Ensuring COVID-19 Vaccines Work | CDC

Ensuring COVID-19 Vaccines Work | CDC


Find new guidance for fully vaccinated people. Find a vaccine if you haven’t been vaccinated.

The CDC has modified its recommendations for those who have received all of their vaccines. Guidelines for Individuals Who Have Been Completely Vaccinated.


CDC recommends schools continue to use the current COVID-19 prevention strategies for the 2020-2021 school year. Find out more

The following is an important update on healthcare facilities

In response to COVID-19 immunization, the CDC has modified a few techniques to run healthcare systems efficiently. Find out more

Here’s where you can get the most up-to-date information:
Frequently Asked Questions about Aquatics
Suggestions for Individuals Who Have Been Completely Vaccinated
COVID-19’s main page

Vaccination for COVID-19 must be effective

Vaccination for COVID-19 must be effective

The information on this page was last updated on May 10, 2021

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![Vaccines are effective](https://www.cdc.gov/coronavirus/2019-ncov/vaccines/images/Vaccines are effective_1.png)

Vaccination Efficiency is a term used to describe how effective a vaccine is

  • In the United States, all COVID-19 vaccinations are currently availableeffective As observed in clinical trial settings, it is effective at preventing COVID-19.
  • Growing evidence suggests that mRNA COVID-19 vaccines give similar protection in real-world situations.
  • COVID-19 immunization is a critical tool in the fight against the COVID-19 pandemic.
  • COVID-19 immunization protects people from becoming ill or dying from COVID-19, and it may also protect those around them.
  • People should get all of the recommended doses of the COVID-19 vaccination to get the best protection.
  • While no vaccination is 100% effective, some persons who have been fully vaccinated against COVID-19 may still become unwell. Specialists are continuing to track and assess how frequently this happens, how serious their disease is, and how likely it is for a vaccinated individual to transfer COVID-19 to others.
  • The CDC advises that you acquire a COVID-19 vaccine as soon as one becomes available.

Are COVID-19 vaccinations effective?
Is it safe to use COVID-19 vaccines?


Associated Research

  • MMWR: Effectiveness of Pfizer-BioNTech and Moderna Vaccines Against COVID-19 Among Hospitalized Adults Aged ≥65 Years — United States, January–March 2021
  • MMWR: Interim Estimates of Vaccine Effectiveness of BNT162b2 and mRNA-1273 COVID-19 Vaccines in Preventing SARS-CoV-2 Infection Among Health Care Personnel, First Responders, and Other Essential and Frontline Workers — Eight U.S. Locations, December 2020–March 2021
  • MMWR: Effectiveness of the Pfizer-BioNTech COVID-19 Vaccine Among Residents of Two Skilled Nursing Facilities Experiencing COVID-19 Outbreaks — Connecticut, December 2020–February 2021

Details on the effectiveness of vaccines

  • COVID-19 Vaccines Are Effective
  • COVID-19 Vaccine Efficacy as Measured by the CDC
  • Why Does the CDC Monitor COVID-19 Vaccine Effectiveness?
  • COVID-19 Vaccine Effectiveness Research at the CDC
  • Following COVID-19 vaccination, there’s a chance you’ll get sick

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