At-Home Testing for Infectious Diseases: The Laboratory Where You Live

Interest in at-home testing for infectious diseases is growing. The need for at-home testing, specifically for coronavirus disease 2019 (COVID-19), has been hotly debated in the media, but this is not the first time nor the first infectious indication for which at-home testing has been advocated. At-home testing for infectious diseases such as HIV and other sexually transmitted infections is available and has been vigorously debated. Health equity to marginalized communities and reduction of disease transmission are among purported benefits of widespread availability of at-home testing. A number of questions remain regarding at-home test accuracy and the ability to impact patient outcomes and public health while protecting patient privacy. Here, expert clinical microbiologists, physicians, and public health officials weigh in on these outstanding questions with specific emphasis on newly approved at-home tests for COVID-19 during the global pandemic. Susan Butler-Wu: When it comes to at-home COVID-19 testing in the United States, the majority of Emergency Use Authorizations (EUAs) issued by the Food and Drug Administration (FDA) to date involve at-home collection. By definition, at-home collection involves self-collection of a specimen outside of a healthcare setting and then either shipping it to or dropping it off at a designated location, such that it is tested in a CLIA-certified high-complexity laboratory. Some at-home collection tests only have authorization for use by prescription, whereas others have authorization for direct-to-consumer testing, and a prescription is not required. More than 50 authorizations for at-home collection have been issued by the FDA since the beginning of the pandemic, and all involve nucleic-acid amplification tests (NAATs), such as RT-PCR. The number of tests with EUA for at-home COVID-19 testing is far more limited by comparison. Unlike at-home collection, EUAs for at-home testing have been issued for both NAAT and antigen tests. There are currently 2 NAAT-based assays with EUA for at-home testing (at the time of writing), and both use reverse transcription followed by isothermal amplification. Both require the use of manufacturer-provided instrumentation and have EUA for over-the-counter (OTC) testing of symptomatic and asymptomatic individuals. There are currently 3 manufacturers with EUA for at-home antigen testing in the United States: Ellume Limited, Abbott Diagnostics, and the Quidel Corporation. The Ellume COVID-19 Home Test is unique among currently authorized at-home antigen tests in that it includes a Bluetooth connected analyzer that requires use of a smartphone app for test interpretation. In contrast, results of the BinaxNow COVID-19 (Abbott) and QuickVue (Quidel) tests rely on visual inspection for test interpretation. The Ellume test has authorization for OTC testing, while the BinaxNow and QuickVue assays have both OTC and prescription-based offerings. Although all 3 manufacturers’ tests are authorized for symptomatic testing, only the Ellume test is authorized for single testing for asymptomatic screening. In contrast, the EUAs granted for Abbott and Quidel for OTC use specify that serial testing should be performed 1 to 3 days apart for asymptomatic screening, depending on the test. Kimberle Chapin: There has been a rapid evolution for tests to detect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Initially, all COVID-19 testing involved provider-collected specimens, and all testing was performed in CLIA-certified laboratories. As the pandemic progressed, public health was compromised when the demand for testing was not aligned with the supply. As the unprecedented demand for COVID-19 testing continued, approvals of traditional testing and capacity building, along with the inability to access and be seen by providers coupled with long test report times, created the perfect storm for many suppliers to not only commercialize COVID-19 tests but also develop new ways for patients to access tests and services. Today, several self-collection and home testing options for COVID-19 exist in the United States (as described in the FDA In Vitro Diagnostics EUAs—Molecular Diagnostic Tests for SARS-CoV-2 document). The number of tests and collection options with EUA exploded rapidly and changed in 2 important ways. First was in-home collection (with laboratory-based testing) and next, capitalizing on lack of provider access, was in-home testing. The first testing kits for home were offered by multiple commercial laboratories and were self-collected specimens that were sent to a centralized laboratory; these tests required a prescription and were reimbursable. Now, direct-to-consumer specimen collection kits are available through commercial pharmacies or online vendors (e.g., CVS, Walmart, Amazon). Overall, the home collection laboratory-based tests are amplification-based, provide results in 1 to 2 days and direct reporting to patient and public health, and include customer support, reimbursement guidance, and shipping. Almost all home collections are nasal swab specimens. In-home testing, or OTC testing, is also available, and the kits include all supplies to run the test (e.g., swab, test device, instructions). Collection and testing are authorized for symptomatic and asymptomatic people ≥2 years old, and results are available in 15 to 30 min. Currently, there are 3 antigen tests for at-home use; all detect nucleocapsid protein antigen and are lateral flow assays. Two are visually interpreted, and one uses fluorescent technology that requires a smartphone app for interpretation and result transmission to public health. Importantly, negative predictive value compared to high-complexity RT-PCR has a wide range depending on patient population, clinical presentation, and prevalence of disease. Thus, serial antigen testing every 3 days, or twice per week, is recommended to identify infection in early stages. Specificity is reported to be high. Two loop-mediated isothermal amplification tests are authorized by FDA for OTC use; both target the nucleocapsid region of the viral genome and take less than 1 h to provide results. Nitika Pant Pai: Home COVID-19 tests can be conducted by any intended user (anyone with health literacy) in the comfort of their private space (home or workspace). Home-based COVID-19 test kits may also be self-sample collection tests. For example, the Binax Now Home Test (antigen) in the United States can be performed in self-collected swab specimen in those who meet COVID-19 clinical criteria and/or epidemiological criteria. In the United Kingdom and Germany, rapid antigen home tests have also gathered momentum. Users are encouraged to test themselves and their family members frequently. George Turabelidze: Expanding testing with at-home tests enhances pandemic response at the individual (prompt diagnosis improves person’s disease management and protects close contacts) and the community level (improves disease prevalence estimates, timing of prevention measures, lessens healthcare burden). The key question is whether at-home tests are accurate enough to accomplish those goals. However, even if inferior to conventional tests, the epidemiological concept of at-home testing represents a paradigm shift in disease surveillance from seeking to accurately diagnose a single individual at any given time to a testing regimen that emphasizes capture of infected persons while those persons are most infectious. Future real-world data generated from at-home testing experience will be crucial in confirming validity of this concept. Greater convenience of at-home testing may also help communities with limited access to healthcare, as well as promote testing among people who otherwise might not go to a public testing site. The home testing approach works best when it is done in a serial fashion rather than as a 1-time test. The concern with this is that populations impacted the most by COVID-19 could be unable to afford frequent and serial at-home testing. Reducing the cost while maintaining quality of the product is very important going forward. Nitika Pant Pai: If we examine the health system issues faced in controlling the pandemic response in New York and currently in Delhi and many cities in India, the turnaround time to results with an RT-PCR test is a huge bottleneck. It varies between 1 and 5 days, which is not an effective turnaround time in the setting of acute COVID-19 infection; long turnaround time impedes a rapid initiation of treatment and can lead to a rapid deterioration in the clinical condition of some patients. In the mitigation phase of a pandemic, home tests can play a huge role in self-staging COVID-19 in populations with a certain level of health literacy. These tests can help provide a test result in both the asymptomatic and symptomatic phases of the infection. They can reduce long lines at a facility and anxious delays associated with waiting for a test result. They can help individuals self-triage, stage their COVID-19 infection, and manage their infection at home by monitoring their oxygen saturation levels with a pulse oximeter until they get to the point where they need hospitalization. In India, people are not interested in showing up at free testing centers, for fear of contracting the virus at these super spreader centers. Self-tests help allay fear, minimize the possibility of contracting SARS-CoV-2, and triage moderate/severe COVID-19 cases requiring hospitalization from milder cases that can managed at home. With that, they may ease the burden on many overstretched healthcare systems. This is a welcome relief in a pandemic setting. However, regulatory systems must be ready to approve them with an EUA or honor the EUA from other credible agencies and provide the option to individuals to use them fast enough. In areas where access to healthcare is a concern (such as the mountains of Nepal or rural areas of India), rapid antigen tests have already shown a promising uptake. In such settings, quality-assured self-tests can empower communities to stage their infection in the comfort of their own home. However, self-testers should be assisted by a telemedicine line or remotely supervised by doctors. If perchance their COVID-19 condition deteriorates and they require transportation to a hospital, the system should be ready to accommodate them. Self-tests are useless if they do not inform the next step in care (i.e., linkages to treatment and triage). Omai B. Garner: Appropriate sample collection is critical for accurate test results. Home sample collection needs to be as easy as possible. Because of this, only saliva or anterior nares collection is feasible. Instructions for collection must be clear and easy to follow. Evidence for adequate sample collection within the test kit would be a significant improvement over most OTC tests. Susan Butler-Wu: It is important to note that not all specimen types have equivalent sensitivity for SARS-CoV-2 detection. Nasopharyngeal (NP) specimens are widely considered as the gold standard to which all other specimen types are compared but can only be collected by trained healthcare workers wearing specific personal protective equipment and are relatively uncomfortable for the patient. Home collection can involve a variety of specimen types, depending on what has validated for use with the test system. In some cases this is saliva, while for others it includes midturbinate (also known as deep nasal specimens) or anterior nares swabs. Compared with NP swabs, saliva obtained after coughing, midturbinate swabs, and combined anterior nares and oropharyngeal swabs produce the best results, with several studies showing the latter specimen to have similar sensitivity to NP swabs for laboratory-based NAAT testing. Anterior nares are somewhat less sensitive than these specimen types. The reliability of saliva for SARS-CoV-2 detection can be compromised if collection instructions are not carefully followed. It should also be noted that “saliva” is not a single sample matrix; differences in have been described between saliva specimens collected with coughing, by or by the specimen collection Susan Butler-Wu: There is a of data the of at-home specimen collection and/or testing compared to testing performed in a traditional CLIA-certified In 1 at-home collection of midturbinate nasal swabs for RT-PCR was only sensitive compared to NP swabs for symptomatic patients. 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Kimberle Chapin: is The convenience for self-collection and home testing a For there are assays and antigen assays with EUA There are multiple in-home collection options and several at-home tests. many will take the to FDA and what might be required for at-home be as COVID-19 in and the pandemic The of between tests and at-home tests may be even more to even more important to those who do not have healthcare, in and/or are to unprecedented of or need to the next pandemic. will need and and test by or free and available to up with the public health this for of Use of at-home testing in other disease or populations would be test have not seen the of home testing, and and healthcare providers can help their and George Turabelidze: in SARS-CoV-2 infections the question of whether at-home tests are of such antigen tests target nucleocapsid in the less than the it is that antigen test will not be by at in the The of to home testing up early during the COVID-19 in the United States of testing capacity at that As a we could not more accurately the of the pandemic in communities the while some were in the stage of others were not even More all types of home testing, this option may as a testing more A will on home testing for COVID-19 will to In the we will even more demand for testing capacity and of to public health where we need to in pandemic In the when we have healthcare and telemedicine a at-home testing may Nitika Pant Pai: The is for all testing and health associated with have the widespread of health in and and delays in that have to in in the and do in of the where the healthcare are and The virus has and has the in all healthcare systems that were from public COVID-19 has in many However, it has to many to Home testing is a in as a of this It will in the from over time and then In that self-tests can to to and a facility it is Susan Butler-Wu: The availability of at-home testing for infectious and COVID-19 in is a very to be for COVID-19 as well as other home tests for infectious is home testing will ability to detect and to surveillance (e.g., for With at-home tests for COVID-19 are in the United States only to those with to them. 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