In a briefing on Wednesday, Dr Hanson and Dr Caliendo of the Infectious Diseases Society of America relayed the updated recommendations for COVID-19 diagnostic testing.
In a briefing on Wednesday, Infectious Diseases Society of America (IDSA) board of directors members discussed revised recommendations for coronavirus disease 2019 (COVID-19) diagnostic testing.
Kimberly E. Hanson, MD, MHS, associate professor of internal medicine at the University of Utah School of Medicine and member of the IDSA board of directors, and Angela M. Caliendo, MD, PhD, FIDSA, professor and executive vice chair, department of medicine, Alpert Medical School, Brown University, and secretary of the IDSA board of directors, discussed the various means of testing for severe acute respiratory syndrome (SARS-CoV-2), the virus that causes COVID-19.
Hanson and Caliendo are both part of the diagnostics guidance panel and collaborated on 2 guideline documents that were posted on December 23: one that centers around molecular COVID-19 testing using polymerase chain reaction (PCR), which are designed to detect the virus’ genetic material, and another that focuses on antibody testing, which analyzes an individual’s response to infection. Hanson and Caliendo are also currently working on preparing guidance on rapid antigen testing.
With the landscape of COVID-19 research quickly shifting, Hanson, Caliendo, and the IDSA diagnostics guidance panel “monitor new information and new data…to pivot pretty quickly to update our previous recommendations,” Hanson said during the presentation.
The guidance panel analyzed studies comparing sample types, molecular test types, and testing of asymptomatic individuals.
Earlier guidelines released in May recommended that health care professionals use the nasal pharyngeal swab (PCR) test; however, panelists have since identified limitations to this method of testing. For instance, the swab is uncomfortable for patients and providers need to be trained to achieve a useful sample. They must also have the appropriate protective equipment (PPE). In addition, researchers have also since focused on the potential for saliva testing. As a result, the new guidelines suggest collecting a “nasopharyngeal swab, mid-turbinate swab, anterior nasal swab, saliva, or a combined anterior nasal/oropharyngeal swab rather than an oropharyngeal swab alone,” in symptomatic individuals suspected to have COVID-19.2
Hanson explained that this strategy has its complications as well. For example, the availability of diagnostic resources remains a concern. “There still are some supply issues potentially. We’ve had issues on and off getting swabs, and getting 2 is harder than getting 1, even though collecting 2 is better than collecting 1. And I think each individual center will have to tailor the specimen type that they choose based on what resources they have available,” Hanson said. Collection also depends on the setting. Drive-thru testing will have different considerations than the hospital setting.
Caliendo also compared standard molecular testing with rapid tests. She defined the rapid test as a one that can be completed within an hour, not including collecting and transporting the specimen. “Once I have the specimen in my hand, all of the steps of the assay are completed in an hour,” Caliendo said. There are 2 kinds rapid tests: the rapid PCR test and the isothermal rapid test. Rapid tests do not require a trained health care professional to administer it and do not need to be tested in a batch, unlike the standard molecular tests.
Caliendo said that the guidance panel recommended the rapid PCR test and the standard PCR over the isothermal rapid test, since both versions of PCR tests showed an average of 97% sensitivity and high specificity. On the other hand, the isothermal rapid test demonstrated an average of only 80% sensitivity and a higher rate of false negative results.
Regardless, some health centers will have access to the isothermal rapid test. According to Caliendo, “one good thing is that all of these tests have a very high specificity—whether it was rapid PCR, standard PCR, or standard lab based testing, or isothermal, very high specificity. You're not going to see a lot of false positive results,” she said. In addition, although the isothermal rapid tests are outshined by the PCR and rapid PCR tests, “it’s certainly better than not testing at all,” Caliendo continued.
The presentation also touched upon asymptomatic and immunosuppressed individuals, including those undergoing chemotherapy or planning to receive immunosuppressive treatment, as well as those with autoimmune diseases. After reviewing the research, the panel decided to forego a specific recommendation for this population so that physicians can assess their patient on an individual basis.
As for COVID-19 testing that can be done at home, there currently are 2 antigen tests granted emergency use authorization (EUA) by the FDA. Both tests require a smartphone, and 1 requires the test to be completed with a proctor online. Although the trials done on these tests have been relatively small in size and therefore lack a substantial amount of information on their performance, investigators do know that they work better when used within the first week of infection due to the higher viral load, according to Hanson.
As of January 5, there are a total of 258,507,055 COVID-19 test results and nearly 21 million cases of the virus in the US. The updated IDSA guidance aims to meet the critical need for continued review and analysis of research in COVID-19 diagnostics.