Important update: Healthcare facilities

CDC has updated select ways to operate healthcare systems effectively in response to COVID-19 vaccination. Learn more

Find the latest information:
Aquatics FAQs
Recommendations for Fully Vaccinated People
COVID-19 Homepage

UPDATE

Given new evidence on the B.1.617.2 (Delta) variant, CDC has updated the guidance for fully vaccinated people. CDC recommends universal indoor masking for all teachers, staff, students, and visitors to K-12 schools, regardless of vaccination status. Children should return to full-time in-person learning in the fall with layered prevention strategies in place.

UPDATE

The White House announced that vaccines will be required for international travelers coming into the United States, with an effective date of November 8, 2021. For purposes of entry into the United States, vaccines accepted will include FDA approved or authorized and WHO Emergency Use Listing vaccines. More information is available here.

UPDATE

Travel requirements to enter the United States are changing, starting November 8, 2021. More information is available here.

Science Briefs

Updated Dec. 17, 2021

photo of gloved hand moving lab specimen

COVID-19 Science Briefs provide a summary of the scientific evidence used to inform specific CDC guidance and recommendations. The Science Briefs reflect the scientific evidence, and CDC’s understanding of it, on a specific topic at the time of the Brief’s publication. Though CDC seeks to update Science Briefs when and as appropriate, given ongoing changes in scientific evidence, an individual Science Brief might not reflect CDC’s current understanding of that topic. All Science Briefs are catalogued on this Science Briefs web page as historic reference materials.

COVID-19 Community Levels

Science Brief: Indicators for Monitoring COVID-19 Community Levels and Making Public Health Recommendations

March 4, 2022

This science brief provides an overview of how CDC’s COVID-19 Community Levels framework was developed, the data sources it uses, and how jurisdictions can use the information to monitor COVID-19 Community Levels and inform public health action. A comprehensive approach to assessing COVID-19 community levels can inform decisions about layered COVID-19 prevention strategies, including vaccination and masking, with explicit goals of reducing medically significant disease and limiting strain on the healthcare system.