Question: When to use SARS-CoV-2 viral test versus serology (antibody) test when both have received EUA from FDA?

Answer passage (source: CDC):
page_title: Frequently Asked Questions about Laboratory Testing and COVID-19
section_headers: For All Laboratories: Accessing Laboratory Testing
Under what circumstances should laboratories use either a SARS-CoV-2 viral or serology (antibody) test that has received EUA from FDA?
section_content: FDA has authorized EUAs for both viral and antibody tests for COVID-19. Viral
(nucleic acid and antigen) tests are used to diagnose the presence of SARS-
CoV-2 infections. In contrast, antibody tests can detect IgG, IgA, and IgM
antibodies from an immune response to SARS-CoV-2.
Whenever possible, laboratories should rely on viral tests to diagnose the
presence of SARS-CoV-2 infections. However, a negative result from viral
testing does not rule out COVID-19.
Most of the PCR-based tests that use two or more targets are likely to have
high specificity (few false positives). However, there is some variation in
the stated sensitivity of the different assays, and sensitivity is highly
dependent on the stage of the disease. For this reason, negative results
should always be interpreted in the context of the exposure history and
symptoms of the patient.
Results from antibody testing should not be used to diagnose or exclude SARS-
CoV-2 infections or to inform infection status. Negative results from antibody
testing do not rule out SARS-CoV-2 infections, particularly for those
individuals who have been exposed to the virus and are still within the
estimated incubation period. Until the performance characteristics of antibody
tests have been evaluated, it is possible that positive results from such
testing may be due to past or present infections with a coronavirus other than
SARS-CoV-2.
If a laboratory initially uses antibody testing for diagnostic purposes,
follow-up testing using a viral test should be performed.
Read: Important Information on the Use of Serological (Antibody) Tests for
COVID-19: FDA Letter to Healthcare Providersexternal
icon
More: FDA EUA Authorized Serology Test Performanceexternal
icon

Reviewer feedback on this answer:
Provides directly relevant answer to the question, while also providing links for further reading and education.
This is a great answer. It responds directly to the question being asked. It tells you how to interpret the test results and links to important information about the specific test being asked about

Reviewer ratings:
Excellent
Excellent

Answer passage (source: CDC):
page_title: Frequently Asked Questions about Laboratory Testing and COVID-19
section_headers: For All Laboratories: Serology
Will CDC submit its antibody test for an EUA?
section_content: Not at this time. CDC is using its antibody test as part of a multi-agency
study to evaluate current commercially marketed antibody tests for specificity
and sensitivity and to help determine how results from antibody tests could
support policymaking. CDC will share information publicly on the recommended
use of antibody testing as soon as enough data becomes available.

Reviewer feedback on this answer:
Does not directly answer the question about which test to use, but provides a somewhat-relevant answer regarding the current state of testing according to the CDC.
The question is asking about when to use the antibody test and this answer is talking about policymaking with the CDC. It doesn't seem relevant and doesn't make that much sense

Reviewer ratings:
Could be Improved
Could be Improved

Answer passage (source: CDC):
page_title: Frequently Asked Questions about Laboratory Testing and COVID-19
section_headers: For All Laboratories: Serology
Should I test for IgG, IgM, or total immunoglobulin?
section_content: The decision to test for IgG, IgM, or total immunoglobulin, which could also
include IgA, depends on the purpose for testing. Testing for total
immunoglobulin may increase sensitivity for identifying people who have been
recently infected. Testing for IgG may be a better marker of durable immunity
to SARS-CoV-2. However, we need additional data on the maturation of the
immune response to SARS-CoV-2 to make evidence-based recommendations for all
testing scenarios. Scientists from CDC and elsewhere are investigating how
SARS-CoV-2 antibody responses develop over time.

Reviewer feedback on this answer:
It talks about some of the testing that's available but doesn't really get to the question about when the person should use the test which is what's being asked in the question
Provides partial answer regarding the current status of antibody testing, but does not provide an answer that advises when to use which test in a given situation.

Reviewer ratings:
Could be Improved
Could be Improved