amount of protection gained from COVID-19 vaccines and from getting sick with COVID-19 may vary from person to person and decrease over time. However, booster doses can help protect you from getting COVID-19. This is why staying up to date with your COVID-19 vaccines is so important.

The amount and length of protection a person can get from both the vaccine and infection depends on several factors, such as:

  • Age
  • Underlying health conditions
  • If you are up to date with COVID-19 vaccines
  • Severity of symptoms if you previously had COVID-19 (People who were hospitalized due to severe COVID-19 tend to build more immunity that people with milder infections, but they pay a bigger price).
  • Differences between the SARS-CoV-2 variant that you were infected with if you previously had COVID-19 
  • Amount of time passed since you were vaccinated or infected. Learn how to get vaccinated

Older adults and people with immunocompromising conditions may develop less protection against COVID-19 from both vaccination and infection due to a reduced immune response and antibody development. Additional doses and booster doses provide the best protection for people at increased risk for severe COVID-19.

Get your booster dose today

For the best protection against COVID-19 and circulating variants, get vaccinated and get your COVID-19 booster dose when eligible.

Learn more about booster doses


211 Wisconsin

Call 211 or 877-947-2211 to get referrals for thousands of services across Wisconsin. For COVID-19 questions, text COVID to 211-211. Language assistance is available.

Resilient Wisconsin

Get help learning how to manage stress and adapt to change with services and support from organizations across the state.

Helpful resources

Find help with housing, income, food, employment, health care, mental health concerns, safety at home, and more—in multiple languages.
Last revised December 15, 2022