Diagnostic Testing for Respiratory Viruses – 25 Years of Progress

Diagnostic testing for respiratory viruses has come a long way in the past 25 years. It’s now possible to accurately diagnose many respiratory viruses at the Point of Need (PoN) in just 30 minutes, thanks to the development of multiplex PCR testing. Here, Jonathan O’Halloran, CEO of QuantuMDx, looks at key developments in the past few decades and their implications for the future.


Diagnosing respiratory infections 25 years ago…


Throughout the 1990s, the approach to diagnosing respiratory viruses saw significant improvements, thanks to the adoption of molecular testing. This was the time when nucleic acid amplification tests (NAATs), that had first emerged in the 1980s to diagnose HIV and chlamydia, began to be applied to the testing process for respiratory viruses.1

NAATs, in combination with a method called multiplex amplification, enabled the transition from traditional diagnostic testing methods to molecular ones. And, when SARS-CoV emerged in 2003, the importance of NAATs and multiplex amplification would really come to the fore. Let’s take a closer look at what these developments meant for the diagnosis and treatment of respiratory viruses.1


‘Multiplex amplification’ describes the process of amplifying more than one target sequence using more than one pair of primers, which makes molecular testing more cost-effective than its traditional counterpart and improves its diagnostic capacity. For example, a wide range of respiratory infections can be tested for simultaneously.2

 

One giant leap for diagnostics…


One of the key NAAT procedures is the polymerase chain reaction (PCR), invented by Dr Kary B Mullis and for which, in 1993, he received The Nobel Prize in Chemistry ‘for contributions to the developments of methods within DNA-based chemistry’.3

Mullis was working as a DNA chemist at a biotech company when he had the idea of using primers to select a particular sequence of DNA, and a DNA polymerase enzyme to copy it – the process central to PCR. A heat stable DNA polymerase is cycled through sequences of heating and cooling to amplify DNA, creating millions of copies of a chosen sequence, which can then be used for analysis or experimentation.4


Since then, and in particular over the past 25 years, the sensitivity and specificity of tests to detect viral respiratory pathogens has continued to improve.


When QuantuMDx was founded in 2008, the molecular diagnostics landscape was still largely dominated by conventional, lab-based testing. Though molecular assays’ accuracy was improving, they still depended on largely manual processes, carried out by highly-trained technicians, working in well-equipped laboratories – and with lead times to match. 

Since then, advances in technology have enabled the development of multiplex PCR tests at the Point of Need (PoN) that, today, can provide rapid and highly accurate results.5


Delayed diagnosis carries many negative consequences…


The lengthy lead times for conventional lab-based PCR tests can have a tangible impact on patient outcomes. A QuantuMDx study of care homes found that, during the COVID-19 pandemic, home managers were waiting up to four days for PCR results to be confirmed by laboratories.6


If a person has a suspected infection, this length of time can be critical. They may have to wait in isolation for results to come back, which can cause loneliness and anxiety. This was a particular issue for vulnerable people in care homes during the COVID-19 pandemic. For those in employment, it may be necessary to take time off work, which can negatively impact the individual’s earnings and even the economy as a whole.


Moreover, while waiting for lab results, patients are at risk of becoming more ill, being prescribed incorrect medication – and even death. All these serious outcomes could be avoided if a correct diagnosis could be reached sooner.5

PoN testing, on the other hand, can alleviate the pressure on healthcare providers, and contribute to better health outcomes, by enabling initial consultation, diagnosis, and the prescribing of treatment in a single appointment.


QuantuMDx innovating at the Point of Need…


Launched in 2021, QuantuMDx Q-POCTM multiplex PCR testing platform represents a significant step forward from lab-based PCR solutions. Highly portable, battery-powered, and easy-to-use, Q-POC delivers results in just 30 minutes – significantly shortening the time to diagnosis for a variety of conditions.


Rapid PoN multiplex PCR testing, with devices such as the Q-POC, opens the door to improved resource planning, can contribute to better health outcomes in communities, can help to keep personnel healthy and in work, and – vitally – stands to reduce burdens on healthcare systems all over the world. The Q-POC currently tests for SARS-CoV-2 (COVID-19). In addition, there are respiratory panels that are set for release later this year which test for for SARS-CoV-2, Flu A, Flu B and RSV. There is a further pipeline of multiplex assays under development which will further widen the range of diseases that Q-POC can diagnose such as sexually transmitted infections and gastrointestinal conditions.


The past 25 years have seen PCR analysis moving from the margins of healthcare, to become a key weapon in the fight against infectious disease. Democratising access to diagnostic testing, by enabling gold-standard multiplex PCR testing at the PoN, is an exciting development for global public health – both today and into the future. Beyond the health benefits for individuals, rapid, accurate test results can keep all kinds of businesses and services functioning during challenging times – the positive economic and health impacts of which are enormous.


References:

  1. Mahony JB. Detection of respiratory viruses by molecular methods. Clin Microbiol Rev. 2008;21(4):716-747. doi:10.1128/CMR.00037-07
  2. The Nobel Prize in Chemistry 1993. Available at: https://www.nobelprize.org/prizes/chemistry/1993/summary/ Accessed March 2022.
  3. Royal Society of Chemistry. Chemistry World. PCR inventor Kary Mullis dies aged 74. Available at: https://www.chemistryworld.com/news/pcr-inventor-kary-mullis-dies-aged-74/3010840.article Accessed March 2022.
  4. Elnifro EM, Ashshi AM, Cooper RJ, Klapper PE. Multiplex PCR: optimization and application in diagnostic virology. Clin Microbiol Rev. 2000;13(4):559-570. doi:10.1128/CMR.13.4.559
  5. Zumla A, Al-Tawfiq JA, Enne VI, et al. Rapid point of care diagnostic tests for viral and bacterial respiratory tract infections-needs, advances, and future prospects. Lancet Infect Dis. 2014;14(11):1123-1135. doi:10.1016/S1473-3099(14)70827-8
  6. QuantuMDx blog post. Available at: https://www.quantumdx.com/blog/covid-19-testing-rules-for-care-homes/ Accessed March 2022.
  7. Kim, H., Huh, H.J., Park, E. et al. Multiplex Molecular Point-of-Care Test for Syndromic Infectious Diseases. BioChip J 15, 14–22 (2021). https://doi.org/10.1007/s13206-021-00004-5