Widely available, accurate and appropriately utilized COVID-19 testing remains one of the keys to successfully responding to the pandemic. On May 21^st, I sent an email to the Alliance regarding testing for COVID-19. The email included the chart to the right which does a nice job of displaying the various testing modalities on a time-line. This article is an update focusing on the three categories of testing with a special emphasis on serology (antibody) testing that your asymptomatic patients may ask you about.

There are 3 broad categories of testing: Diagnostic, Screening and Surveillance. Diagnostic tests are PCR (polymerase chain reaction) tests used for symptomatic patients to confirm that your patient’s symptoms are due to active COVID-19 infection. Screening tests are also PCR tests but are used for asymptomatic patients. In this setting, a negative test in the clinical context of absence of symptoms, absence of fever and absence of recent hi-risk contact makes it highly unlikely that the individual is harboring active virus and thus is safe for transfer to a facility or to proceed with elective surgery. Surveillance tests are also performed on asymptomatic patients to determine if antibodies are present indicative of a prior exposure to the virus. A positive antibody test is NOT indicative of active virus. It is this third category to which I would like to devote the rest of this article.

Patients will be asking you about having COVID-19 testing done. They’ve read about increasing test availability. They’ve seen ads from commercial labs like this one:

They may have had a nonspecific illness over the last 3 months and are now curious as to whether it might have been COVID-19. In general, discourage your patients from having antibody testing done for 3 reasons:

1. There is no scientific evidence that the presence of COVID antibodies confers immunity to reinfection

2. Serologic tests have inherent limitations including a significant risk of false-positive results when disease prevalence is low, which apparently it is in our community. Even among MWHC associates who have worked with COVID-positive patients, surveillance

testing has demonstrated that less than 2% have tested positive for COVID antibodies (which is also a testament to how well we have protected our front-line healthcare workers).

3. Among some of the serology tests out there, there has been a cross-reactivity with other coronaviruses, such as those that cause the common cold (thus also increasing the false-positive rate).

Therefore, as the AMA has stated, there are only 3 appropriate uses for serology (antibody) testing:

1. Population-level seroprevalence studies (as is being done with our MWHC associates and which will be extended to first responders in our community)

2. Evaluation of convalescent plasma donors (and even if you have a patient who has recovered from COVID-19 and is interested in being in donor, there is no need for you to order the test yourself. Simply refer the patient to the American Red Cross who will carry the ball from there, including serologic testing if indicated)

3. Medically necessary, well-defined testing plans for patients working with physicians (e.g. research studies, perplexing cases).

When discussing COVID-19 testing options with your patients, you can take advantage of the opportunity to reinforce measures which we now know are effective in significantly reducing one’s risk of contracting COVID-19 as well as the risk of passing it on to others should they unknowingly be asymptomatic carriers: wearing face coverings, social distancing, frequent handwashing and staying home if not feeling well.

Thank you for your continued invaluable services to our

community during these unprecedented times.