FAQs on Testing for COVID-19 / SARS-CoV-2
Q: When is the best time to test for COVID-19 following an exposure?
A: The optimal time to test for COVID-19 following exposure is uncertain; five to seven days following exposure is recommended based on the average incubation period.
Q: What advice should be given to patients with known or presumed COVID-19 managed at home?
A: For most patients with COVID-19 who are managed at home, we advise the following:
- Supportive care with antipyretics/analgesics (eg, acetaminophen) and hydration
- Close contact with their health care provider
- Monitoring for clinical worsening, particularly the development of new or worsening dyspnea, which should prompt clinical evaluation and possible hospitalization
- Separation from other household members, including pets (eg, staying in a separate room when possible and wearing a mask when in the same room)
- Frequent hand washing for all family members
- Frequent disinfection of commonly touched surfaces
Q: What is the difference between surveillance, screening, and diagnostic testing for COVID-19 testing?
A: Surveillance for COVID-19 includes ongoing systematic activities, including collection, analysis, and interpretation of health-related data, essential to planning, implementing, and evaluating public health practice. It is generally used to monitor for an occurrence, such as an infectious disease outbreak, in a population or community, or to characterize the occurrence once detected, such as looking at the incidence and prevalence of the occurrence.
Screening for COVID-19 is looking for an occurrence at the individual level even if there is no individual reason to suspect infection such as a known exposure. This includes a broad screening of asymptomatic individuals without known exposure with the intent of making individual decisions based on the test results. Screening tests are intended to identify infected individuals prior to the development of symptoms or those infected individuals without signs or symptoms who may be contagious so that measures can be taken to prevent those individuals from infecting others.
Diagnostic testing for COVID-19 is also looking for an occurrence at the individual level but is performed when there is a particular reason to suspect that an individual may be infected. Diagnostic tests are intended to diagnose an infection in patients suspected of COVID-19 by their healthcare provider such as in symptomatic individuals, individuals who have had a recent exposure, individuals who are in a high-risk group such as healthcare providers with known exposure, or testing to determine the resolution of infection. Diagnostic tests may also be appropriate in areas of high community spread, at the discretion of the ordering healthcare provider. FDA regulates diagnostic tests as in vitro diagnostic devices and has provided recommendations and information regarding EUA requests for COVID-19 diagnostic tests in the Policy for Coronavirus Disease-2019 Tests and the EUA templates referenced in that Policy.
Q: Are antibody, or serology, tests used to diagnose SARS-CoV-2 infection?
A: The terms “serological” or “antibody” tests are generally used to refer to tests that detect antibodies to the SARS-CoV-2 virus. Because the antibodies are part of the body’s immune response to exposure and not the virus itself, such COVID-19 testing cannot be used for the diagnosis of infection. Based on the underlying scientific principles of antibody tests, we do not expect that an antibody test can be shown to definitively diagnose or exclude COVID-19 infection. SARS-CoV-2 antibody tests are intended for use as an aid in identifying individuals with an adaptive immune response to SARS-CoV-2, indicating recent or prior infection, by detecting antibodies to SARS-CoV-2 in human blood specimens.
Q: Does my facility need a CLIA certificate if we are performing SARS-CoV-2 surveillance testing using a pooled sampling procedure with non-patient-specific reporting?
A: During this COVID-19 Public Health Emergency, facilities performing SARS-CoV-2 surveillance testing using a pooled sampling procedure to report non-patient-specific SARS-CoV-2 cohort results will not require CLIA certification. This testing is not considered by CMS to be diagnostic of SARS-CoV-2 infection, and participants should not rely on information received from this type of testing for decision-making purposes.
Q: What is the difference between Molecular and Antibody tests?
A: Comparison of COVID-19 Molecular and Antibody Tests
A: People who receive positive results on an antibody test but don’t have symptoms of COVID-19 or have not been around someone who may have COVID-19 are not likely to have a current infection. They can continue with normal activities, including work, but still take steps to protect themselves and others. People who receive positive results on an antibody test and who are currently or recently sick or have been around someone with COVID-19 should follow CDC recommendations on caring for themselves and protecting others, and when they can be around other people again.