Large-scale Geographic Seroprevalence Surveys

Updated Aug. 14, 2020

Large-scale Geographic Seroprevalence Survey Samples

CDC wants to learn more about the percentage of people in the United States who have been infected with SARS-CoV-2, the virus that causes COVID-19 and to better understand how the virus is spreading through the U.S. population over time. Because infected people can have mild illness or may not get medical care or testing, CDC also wants to use this information to estimate the number of people who have been previously infected with SARS-CoV-2 and were not included in official case counts. To help answer those questions and others, CDC is collaborating with public health and private partners on a variety of seroprevalence surveys of different sizes, locations, populations studied, and purposes.

Seroprevalence surveys use serology tests to identify people in a population or community that have antibodies against an infectious disease. Antibodies are specific proteins made in response to infections. Antibodies are detected in the blood of people who are tested after infection; they show an immune response to the infection. Antibody test results are especially important for detecting previous infections in people who had few or no symptoms. It is not known yet if having antibodies to the virus that causes COVID-19 can protect someone from getting infected again, or, if they do, how long this protection might last. CDC and its partners plan to study this issue.

CDC is conducting seroprevalence surveys called “large-scale geographic seroprevalence surveys” in locations across the United States. The first seroprevalence surveys began in areas that first reported community transmission of SARS-CoV-2 in the United States; they are now being expanded to more regions. Descriptions of these surveys are provided below.

Commercial Laboratory Survey

Results from ten sites

CDC has received results from all of Connecticut, Louisiana, Minnesota, Missouri, the New York City metro area, Philadelphia, San Francisco Bay area, South Florida, Utah and Western Washington State from blood samples collected by commercial laboratories as part of routine patient care. In addition, CDC has results from a 2nd and 3rd later, time period, which are included on the interactive website.

As more data become available, tables and data charts will be added to this page to show the early antibody test results for patient specimens tested in these areas.

This survey will continue to collect additional samples from selected areas over time.
- Results from a 2nd period of specimen collection (“Round 2”) are shown for 8 of 10 sites.
- Results from a 3rd period of specimen collection (“Round 3”) are shown for 7 of 10 sites.
The survey will expand to include testing of samples from patients in additional geographic areas.
The interactive dashboard below will be regularly updated as new seroprevalence survey results become available.

View Results

Blood Donor Survey

Preliminary results are expected in the coming weeks.

CDC Seroprevalence Survey Types

CDC is collaborating with public health and private partners on a variety of surveys of different sizes, locations, populations studied, and purposes. The seroprevalence surveys CDC is conducting include: