COVID 19 Testing Guide for Physicians

Updated May 18, 2022

Information on COVID-19 testing requirements and availability changes frequently. Clinicians are encouraged to review CDC and CMS resources along with the local public health and health system guidance for the most current information. Currently, with the surge in cases due to the Omicron variant, testing and contact tracing may be limited or unavailable.

Free COVID-19 Tests: U.S. households can order eight additional free at-home tests at COVIDTests.gov to slow the spread of COVID-19 variants. 

Who Should be Tested for COVID-19?

The CDC has provided guidance on testing for clinicians. This guidance also provides information on the use of tests for surveillance as well as diagnosis. In general, diagnostic testing should be used for:

• Individuals who have symptoms of COVID-19.
• Individuals who have come into close contact with someone with COVID-19 should be tested to check for infection at least 5 days after they last had close contact with someone with COVID-19. The date of the last close contact is considered day 0.
• Individuals who are not up to date with their COVID-19 vaccines who are prioritized for expanded community screening for COVID-19. 
• Individuals, regardless of vaccination status, who have been asked or referred to get testing by their clinician, state, tribal, local, or territorial health department.

People who have tested positive for COVID-19 within the past three months and who do not have new symptoms don't need to be tested per CDC. 

If Positive Test Result:

• If health care professionals receive a positive test, follow CDC or healthcare system guidance for isolation/quarantine before returning to work. View CDC guidance.
• For patients: 
  • Advise patients to isolate according to current CDC or local public health guidance
  • Provide instructions for management of symptoms and when to seek medical attention for worsening or new symptoms. A confirmatory PCR test is required before prescribing/referring patients for COVID-19 therapeutics. 

If Negative Test Result:

• For patients who have symptoms of COVID-19:
  
  • The result may be a false negative and they should isolate away from others.
• For patients without symptoms who were a close-contact (if known):
  • Patients should quarantine if not vaccinated or are not up to date with vaccination.

Types of COVID-19 Tests Available

Labcorp Seasonal Respiratory Virus RT-PCR DTC Test

The FDA has authorized the first non-presecription COVID-19 test that also detects the flu and RSV. Patients can take their own nasal sample without a prescription and send to Labcorp for results. The test can identify and differentiate multiple respiratory viruses at the same time.

InspectIR COVID-19 Breathalyzer 

On April 14, the FDA issued an EUA for the first COVID-19 diagnostic test that detects chemical compounds in breath samples associated with a SARS-CoV-2 infection. Effectiveness was validated in a large study of 2,409 individuals, including those with and without symptoms.

Molecular Testing (RT-PCR)

Tests used for diagnostic purposes; use reverse transcriptase to create and amplify DNA from SARS-CoV-2 RNA.

• There are now a few molecular tests that are have been classified as waived and can be done as a point of care test. These can be found on the FDA website and are indicated with a “W”. The molecular test is much more specific but false negatives do occur. Use clinical judgement and continue to treat the patient as positive if symptomatic or if there was a known exposure.
• While these tests can detect viral RNA/DNA, they do not distinguish between replicating virus (infectious) and remnants of viral RNA/DNA.

The CDC has developed patient fact sheets  and health care worker fact sheets for the available molecular tests.

Antigen Testing

• The FDA has granted EUA to several antigen tests, which detect viral proteins in the nasal cavity. All laboratory settings (high, moderate, and waived) can run this test.
• Antigen tests are relatively inexpensive and can be used at the point of care but are less sensitive than PCR and may result in false negatives.
• Antigen test result interpretation depends on several factors including the stage of infection, performance characteristics of the test (e.g. sensitivity and specificity), and the prevalence of COVID1-9 in the community. The CDC has provided interim guidance  for antigen testing at the individual and community screening.
  - In general, a positive antigen test is most likely reliable given the high specificity of currently available tests
  - A negative test is less reliable due to lower and more varied sensitivity values among the different tests.
  - Negative tests should be considered presumptive and confirmed with RT-PCR when the pretest probability is high and the patient has symptoms or a known exposure.
  -- Confirmation should be done within 2 days if possible.
  -- If PCR testing is not available, patients should isolate.
  
  
• The CDC has provided additional information and an algorithm for use of antigen testing in long-term care facilities (nursing homes). 

Serological (Antibody) Testing - Detects past infection 

Tests detect the presence of IgM and IgG antibodies against SARS-CoV-2, the virus that causes COVID-19.

• Currently, there are several test kits granted Emergency Use Authorization by the FDA.
• The CDC has recently developed its own serologic test that will be used to validate tests from commercial entities and perform surveillance.
• These tests are NOT diagnostic tests and should not be used as such. There is a high potential for false negatives and false positives with these tests. 
• These tests are to be used to show past or present infections, but there is not enough evidence to support that the presence of IgG antibodies to COVID-19 provide short- or long-term immunity to illness, nor whether it reduces the risk of viral shedding in infected individuals.
• These tests are to be used to show past or present infections, but do not confirm the patient has immunity. Some of the tests are not specific enough for COVID-19 infections and will show antibodies for past infections with other coronaviruses. Read the package insert before purchasing.

IgM antibodies are the first to appear and are indicative of a new infection. But it can take days to weeks for these to appear; false negatives can be an issue. False positives are also a concern as there may be cross-reactivity with other coronaviruses. IgG antibodies usually takes at least 4 weeks to appear. These usually show if someone had a past infection but may not be a confirmation of immunity, as they do not measure the effectiveness of a memory response to reinfection. Scientists do not know how SARS-CoV-2 antibodies stay within the body after the infection has cleared.
 

Point of Care COVID-19 Testing

Rapid COVID-19 tests and those that can provide results for patients in the physician’s office (point of care or POC) are appearing on the market. The AAFP supports POC testing that is accurate and reliable, and encourages physicians to stay informed about the tests offered for COVID-19 as the accuracy and reliability varies.

There are multiple tests that have been granted EUA for use in CLIA-specified laboratories. Three tests are now available for use in family physician offices as outlined above. Additionally, the CDC has provided guidance for POC testing.

At Home COVID-19 Testing

To date, there are several home tests given emergency use authorization by the FDA. Please note that the sensitivity of these tests will vary based on the ability of patients to obtain optimal samples. Tests can be purchased at pharmacies or online although availability and prices will vary. Additionally, the federal government is providing free COVID-19 antigen tests (4 per household); consumers can order test online. 

As noted above, rapid antigen tests can produce false negatives, so it will be important to obtain a PCR diagnostic test to confirm infection, particularly if prescribing therapeutics. 
 

SARS-CoV2 Proficiency Tests Available
from AAFP Program

Laboratories need a CLIA certificate to perform COVID-19 testing. Under CLIA, laboratories are prohibited from testing human specimens for the purpose of diagnosis, prevention, treatment, or health assessment without a valid CLIA certificate. To become CLIA-certified, laboratories must comply with the accuracy, quality, and reliability requirements as dictated by the statute.

The CDC has provided more specific information on laboratory testing, interpretation of tests, and FAQs .

Coding and Billing for COVID-19 Testing

The Centers for Medicare & Medicaid Services and the American Medical Association’s Current Procedural Terminology Editorial Panel are creating relevant codes to keep up with the evolving coronavirus testing environment.

The COVID-19 codes are generalized to capture any technique or target. However, determining the correct code for test procedures can be confusing. This quick reference guide can help you determine the correct code for the test procedure. You can also use the AMA CPT Guidance.