Point-of-Care Testing for Infectious Diseases - Now and in the Near Future

Until recently, reliable testing for an acute infection by molecular methods required the patient to be seen by a physician, sampled and the sample to be sent to a microbiology laboratory for testing with a typical total turn-around time to result of more than 24 hours. If a faster result was requested, immunology-based lateral flow near patient testing with results within minutes was an option for some infections, such as Influenza and RSV. However, this came at the cost of inferior sensitivity and specificity compared to molecular-based testing, as highlighted during the COVID-19 pandemic.

We are now facing the most disruptive paradigm shift since the dawn of clinical microbiology— moving rapid molecular testing out of the controlled environment of the diagnostic laboratory and close to the patient—the so-called “Point-of-Care” (PoC) diagnostics. This has been made possible by development of a new generation of molecular diagnostic tests that are easy to use, have performance equal to gold standard laboratory-based molecular tests and will provide a result in less than 30 minutes.

The current PoC tests still require sample processing on an analytical instrument by a trained healthcare individual, but in the near future, a swab may be analyzed directly by the patient on a single-use cartridge powered by e.g., a cellphone battery. The impact on clinical patient management, patient awareness and antibiotic stewardship is not yet fully understood, but the potential is huge but not yet fulfilled. Better use of institutional contact isolation facilities and reduced use of antibiotics has been documented, and increased patient understanding and awareness may improve antibiotic stewardship even further.

The relatively high initial cost per assay as well as the lack of prospective outcome studies and deep understanding of the impact on clinical patient management of PoC is likely the cause of the relatively slow development and market penetration of new assays – which is currently a limiting factor for more widespread use of PoC testing. However, if the diagnostic industry develops sufficient capacity to meet market demands in future epidemics, home-based molecular testing for e.g. Influenza or the next pandemic pathogen may provide an efficient tool for controlling the disease epidemiology compared to testing at local healthcare facilities or regional test centers. 

The demand from physicians as well as from patients for near-patient testing has been steadily rising and in the tail-end of the COVID-19 pandemic, where we will soon reacquaint ourselves with Influenza and RSV, this demand will surely continue to increase. Especially tests with a direct impact on patient management (e.g., whether to contact isolate a patient or whether to prescribe antimicrobial treatment) will likely be widely implemented. The extensive and un-precedented test activity seen during the COVID-19 pandemic may not only have changed the view of healthcare facility managers on infectious disease testing from merely a cost to a necessary part of efficient clinical patient management – but has also brought the concept of diagnostics to the attention of the general population as a highly relevant part of everyday life. As laboratory workers, we no longer have to venture into long (boring) explanations about the importance of our work at dinner parties – we may even find ourselves at the center of attention.

But every coin has a flip side. Diagnostics performed outside the controlled environment of the clinical laboratory, especially tests performed outside healthcare facilities and outside the control and influence of clinical experts – e.g., in pharmacies or in patient homes - may lead to inappropriate use of the diagnostic tests, wrongful interpretation of the test results, lack of quality control procedures, no capture of test results in electronic patient records and compromised local and national surveillance. Moreover, if infectious disease specialists and the clinical microbiology laboratory fail to claim ownership over infectious disease testing no matter where these tests are performed, we will surely miss out on important pieces of the puzzle and we will definitely lose influence on the overall strategy regarding infectious disease testing, use and quality. These downsides may all be addressed by detailed and stringent strategies for implementation, but failure to do so may allow the downsides to overshadow the upsides of this new and exciting technology.