What COVID-19 Seroprevalence Surveys Can Tell Us

What COVID-19 Seroprevalence Surveys Can Tell Us
Updated July 8, 2020

Read Text Equivalent (for Section 508 access)

Infographic: A seroprevalence survey uses antibody tests to estimate the percentage of people in a population who have antibodies against SARS-CoV-2. This page includes a graphic explaining how seroprevlance surveys use antibody test to measure the percent of a population likely have a past infections with SARS-CoV-2, the virus that causes COVID-19.

What COVID-19 Seroprevalence Surveys Can Tell Us

Antibody against SARS-CoV-2

Serology, or antibody, testing checks a sample of a person’s blood to look for antibodies against SARS-CoV-2, the virus that causes COVID-19. Antibodies usually become detectable in the blood 1-3 weeks after someone is infected.

Person infected → 1-3 weeks → person has detectable level of antibodies*

*Some people may take longer than 3 weeks to develop antibodies, and some people may not develop antibodies. It is currently unknown how long antibodies are detectable after infection.

A positive result from this test may mean that a person was previously infected with the virus.

Positive (sample positive for SARS-CoV-2 antibodies)

Negative (Sample negative for SARS-CoV-2 antibodies)

Seroprevalence

The percentage of individuals in a population who have antibodies to an infectious agent is called seroprevalence.

Seroprevalence Survey

A seroprevalence survey uses antibody tests to estimate the percentage of people in a population who have antibodies against SARS-CoV-2.

This can tell us how many people in a specific population may have been previously infected with SARS-CoV-2.

A small sample of people participating in the survey represents a larger population, which could be a community, state, or special population (like healthcare workers or pregnant women).