The clinical benefits of at-home testing for infectious disease

The fundamental question asked by a patient to a clinician is often, “What am I sick with?” With infectious diseases, a diagnostic test is often relied upon to provide an answer and to initiate appropriate management. When a patient is given a diagnosis, it leads to several follow-up actions, all of which apply whether the diagnosis is obtained at home or in a traditional medical setting.

The public health benefit of at-home testing for infectious disease

Despite some lamentations during the COVID-19 pandemic that the advent of home testing diminished the situational awareness of public health authorities and rendered certain metrics such as daily case counts and percent test positivity unreliable, the benefits incalculably outweighed those concerns. The tests, as one advocate often put it, “put the public in public health” because of the actions some individuals took to isolate more rapidly and notify close contacts. Indeed, many public health departments had no way to assimilate home test information, which will be a crucial barrier to overcome to maximize the societal benefit of this approach.

With home influenza, HIV, or STI tests, the same public health benefit will accrue and, over time, will diminish the societal impact of infection and increase public health and patient-centered benefits such as less waiting room or school transmission of influenza, for example.

Also, as mentioned earlier, less inappropriate antibiotic use and more optimal antiviral use will have positive public health benefits by decreasing rates of drug resistance and reducing severe disease that may prompt hospitalization.

Barriers to widespread at-home infectious diseases testing

Although there is great potential for at-home diagnostic testing for infectious disease, important challenges must be resolved to fully realize the potential of these paradigm-shifting technologies.

Test manufacturers should partner with telemedicine platforms and primary care physicians who have televisit capacity to optimize linkage to care and medical treatment. Put simply, the following actions are necessary for optimal delivery of care: (1) Symptom onset prompts a home test. (2)If test is positive, package instructions link to consultation with a telemedicine provider, or the patient can consult their own primary care physician (ie, in person, by telephone, or by video visit). And (3)provider conducts risk assessment and prescription or appointment for antiviral infusion as appropriate. This type of provider-access model would improve uptake and add value; however, linkage to relevant public health authorities is a key challenge. Although anonymity and patient privacy concerns are important in HIV home testing, the use of these tests for respiratory viruses may face less scrutiny. However, as these tests reach commercial markets, developing technological solutions to allow test results to be transmitted to local health departments, state health departments, or the CDC will be crucial, and this capacity is currently lacking with COVID-19 home tests. Such data may need to be anonymized to the ZIP code (or partial ZIP code) level, but these data can still be useful in elucidating the burden of infection in each area and in detecting unusual clusters of positive results.

Another factor in the success of these technologies will be the degree of public uptake. The public may be reticent to incur out-of-pocket costs for a test which, if negative may not directly link to any ameliorating therapy. Determining the price point at which uptake will be maximized is an important task for manufacturers. If insurers and other third-party payers, including the Centers for Medicare and Medicaid (CMS), could be persuaded of the benefits of home testing as means of curbing healthcare costs, it may have a substantial impact on uptake.

Lastly, although these tests may primarily target consumers, this does not preclude their use in medical practices and congregate settings like nursing facilities, schools and colleges, etc, which may increase uptake in the market.

The disruptive vision of success

In the future, I envision a world in which at-home infectious diseases testing is routinized and employed for unequivocal benefits the patient, the clinician, and public health agencies. This future is not far off; the technology already exists and could be realized within 5 years.

A clear linkage with public health information systems is a priority; however, the information gained remains extremely useful even if not all positive results are reported into a database. Tests could include QR codes or Bluetooth technology for voluntary reporting. Public health agencies could partner with a sample of users to gain situational awareness of the incidence of specific infections for which home testing is widely available. Moreover, tests coupled with telemedicine provider visits could be directly reported by clinicians to relevant public health authorities.

Clinical Laboratory Improvement Amendments (CLIA)–waived technology already exists for easy-to-use multiplex panels that individuals could purchase and use at home. An aspirational vision of success is for such devices to be networked and linked to provide (1) a diagnosis to the user, (2) access to a provider for possible treatment, and (3) information to public health agencies. The true potential of such devices could be harnessed in a community outbreak setting as part of mitigation strategies, or to provide early signals that a novel pathogen may be present if multiple individuals with respiratory symptoms test negative for the usual battery of viruses (smart thermometers can provide a similar but less-refined warning ^{Reference Ackley, Pilewski and Petrovic12} ). Additionally, if individuals had such devices at home, public health authorities could distribute new cartridges to users to test for novel pathogens in the event of an outbreak. Myriad potential public health benefits will result from better management of outbreaks of both routine and novel respiratory pathogens with expanded home testing. Such a scenario is not currently being pursued or evaluated, but it is a paradigm to advocate.

Health authorities could also deploy such tests to sentinel populations to monitor disease activity among these groups. Akin to distributing HIV testing kits to individuals at high risk for HIV acquisition, agricultural workers who have high-risk contact with animals, frequent travelers, nursing home residents, and other groups could be monitored more closely with such tests with close follow-up of positive results.

Although antiviral medications provide a major incentive for influenza and COVID-19 diagnostic testing, they do not exist for most other respiratory viruses. Attention given to COVID-19 and influenza testing can spread to other diagnostics for viruses that are typically neglected in formal surveillance activities, such as respiratory syncytial virus, which is not a uniformly reportable condition in all states. By understanding the burden of these other viruses, an incentive for the development of antivirals and vaccines targeting these other pathogens may develop.

Barriers to this future state include costs, public uptake, regulatory agency buy-in—all of which are surmountable. As medicine moves into the 21st century and amazing technology has become ubiquitous in most homes, the advancement of medical diagnostics for infectious diseases in the home setting is overdue.