COVID-19 FAQs

FAQs about Testing in the Time of COVID-19

A great deal of our public attention and private conversations remain focused on testing for COVID-19.  We are encouraged by public health and government officials to get tested and that we need increased testing to understand the pandemic to more safely open our society.   Unfortunately, many of the messages are short sound bites and are thus confusing.  Even the knowledgeable reader/listener must furiously dig for details because some public proclamations can be misleading.  This document is an attempt to clarify some of the critical issues around COVID testing to help you determine whether testing is indicated for you, your family, and/or your employees (if you are an employer).

(Updated 11/30/2020)

For those without symptoms, experts agree the ideal time to test is 8 days AFTER exposure to identify those persons who may have contracted the virus and will spread it to others unknowingly. A negative test does not, however, change the recommendation to quarantine for 14 days after an exposure. It is not possible to “test out of quarantine”.

For those with symptoms, the ideal time to test is on Day 3 of symptoms. If the test is done earlier there may not be enough viral particles in the nose to “trip” the test.

Currently there are two major types of tests.

Swab testing, which includes antigen and PCR, seeks to identify an active infection. A positive swab test is an indication of current or active infection.

Some patients with the virus and/or a positive swab test have active symptoms (fever, cough, shortness of breath, chills, fatigue, headache, muscle pain, sore throat, shaking chills, or new loss of taste or smell, vomiting or diarrhea) while others have NO symptoms (asymptomatic).  In either situation, a patient may test positive and is considered contagious for the disease.  A negative test in a symptomatic patient does NOT guarantee they do not have the disease as there can be problems with the specimen collection or lab error.

Antibody tests (AB) seek to determine if a patient had a prior infection, not an active infection.  Antibodies are of two types: a short lived one which may appear in blood as early as 3 days after the onset of symptoms, and one that persists for a longer period but is not detectable until 14 days after the onset of symptoms.

To learn more about what type of test you need go to https://www.texasmedclinic.com/covid-19-what-test-should-i-get/

Swab testing involves placing a device into either the nose or mouth to collect a specimen.  Initially the most widely used swab test for COVID-19 was a nasopharyngeal (way back in your nose to absorb some mucous in that area) swab.  Other types of swabs have gained acceptance as testing abilities have improved.  Today many swab tests are performed by the patient or parent while the health care professional monitors to ensure the procedure is followed.   Patient self-collections have proven to be effective, require use of less personal protective equipment and are now the primary collection method at most centers.

Antibody tests, commonly referred to as either blood or serum tests (serum is the fluid portion of blood left when all the cells are removed) is the source.  The blood can be obtained typically by removing a tube of blood from the arm.  Finger stick samples for antibody testing are not a good option.

The FDA has not approved any COVID-19 test, either swab or antibody. Several tests among the myriad being marketed which are “authorized” by the FDA (a much lower level of evaluation) under a rule known as Emergency Use Authorization (EUA).

You should ensure that the provider of your test (either antigen or PCR swab test or antibody test) has received FDA EUA before undergoing the test.

Most antigen swab tests are performed inhouse, both specimen collection and lab results.

The swab for PCR tests are performed in house, but specimens are sent to a lab for detection of the virus.

Antibody or AB tests are performed through a blood draw in a clinical setting. The specimen is sent to a lab for detection. Therefore, those considering AB testing should ensure their blood is sent to a lab. Results from finger stick or rapid AB tests are considered unreliable.

Rapid antigen tests are performed entirely within a clinic setting using a fluorescent immunoassay analyzer for the rapid detections of SARS-CoV-2 in a nasal swab specimen. The results are available in as little as 15 minutes.

The test is named Sofia® 2 SARS Antigen FIA and is produced by the Quidel Company.  It was the first company to receive FDA EUA. The accuracy of this test for both positive and negative results has been shown to equal a lab tested swab or PCR test. The authorization for this test is for symptomatic patients in the first five days of their illness.

  • Individuals with signs or symptoms consistent with COVID-19
  • with recent known or suspected exposure to SARS-CoV-2 to control transmission
  • Asymptomatic individuals without known or suspected exposure to SARS-CoV-2 for early identification in special settings
  • Individuals being tested for purposes of public health surveillance for SARS-CoV-2

A positive antigen test means the person tested has the virus, has an active infection, and, in most cases, should be considered actively contagious to others. As such, they should be in isolation. There is evidence that PCR tests can remain positive late in the disease, in some patients, but they are not contagious. Those who tests positive should follow the advice of their physician or health care advisor regarding ending their isolation.

Unfortunately, the answer to this question is unclear.  A positive antibody or AB test is presumed by many to indicate a person has developed resistance and is thus immune to a repeat COVID-19 infection due to a prior infection.  This has NOT been proven with COVID-19.  While there are many types of viral infections for which a patient may produce antibodies either after contracting or being vaccinated against the disease, (i.e. measles, chicken pox) this statement does not apply to every type of viral infection. More time and more research are necessary to understand the meaning of a positive antibody test with COVID 19.

Another concern is that if, in fact, the presence of antibodies does ultimately provide immunity, and it is unclear how long the immunity might last; is it one year?  Three years?  Lifetime (doubtful)?

The public has a great deal of curiosity about antibody testing and many want to “know my status”.  However, if tested, a positive test should NOT be a license to take increased risks with one’s own health or that of others.   A positive test should NOT be used to discontinue or reduce social distancing, hand washing or use of masks.  Until we know more about antibody testing, the behavior of both the positive antibody group and the negative antibody group should remain the same as it has been since the beginning of this disease process.   As noted above, at present we do NOT know if a positive antibody test provides any protection.

An AB test CANNOT be used to determine whether a person does or does NOT have a current infection with COVID-19.

With or without symptoms if you test positive, you must isolate until all three of the following criteria are met:

  • At least 10 days have passed since symptoms first appeared and
  • At least 24 hours have passed since last fever without the use of fever-reducing medications and
  • Symptoms (e.g., cough, shortness of breath) have improved

A negative test should be interpreted by your healthcare provider since false negatives can occur.  A patient testing negative, in the face of symptoms should follow the same return to life guidelines as for the positive test results.

The accuracy of some AB tests has continued to improve with time such that a hand-full of currently available, lab-based tests have a false positive rate of near 0%.  At this level of accuracy, while we at TMC continue to have concerns about the use to which AB test results might be placed, we are now reasonably confident the results of some tests are accurate.  Specifically, we work with our lab partners and provide, a test using serum or plasma drawn from a blood sample, to detect antibodies and determine the body’s immune reaction to SARS-CoV-2.

An antibody test may or may not be considered a covered service by most insurance carriers.  However, given there is no current medical indication, it is not clear if carriers will pay for all or part of the test.  They may determine this is 100% patient responsibility.  As such there may be a direct cost to the patient for the test and any associated medical evaluation.

If deciding to undergo AB testing it is important to find a reputable medical office to provide the test.  This will include obtaining a blood specimen and sending that specimen to a lab for testing.  Office based AB test are not considered reliable, nor are all lab-based AB tests. Expect results to take about 48 hours.

CDC does NOT recommend that employers use antibody tests to determine which employees can work. Antibody tests check a blood sample for past infection with SARS-CoV-2, the virus that causes COVID-19. CDC does not yet know if people who recover from COVID-19 can get infected again. Viral tests check a respiratory sample (such as swabs of the inside of the nose) for current infection with SARS-CoV-2.

CDC has published strategies for consideration of incorporating viral testing for SARS-CoV-2 into a workplace COVID-19 preparedness, response, and control plan.

Swab testing for the presence of the virus is merely a snapshot of a moment in time.  A negative test today does not ensure the person will remain negative tomorrow, or in one or two weeks.  In fact, VERY early in the course of the disease it is possible a person is “incubating” (in the process of developing the infection after an exposure) but the virus is not detectable by testing.  Except in certain unique situations, it is also not practical to test employees repeatedly.

No, as of July 16th the CDC no longer recommends any routine test of cure after a positive before a person returns to their normal environment.  Provided the 3 criteria of at least 10 days since onset of symptoms, no fever for 24 hours and symptoms improving have been met repeat testing is unnecessary.  Not only is it waste of scarce resources, the evidence is that those persons who continue to test positive are no longer contagious.  They merely have viral remnants that cannot infect other present in their secretions.   Further, the Families First Coronavirus Act has clarified that employer required testing is not included in the no cost sharing by patients.  Thus, someone other than the carrier, will need to pay for this type of testing. To learn more, go to https://www.texasmedclinic.com/return-to-work-covid-testing-undercuts-a-precious-resource/

The Center for Disease Control and local metropolitan health districts are the primary up-to-date sources for more information.   Individuals may wish to consult with their personal physician or health advisor.  If none is available, please visit our website at www.texasmedclinic.com to schedule a visit time and meet with a physician expert.

Employers may wish to obtain consulting services from an expert who can evaluate the details of their unique business.  Please contact our Director of Business Development and Marketing, Leah Martinez at lmartinez@texasmedclinic.com or 210-349-5577, Ext 8521 for more details and to learn about options and pricing.

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