Vaccine Effectiveness


I am nervous about getting the vaccine. Why should I get it?

It is normal to feel uneasy or unsure about getting a new vaccine. But the benefits of getting the COVID-19 vaccine and helping to end the pandemic far outweigh the risks.

  • Worry less: Vaccines are highly protective in preventing severe disease and hospitalization. The vaccines are effective against mild disease with protection ranging from 66-95% depending on the type of vaccine received. You will be helping to protect others around you, both young and old.
  • You will be helping to protect others around you, both young and old.
  • We need about 50% to 80% of the community to get the vaccine in order for it to be effective.

We are all in this together, and for every person that gets the vaccine, we are one step closer to ending the pandemic.

Do I need to continue wearing my mask after I receive the vaccine?

Yes. While experts learn more about the protection that COVID-19 vaccines provide under real-life conditions, it is important for everyone to continue covering their mouth and nose with a mask, washing hands often, and staying at least 6 feet away from others.

Together, COVID-19 vaccination and following the CDC's recommendations for how to protect yourself and others will offer the best protection from getting and spreading COVID-19.

The following recommendations apply to non-healthcare settings. For related information for healthcare settings, visit Updated Healthcare Infection Prevention and Control Recommendations in Response to COVID-19 Vaccination.

Fully vaccinated people can:

  • Visit with other fully vaccinated people indoors without wearing masks or physical distancing
  • Visit with unvaccinated people from a single household who are at low risk for severe COVID-19 disease indoors without wearing masks or physical distancing
  • Refrain from quarantine and testing following a known exposure if asymptomatic

For now, fully vaccinated people should continue to:

  • Take precautions in public like wearing a well-fitted mask and physical distancing
  • Wear masks, practice physical distancing, and adhere to other prevention measures when visiting with unvaccinated people who are at increased risk for severe COVID-19 disease or who have an unvaccinated household member who is at increased risk for severe COVID-19 disease
  • Wear masks, maintain physical distance, and practice other prevention measures when visiting with unvaccinated people from multiple households
  • Avoid medium- and large-sized in-person gatherings
  • Get tested if experiencing COVID-19 symptoms
  • Follow guidance issued by individual employers
  • Follow CDC and health department travel requirements and recommendations

How effective is the vaccine, and when does the vaccine protection begin?

Based on manufacturer data, Pfizer-BioNTech’s vaccine was found to be 94.6% effective against COVID-19 beginning 7 days after the second dose. Moderna's vaccine was found to be 94.1% effective against COVID-19 after receiving two doses and 100% effective against severe COVID-19 disease. Janssen's vaccine was found to be 66.3% effective against symptomatic COVID-19 and 93.1% effective in preventing hospitalizations at 14 days after vaccination. Additional information about effectiveness can be found on the vaccine fact sheets:

Could I test positive for COVID-19 after receiving the vaccine?

No, not as a result of the vaccine alone. The vaccines won't cause you to test positive on viral tests. If your body develops an immune response, which is the goal of vaccination, there is a possibility you may test positive on some antibody tests.

Will there be a test for immunity as a result of the vaccine?

No. The antibody tests currently in use will generally only detect the type of antibody that is produced by natural infection, not antibodies produced by a response to vaccination. Experts are currently looking at how COVID-19 vaccination may affect antibody testing results.

Is it better to get natural immunity to COVID-19 rather than immunity from a vaccine?

No. While having the COVID-19 infection does give some immunity, it is a dangerous option, causing serious illness in many, with debilitating symptoms that can last for months. And it kills at least 1-2% of those who get it. Also, experts think immunity from the disease itself may not be long-lasting. Vaccination is the best protection; it is very safe and provides the best immunity.