Antibody Testing

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Antibody Testing

Antibody tests detect past infections. Antibody testing is an important way to learn more about this novel coronavirus – how it spreads in the community and the way in which it impacts people differently. The more we learn about the virus, the more we can share and apply this knowledge to reduce the risk of its spread in Sonoma County.

The COVID-19 antibody test is a blood test, also known as a serology test, and is performed by a healthcare professional who takes a sample by drawing blood from a vein in the arm.

The antibody test does not check for the COVID-19 virus itself – only a viral test is used to diagnose someone who is currently sick. Instead, it detects the presence of antibodies that shows the immune system was activated to respond to the infection.

It is important not to perform the test too early in the course of the infection because It can take as long as three weeks after infection for enough antibodies to build up in the body and be detected by the antibody test.

While the presence of antibodies often indicates immunity, the World Health Organization cautions that there’s a lack of evidence on whether having COVID-19 antibodies signifies that someone is protected against reinfection with the virus. The level of immunity and how long immunity lasts are not yet known. That is why people who have recovered from COVID-19 should still take precautions and practice physical distancing, facial covering, and hand hygiene recommendations.

Free Antibody Tests for Eligible Residents

Sonoma County is conducting free, confidential, antibody testing and encourages residents who have tested positive for COVID-19 or live with persons who have tested positive for COVID-19 to participate.

To best serve our community, testing will continue to focus on those who have previously tested positive and their contacts. After a brief respite in August due to wildfires, Sonoma County will continue antibody testing in mid-September.

Call today (707) 565-4667 to reserve your appointment.

There is no charge for antibody testing. ID, social security number, and medical insurance are not needed. Test results are confidential and are delivered by phone or email within three weeks.

People currently experiencing COVID-19 symptoms should get a diagnostic (viral) test at one of several locations in the county listed on the Sonoma County Emergency Website.

Frequently Asked Questions

No COVID-19 antibody test is 100% accurate. It’s possible to test negative yet actually have been infected (false-negative result).

While there have been many antibody tests with questionable accuracy on the market since the start of the COVID-19 pandemic, the U.S. Food and Drug Administration (FDA) has removed the majority of them from circulation. The test used in Sonoma County has a high-degree of accuracy–meaning that nearly 98% of those who test positive for antibodies had COVID-19 and nearly 100% of those who test negative did not have the virus.

Antibody testing is an important way to learn more about this novel coronavirus–how it spreads in the community and the way in which it impacts people differently. For example, many people who are infected with COVID-19 never experienced symptoms; they nonetheless may have been contagious and unknowingly spread the virus to others. This information will help us conduct contact tracing and reach out to people who may have had close contact with a person who previously was infected, monitor them for symptoms and get them the care they need while protecting others from exposure. In addition, someone may have tested positive for COVID-19, but never developed antibodies.

The more we learn about the virus, the more we can share and apply this knowledge to reduce the risk of its spread by adopting healthy behaviors such as social distancing, facial covering and hand hygiene until an effective treatment and vaccine are readily available to the public.

People who have recovered from COVID-19 may be eligible to donate plasma, which is a component of blood. This plasma could be used to treat others with severe disease and boost their ability to fight the virus. Doctors call this “convalescent” plasma.

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