- A viral test tells you if you have a current infection.
- An antibody test tells you if you had a previous infection
An antibody test may not be able to show if you have a current infection, because it can take 1-3 weeks to make antibodies after symptoms occur. We do not know yet if having antibodies to the virus can protect someone from getting infected with the virus again, or how long that protection might last.
How to get an antibody test: Check with your healthcare provider to see if they offer antibody tests.
If you test positive:
- A positive test result shows you have antibodies that likely resulted from an infection with SARS-CoV-2, or possibly a related coronavirus.
- It’s unclear if those antibodies can provide protection (immunity) against getting infected again. This means that we do not know at this time if antibodies make you immune to the virus.
- If you have no symptoms, you likely do not have an active infection and no additional follow-up is needed.
- If you have symptoms and meet other guidelines for testing, you would need another type of test called a nucleic acid test, or viral test. This test uses respiratory samples, such as a swab from inside your nose, to confirm COVID-19. An antibody test alone cannot tell if you definitely have COVID-19.
- It’s possible you might test positive for antibodies and you might not have or have ever had symptoms of COVID-19. This is known as having an asymptomatic infection, or an infection without symptoms.
If you test negative:
- If you test negative for COVID-19 antibodies, you probably did not have a previous infection that has gotten better. However, you could have a current infection. It’s possible you could still get sick if you have been exposed to the virus recently, since antibodies don’t show up for 1 to 3 weeks after infection. This means you could still spread the virus.
- Some people may take even longer to develop antibodies, and some people may not develop antibodies.
- If you have symptoms and meet other guidelines for testing, you would need another type of test called a nucleic acid test. This test uses respiratory samples, such as a swab from inside your nose, to confirm COVID-19. An antibody test alone cannot tell if you definitely have COVID-19.
These test results alone do not confirm if you are able to spread the virus that causes COVID-19. Know how to protect yourself and others.
A6. May an employer administer a COVID-19 test (a test to detect the presence of the COVID-19 virus) before permitting employees to enter the workplace? 4/23/20
The ADA requires that any mandatory medical test of employees be "job related and consistent with business necessity." Applying this standard to the current circumstances of the COVID-19 pandemic, employers may take steps to determine if employees entering the workplace have COVID-19 because an individual with the virus will pose a direct threat to the health of others. Therefore an employer may choose to administer COVID-19 testing to employees before they enter the workplace to determine if they have the virus.
Consistent with the ADA standard, employers should ensure that the tests are accurate and reliable. For example, employers may review guidance from the U.S. Food and Drug Administration about what may or may not be considered safe and accurate testing, as well as guidance from CDC or other public health authorities, and check for updates. Employers may wish to consider the incidence of false-positives or false-negatives associated with a particular test. Finally, note that accurate testing only reveals if the virus is currently present; a negative test does not mean the employee will not acquire the virus later.
Based on guidance from medical and public health authorities, employers should still require - to the greatest extent possible - that employees observe infection control practices (such as social distancing, regular handwashing, and other measures) in the workplace to prevent transmission of COVID-19.
Additional Guidance: Return to Work Medical Inquiries, Doctor's Notes & Documentation