Screening asymptomatic people regardless of known or unknown COVID-19 exposure is useful, but it will be important to ensure that this testing is used appropriately and that contingency plans are in place to modify operations based on test results.
The Centers for Disease Control and Prevention (CDC) now designates two categories of asymptomatic individuals in the five populations for which SARS-CoV-2 testing with viral tests (i.e., nucleic acid or antigen tests) is appropriate:
- asymptomatic individuals with recent known or suspected exposure to SARS-CoV-2 to control transmission; and
- asymptomatic individuals without known or suspected exposure to SARS-CoV-2 for early identification in special settings.
Revisions to the CDC’s “Overview of Testing for SARS-CoV-2” are timely, considering the US Food and Drug Administration’s (FDA) first emergency use authorization (EUA) announced July 24 for a diagnostic test for the screening of people without known or suspected COVID-19 infection.
“The FDA reissued the LabCorp COVID-19 RT-PCR Test EUA to expand use of the test to anyone, after the company provided scientific data showing the test’s ability to detect SARS-CoV-2 in a general, asymptomatic population,” stated the FDA in the release. With this authorization are two new indications for use: one for testing those who do not have COVID-19 symptoms or who have no reason to suspect COVID-19 infection; the other, to allow pooled sample testing.
FDA Commissioner Stephen M. Hahn, MD, added that this authorization is a “step toward the type of broad screening that may help enable the reopening of schools and workplaces.”
Certain settings, such as schools, high-density critical workplaces, nursing homes, and hospitals, can experience rapid spread of SARS-CoV-2, the virus that causes COVID-19 disease. This is particularly true for settings with vulnerable populations in close quarters for extended periods of time, according to the CDC.
CDC: Testing Asymptomatic People in Special Settings Appropriate
With the updates, the CDC indicated that local health agencies should guide the specific settings in which this testing strategy should be used, stating: “Local, territorial, tribal, and state health departments can help with informed decision-making about testing at these or other settings.” However, before testing large numbers of asymptomatic individuals without known or suspected exposure, “facility leadership should have a plan in place for how they will modify operations based on test results,” the CDC cautioned.
For The Dark Report, the parent publication of COVID-19 STAT, Julia Dahl, MD, of Michigan Medicine Laboratories (MLabs) discussed coronavirus testing in the content of preparing for routine hospital care. (Photo source: MLabs)
Julia Dahl, MD, the Associate Director at Michigan Medicine Laboratories (MLabs), provided insights into how hospitals are approaching the testing of asymptomatic individuals where the SARS-CoV-2 exposure status is unknown. MLabs is part of the University of Michigan Health System, in Ann Arbor.
Dahl: COVID-19 Testing in the Context of Preparing for Routine Hospital Care
“When hospitals open up, we’ll want to test patients coming in for care that’s not COVID-related—meaning surgical and other patients,” Dahl explained in an interview with The Dark Report, the parent publication of COVID-19 STAT. “Re-opening medical facilities for non-COVID care while providing a safe environment for patients, providers, and staff will require expansion of testing to asymptomatic people with results available as quickly as possible.”
Dahl addressed how SARS-CoV-2 diagnostics tests should be used as a screening tool. “When planning for pre-procedure or pre-admission testing, consider the requirement that the result of this COVID-19 test is valid only as long as those patients are quarantined and everyone else in their quarantine environment also is quarantined.
“Since it’s difficult to ensure that patients remain isolated after a COVID-19 test unless they are already admitted, it makes little sense to test these patients for the virus well before the day of surgery,” she explained. “Testing several days or more than a week prior to surgery requires that patients—and all of their at-home contacts—must stay at home and not go out before their admission for surgery or treatment.
“We know this to be true because we’ve had instances of patients who arrived sick at our hospital, had a nasal swab specimen drawn, and a negative result for COVID-19, or they had a different coronavirus,” Dahl explained. “But when we tested these patients three days later, they had a new exposure to COVID-19 and the SARS-CoV-2 was positive at that time.
“If patients and their contacts cannot be assured of complete quarantine between the test collection and arriving for the procedure, then our lab’s testing plan can shift to providing testing immediately prior to the procedure,” Dahl advised.
“Many facilities are requesting COVID-19 testing days in advance of procedures. That tells us it is absolutely essential to work with our facilities to provide accurate information about COVID-19 test results,” added Dahl. “And we have to explain that if hospital staff are relying on the RT-PCR assay to be a true positive about the exposure and infection risk of COVID 19, then that test must be done on the day those patients arrive at the facility.”
The screening of asymptomatic patents will certainly increase the demand for SARS-CoV-2 diagnostic testing, however, it will be important for clinical facilities to ensure that this testing is used appropriately. Clinical laboratories can provide guidance to facilities on correctly screening patients as part of the pre-procedural or pre-admissions testing process. Clinical laboratories, especially hospital-based labs, should also consider the increased demands that screening testing will create and plan appropriately.
—By Caleb Williams, Editor, COVID-19 STAT
Related Resources:
CDC Guidelines: Overview of Testing for SARS-CoV-2
Lab Directors Develop Plans for Return of Routine Hospital Care
