Science brief: Background rationale and evidence for public health recommendations for fully vaccinated people
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Science brief: Background rationale and evidence for public health recommendations for fully vaccinated people

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  • English

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    • Description:
      Updated Apr. 2, 2021

      Key Points

      • COVID-19 vaccines currently authorized in the United States are effective against COVID-19, including severe disease.

      • Preliminary evidence suggests that the currently authorized COVID-19 vaccines may provide some protection against a variety of strains, including B.1.1.7 (originally identified in the United Kingdom). Reduced antibody neutralization and efficacy have been observed for the B.1.351 strain (originally identified in South Africa). However, across studies, antibody neutralizing activity of sera from vaccinated people was still generally higher than that observed for convalescent sera from people who have recovered from COVID-19.

      • A growing body of evidence suggests that fully vaccinated people are less likely to have asymptomatic infection and potentially less likely to transmit SARS-CoV-2 to others. However, further investigation is ongoing.

      • Modeling studies suggest that preventive measures such as mask use and social distancing will continue to be important during vaccine implementation. However, there are ways to take a balanced approach by allowing vaccinated people to resume some lower-risk activities.

      • Taking steps towards relaxing certain measures for vaccinated people may help improve COVID-19 vaccine acceptance and uptake.

      • The risks of SARS-CoV-2 infection in fully vaccinated people cannot be completely eliminated as long as there is continued community transmission of the virus. Vaccinated people could potentially still get COVID-19 and spread it to others. However, the benefits of relaxing some measures such as testing and self-quarantine requirements for travelers, post-exposure quarantine requirements and reducing social isolation may outweigh the residual risk of fully vaccinated people becoming ill with COVID-19 or transmitting the virus to others.

      • At this time, there are limited data on vaccine protection in people who are immunocompromised. People with immunocompromising conditions, including those taking immunosuppressive medications, should discuss the need for personal protective measures after vaccination with their healthcare provider.

      • See updated guidance for fully vaccinated people including updated public health recommendations for domestic and international travel. This updated science brief reflects recent changes to the guidance document and will continue to be updated as more information becomes available.

    • Content Notes:
      COVID-19 Vaccinations Demographic Data Definitions -- Historical Updates.
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