What Advances Are Reshaping the Future of Influenza Diagnostic Testing?

Even if you’re not a clinician, you should know how vital influenza diagnostic testing is if you’ve ever experienced a particularly bad flu season.

Researchers and medical professionals are working hard to develop novel ways to test for this deadly respiratory virus.

How Virus Mutations Impact Diagnostic Testing

Influenza mutates rapidly, which can complicate the standard diagnostic testing process. When viruses replicate enough, they genetically change and develop new biological capabilities — meaning they become new strains. Since influenza spreads so quickly, this happens often. 

The two main types of influenza humans have to worry about are A and B. The first is more severe than the second and is the one behind most flu pandemics. Its subtypes are determined by the glycoprotein — haemagglutinin and neuraminidase  — on the virus surface. 

You’ve probably heard of the subtypes H1N1 or H3N2 before. They’re usually the ones you hear about when flu season is upon you. They can be challenging to detect even with highly sensitive, accurate influenza diagnostic testing because of their genetic mutations. 

Many testing methods become significantly less sensitive when new strains appear. For example, antigen tests rely on genetic sequences, so mutations make them less effective. Since influenza strains can differ substantially from one another, diagnosis and treatment can quickly become challenging during flu season.

The Importance of Improving Influenza Diagnostic Testing

Clinical professionals usually have to conduct influenza diagnostic testing when they notice a patient has an influenza-like illness — meaning a sore throat, fever and cough — to prevent the infection from spreading to others and causing an epidemic. 

Those test results influence their decision on whether to start antiviral treatment, perform further tests or control the spread of infection by isolating the patient. Diagnostic testing is critical for protecting the general public’s well-being — but there are still areas where it falls short. 

Accurate and efficient influenza diagnostic testing is critical for keeping the general public safe. There were 14,500 influenza-related deaths during the 2022 to 2023 flu season in England — and there are concerns that the upcoming years will be just as bad, if not worse. 

According to the U.K. Health Security Agency, the 2022 to 2023 flu season had the highest number of deaths since 2018. Experts worry the relaxed social distancing and infection prevention measures might contribute to another influenza epidemic.

Accurate, sensitive and timely tests are essential during flu season. The faster you get your results, the sooner you can start on antiviral treatment and isolation — two very time-sensitive things. 

Why Influenza Diagnostic Testing Needs to Advance

Many of the most common influenza tests have accuracy, speed or sensitivity gaps. For example, both antigen and molecular diagnostic tests can take up to 30 minutes to give results. Half an hour can be the difference between an epidemic and a mild flu season when hundreds of patients present with symptoms simultaneously.

Some of the more accurate influenza testing methods can take hours to complete. For example, reverse transcription polymerase chain reaction (RT-PCR) can take up to eight hours to give results. When time is of the essence, this wait is unacceptable. 

More often than not, clinicians have to make a trade-off between accuracy and speed. While timely methods like rapid influenza diagnosis tests (RDITs) are incredibly fast, they’re not nearly as sensitive as other options. In fact, they’re only 50%-70% sensitive for detecting influenza.

Testing flexibility is essential as clinical professionals prepare for a potentially worse flu season. They need tests that can generate results quickly enough to treat patient and stop the spread while being sensitive enough to pick up on new variants and strains. 

Advances to Existing Influenza Diagnostic Testing

Advances in virus detection and testing are transforming the influenza diagnostic process. 

Bead-Based Microfluid Tests

Using a dropper, you insert a viral sample into the sample inlet on a test stick. There, it mixes with aptamer-coated immunomagnetic beads — magnetic particles coated with antibodies — and detects the presence of influenza A. Results are ready in less than 15 minutes. 

Bead-based microfluid tests shorten the assay duration — the length of the laboratory investigation to measure the presence of a target entity — giving you the readout sooner. They’re one of the most accurate, specific ways to detect respiratory viruses like influenza. 

Biochemiluminescence Reaction-Based Tests

Biochemiluminescence reaction-based tests are accurate and sensitive. The name sounds complex, but the process is relatively simple. When Type A or B influenza is present, the enzyme neuraminidase breaks down in real-time. The resulting chain reaction releases energy in the form of light. Basically, the test glows in response to the virus.

Emerging Influenza Diagnostic Testing Methods

Dedicated research teams are developing novel methods that could forever reshape the future of influenza diagnostic testing. 

SP-IRIS

While the single-particle interferometric reflectance imaging sensor (SP-IRIS) is one research team’s design, other optical sensing techniques exist and are in use today. This particular one captures images in a microarray and then analyses each one to identify the total virus count. 

SP-IRIS can size and count every nanoparticle, meaning it can cover a larger area and work much faster than similar tools. Previous nanoparticle imaging techniques developed for influenza detection are costly and inefficient to use, so this advancement is much needed.

Electrochemical Immunosensor Tests

While electrochemical immunosensor tests have been around for a while, they’re not standard because they’re costly. One research team is changing the game because they found a way to use flexible electrodes on a paper substrate instead of the typical gold-on-ceramic combination.

The researchers used screen-printing to place multiple flexible electrodes on a wax-covered paper substrate so they could test three separate viral samples simultaneously. Results are ready in 20-30 minutes tops. The tests are affordable, highly sensitive, durable and portable. 

Molecular Point-of-Care Tests

Molecular point-of-care (mPoC) tests are fast and accurate — the perfect combination for flu season. They can deliver results in under an hour while maintaining high sensitivity. Now, you can receive antiviral treatment and isolation early enough to protect yourself and others. 

The research team testing mPoC discovered it correctly identified influenza 100% of the time, while the other tests only achieved 59% accuracy. Consequently, the researchers were able to start antiviral treatment in one hour — five hours earlier than the standard.

Influenza Testing Is Advancing at a Rapid Pace

While some advances in influenza diagnostic testing are still in the proof-of-concept stage, they still mark a fantastic step toward a world where you don’t have to worry about flu season. If these advancements continue, you might be able to get your test results in seconds one day.