How do the vaccines work?

  • There are three main types of COVID-19 vaccines: messenger RNA (mRNA), protein subunit and vector.
  • All three vaccine types either deliver, or cause our bodies to make, harmless proteins only found on the surface of the COVID-19 virus.
  • After we are vaccinated, our immune system recognizes these proteins as foreign, and it attacks and blocks the virus if we get exposed to it.
Icon of gloved hand blocking COVID-19 particles

Three Main Types of Vaccines

  • mRNA icon

    mRNA is a molecule that tells our bodies to make proteins. mRNA from the COVID-19 virus tells our cells to make harmless proteins just like those on the virus. The Pfizer and Moderna vaccines work this way.

  • Icon of protein vaccines

    Protein subunit vaccines, such as the Novavax vaccine, contain harmless pieces of proteins unique to the COVID-19 virus.

  • Icon demonstrating vector vaccine

    Vector vaccines, like the AstraZeneca vaccine, use another virus that has been made safe. Material from the COVID-19 virus has been inserted inside of it. The material tells our cells to make harmless proteins unique to the COVID-19 virus.

What to expect when you get vaccinated

  • Icon showing vaccine being administered in patient's arm

    The Pfizer, Moderna and AstraZeneca vaccines are given as two shots in the upper arm muscle, three or four weeks apart.*

  • calendar icon

    Typically, it takes about two weeks after the second shot for sufficient immunity to kick in.

  • Icon demonstrating spread of COVID-19

    Even after the vaccination, you might be able to pick up the virus, carry it and give it to others so infection prevention measures are still very important.

*The number of times vaccines made by other companies are given and the way they are given vary.  

Are the vaccines safe?

Although both the Pfizer and Moderna vaccines were developed in a faster than usual process, they were extensively tested for both safety and efficacy. Both vaccines have met Food and Drug Administration (FDA) safety standards and will be carefully monitored to detect any problems or side effects.
Icon demonstrating safety of vaccines

Do the vaccines work?

  • Based on clinical trials, the first two vaccines were shown to be extremely effective at preventing COVID-19: Pfizer (95%) and Moderna (94.1%).*
  • The trials so far show the vaccines are equally effective across age,** gender, race and ethnicity subgroups.
  • The clinical trials were conducted with a diverse group of participants, including people of Asian, Black, Hispanic/Latinx and Native American descent.***
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*As additional clinical trials are completed, we will know more about the efficacy of other vaccines. **The Pfizer vaccine was found to be over 94% effective in adults over the age of 65. ***Among the Pfizer participants, 5% were Asian, 10% were Black, 26% were Hispanic/Latinx and 1% were Native American. Among the Moderna participants, 4% were Asian, 10% were Black, 20% were Hispanic/Latinx and 3% were of other descent.


  • Icon demonstrating vaccine will not cause COVID-19

    The truth: You will not get COVID-19 from the vaccine.

  • Icon of vaccine and DNA

    The truth: The vaccine will not change or damage your genetic information.

  • Icon of COVID-19 prevention measures

    The truth: Even if you are vaccinated, you should still wear your mask, frequently wash your hands and maintain physical distance to help keep everyone safe.

Check with your state and local health departments for information on when the vaccines will be available to you. Visit for more information on the vaccines.
Learn more about the COVID-19 vaccines