Important update: Healthcare facilities
CDC has updated select ways to operate healthcare systems effectively in response to COVID-19 vaccination. Learn more
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.

Seroprevalence Surveys in Special Populations

Seroprevalence Surveys in Special Populations
Updated July 10, 2020
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CDC is learning more about how people in special populations like healthcare workers and first responders have been infected with SARS-CoV-2, the virus that causes COVID-19. This information is being collected through seroprevalence surveys, which use serological (blood) tests to find out if people in a population or community have antibodies to infections, in this case SARS-CoV-2.

Antibodies are proteins that can fight off infections. If antibodies are found, that means there has been a previous infection. Antibody test results are especially important for detecting previous infections in people who had few or no symptoms and might not have been tested while they were infected.

The main purpose of these surveys is to better understand the risk of infection and develop guidance to prevent future exposures for special populations.

Descriptions of the surveys are provided below.

Healthcare Workers and First Responders Survey

Preliminary results are expected in the coming weeks.

About this survey

Since May 18, 2020, CDC has been conducting seroprevalence surveys of antibodies against SARS-CoV-2 among healthcare workers, first responders and public safety personnel in New York City, the Detroit metropolitan area and Rhode Island in response to the COVID-19 pandemic.

These surveys are designed to assess the presence of antibodies against SARS-CoV-2 among healthcare workers, first responders, and public safety personnel to gain a better understanding of their risk for infection with future exposures while continuing to participate in the COVID-19 pandemic response. The assessment will also determine factors that increase the risk of getting SARS-CoV-2 infection among these target populations. Knowing this information may inform recommendations for staff protection during future COVID-19 response activities.