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University Library, University of Illinois at Urbana-Champaign

COVID-19 Vaccines

Information and evidence about COVID-19 vaccine efficacy and safety

HOW VACCINES WORK

COVID-19 vaccines teach our immune systems how to recognize and fight the virus that causes COVID-19. It typically takes two weeks after vaccination for the body to build protection (immunity) against the virus that causes COVID-19. That means it is possible a person could still get COVID-19 before or just after vaccination and then get sick because the vaccine did not have enough time to provide protection.  People are considered fully protected two weeks after their second dose of the Pfizer-BioNTech or Moderna COVID-19 vaccine, or two weeks after the single-dose Johnson & Johnson’s Janssen COVID-19 vaccine.

You should keep using all the tools available to protect yourself and others until you are fully vaccinated. After you are fully vaccinated, you may be able to start doing some things you had stopped doing because of the pandemic. Learn more about what you can do when you have been fully vaccinated.

SOURCE - CDC https://www.cdc.gov/coronavirus/2019-ncov/vaccines/keythingstoknow.html (April 15, 2021)
 

VACCINE EFFECTIVENESS

What We Know

  • COVID-19 vaccines are effective at keeping you from getting COVID-19.
  • After you are fully vaccinated, you may be able to start doing some things you had stopped doing because of the pandemic.

Studies show that COVID-19 vaccines are effective at keeping you from getting COVID-19. Getting a COVID-19 vaccine will also help keep you from getting seriously ill even if you do get COVID-19.

COVID-19 vaccination is an important tool to help us get back to normal. Learn more about the benefits of getting vaccinated.

SOURCE: CDC https://www.cdc.gov/coronavirus/2019-ncov/vaccines/keythingstoknow.html (April 15, 2021)

What We Are Still Learning

  • Scientists are still learning how well vaccines prevent you from spreading the virus.
  • We’re also still learning how long COVID-19 vaccines protect people.

Although COVID-19 vaccines are effective at keeping you from getting sick, scientists are still learning how well vaccines prevent you from spreading the virus that causes COVID-19 to others, even if you do not have symptoms. Early data show the vaccines do help keep people with no symptoms from spreading COVID-19, but we are learning more as more people get vaccinated.

We’re also still learning how long COVID-19 vaccines protect people.

For these reasons, people who have been fully vaccinated against COVID-19 should keep taking precautions in public places, until we know more, like wearing a mask, staying 6 feet apart from others, avoiding crowds and poorly ventilated spaces, and washing your hands often.

SOURCE: CDC - https://www.cdc.gov/coronavirus/2019-ncov/vaccines/keythingstoknow.html (April 15, 2021)