Test for Past Infection (Antibody Test)

Antibody tests check your blood by looking for antibodies, which can show if you had a past infection with the virus that causes COVID-19. Antibodies are proteins that help fight off infections and usually provide protection against getting that disease again (immunity). Antibodies are disease specific. For example, measles antibody will protect a person who is exposed again to measles but will have no effect if the person is exposed to mumps.

Con base en cuándo se ha infectado una persona y el tiempo de la prueba, es posible que no se encuentren anticuerpos en una persona que está infectada por el COVID-19. Antibody tests should not be used to diagnose COVID-19. To see if you are currently infected, you need a prueba viral. Viral tests identify the virus in samples from your respiratory system, such as swabs from the inside of your nose.

If you test positive or negative for COVID-19 on a viral or an antibody test, you still should take preventive measures to protegerse y proteger a los demás.

We do not know yet if people who recover from COVID-19 can get infected again. Scientists are working to understand this.

Autoverificador

Una guía para ayudarle a tomar decisiones y buscar la atención médica que necesita

Cómo realizarse una prueba de anticuerpos

Guía para interpretar los resultados de la prueba del COVID-19 [610 KB]: una guía para interpretar los resultados de la prueba y determinar qué medidas tomar.

Antibody tests for COVID-19 are available through healthcare providers and laboratories. Check with your healthcare provider to see if they offer antibody tests and whether you should get one.

What do your results mean?

Si el resultado de su prueba es positivo
- A positive test result shows you may have antibodies from an infection with the virus that causes COVID-19, or possibly from infection with a related virus from the same family of viruses (called coronavirus), such as one that causes the common cold.
- We do not know 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.
- Talk with your healthcare provider about your test result and the type of test you took to understand what your result means. Your provider may suggest you take a second type of antibody test to see if the first test was accurate.
- You should continue to protegerse y proteger a los demás since it’s possible you could get infected with the virus again.
- If you have no symptoms, you likely do not have an active infection and no additional follow-up is needed.
  - If you work in a job where you wear personal protective equipment (PPE), continue wearing PPE.
- Si usted tiene síntomas and meet other criteria for testing, you would need another type of test called a prueba viral. This test identifies the virus that causes COVID-19.
  - Esta prueba utiliza muestras respiratorias, como hisopado de la nariz, para confirmar el COVID-19.
  - An antibody (blood) test cannot tell if you are currently sick with COVID-19.
- You might test positive for antibodies even if you never had symptoms of COVID-19. This can happen if you had an infection without symptoms (also called an asymptomatic infection).
Si el resultado de su prueba es negativo
- You may not have had COVID-19 before. Talk with your healthcare provider about your test result and the type of test you took to understand what your result means.
- You could still have a current infection.
  - The test may be negative because it typically takes 1 to 3 weeks after infection to develop antibodies. It's possible you could still get sick if you have been exposed to the virus recently. Esto significa que igual podría propagar el virus.
  - Algunas personas demoran más en crear anticuerpos e incluso algunas directamente no crean anticuerpos.
- Si usted tiene síntomas or develop symptoms after the antibody test and you meet other criteria for testing, you would need another type of test called a prueba viral. Esta prueba utiliza muestras respiratorias, como hisopado de la nariz, para confirmar el COVID-19. An antibody (blood) test cannot tell if you are currently sick with COVID-19.

Regardless of whether you test positive or negative, the results do not confirm whether or not you are able to spread the virus that causes COVID-19. Until we know more, continue to take steps to protegerse y proteger a los demás.

Para profesionales de atención médica

For information on evaluating and testing for active infection, see recommendations for reporting, testing, and specimen collection.

For CDC interim guidance on antibody testing in clinical and public health settings, see Interim Guidelines for COVID-19 Antibody Testing.

Trabajo de los CDC en pruebas de anticuerpos

CDC is evaluating commercial antibody tests

CDC is collaborating with other government agencies to evaluate the performance of commercially manufactured antibody tests. Some of these tests have received Emergency Use Authorization from the U.S. Food and Drug Administration (FDA).

Para obtener más información:

Los CDC están llevando a cabo una vigilancia serológica

Los CDC están observando data from antibody tests to estimate the total number of people who have been infected with the virus that causes COVID-19 in the United States. Los CDC también utilizan pruebas de anticuerpos para obtener más información acerca de cómo el sistema inmunitario responde al virus y para explorar cómo el virus se propaga entre las personas que han estado expuestas. La información que los CDC están estudiando surge de varios grupos, incluidos donantes de sangre y contactos del hogar de personas que tuvieron síntomas y fueron diagnosticadas con COVID-19.

Los CDC apoyan la capacidad de laboratorios estatales, locales, tribales y territoriales.