Why continued COVID-19 testing matters

There are two main types of test available:  Polymerase chain reaction (PCR) and Antigen (or rapid) tests. Antigen tests are immunoassays that detect the presence of a viral antigen, implicating infection with that virus. They are fast, simple, relatively cheap, and most can be used at the point of care. This is handy for screening– for diners booking a restaurant table, or travelers preparing for a journey, or students and staff testing before entering their school or workplace. But they have a lower sensitivity than PCR tests, meaning there is a chance they can return a false negative result. Therefore, they need to be used in wider conjunction with PCR tests and a patient’s clinical history for diagnosis.¹

In contrast, PCR tests, which detect viral RNA (pieces of the SARS-CoV-2 genetic code), are highly sensitive. This means they can reliably detect even small amounts of SARS-CoV-2 and are unlikely to return a false negative. As well as being the gold standard for diagnosing COVID-19 since the beginning of the pandemic, the higher sensitivity means that the test can catch COVID-19 infection early on in an infection, potentially before a patient is symptomatic (Figure 1).  In the case of a COVID-19 variant, such as omicron, PCR tests have also been proven successful in recognizing the mutated strains of the virus while an antigen test will detect, but cannot identify novel variants.

This ability to catch COVID-19 early is important for limiting the spread of infection, but also may be critical for the successful deployment of new antiviral medicines currently being developed (designed to prevent the virus from penetrating or replicating in the body’s cells), which need to be started within the early stages of infection.

PCR testing is a complex technique and has historically been confined to high-complexity laboratories. However, innovation in microfluidics and optical sensing has led to development of smaller, faster, easier-to-use instruments, such as the QIAstat-Dx, that can be deployed in environments like Emergency Rooms.

QIAstat-Dx in practice

Dr. Benoît Visseaux, a virologist at Bichat hospital in Paris, used to send samples to a lab via pneumatic tube and then wait hours or even days for the results. This meant that until the correct results were received, patients were treated or isolated based only on what doctors suspected was wrong with them, leading to possible mis-diagnosis, wrongly prescribed antibiotics, and whole wards blocked just for one quarantined patient. With the QIAstat-Dx, the lab resides in the ER. The machine is small, simple to use, and users need less than one minute of hands-on time to prepare a sample. It surveys a large number of pathogens and then produces prompt answers on site, exactly where they’re needed.

Fast results are just as crucial in nursing homes and assisted living facilities, where residents are more susceptible to a rapid-spread virus such as COVID-19. “When tests take too long to come back to assisted living facilities or rehabilitation centers, opportunities to improve care are missed – and those patients needlessly suffer,” according to Steve Hoover, Vice President of Laboratory Operations at Mako Medical in the rural community of Henderson, North Carolina. Just as in the ER, a slow turnaround on lab testing can be fatal to a patient, and dangerous to front-line medical workers. This is another perfect example of how QIAstat-Dx plays a vital role in Mako's work sending back swift PCR results to care facilities, halting the rapid spread of infections in an environment where the majority of residents are vulnerable.

What if it isn’t COVID-19?

When a sheriff reported a COVID-19 outbreak in his jail in Northwest Indiana during the early days of the pandemic, the President of Great Lakes Labs, Michelle Volk, had an idea how she could help out in such cases. She converted her lab from a forensics to a testing facility with the help of the QIAstat-Dx and the Respiratory SARS-CoV-2 Panel, which rapidly differentiates the novel coronavirus from 20 other pathogens implicated in respiratory syndromes.

“It’s hugely beneficial to be able to test for that wide range of pathogens,” Volk says. Not only can she identify or rule out COVID-19, but also identify other illnesses.

This protects the people who are crucial to the social structure in times of crisis, because a nurse or doctor isolating at home is one vital worker less on the frontline. Just as a first responder in quarantine is one less fireman or paramedic at the scene of an explosion or an accident.

Dealing with larger sample volume

Rapid test results are key to the continuing cultural and economic life of society. But what about large groups vs. the single patient sample? The London-based Fleet Street Clinic counts film production companies among its clients. These clients needed larger groups tested simultaneously. Serial testing allowed the resumption of shooting on sets that had been initially paralyzed by the pandemic. The firm used the NeuModx system, which is fully automated and can run up to 288 patient samples in 8 hours. The system's available assays span multiple disease areas such as bloodborne viruses, transplant, sexual and reproductive health, and respiratory.

Returning to the office, the classroom or the cinema have not been the only goals in resuming a pre-COVID-19 lifestyle. From the start, taking measures to ensure safe, virus-free travel have been central to governmental COVID-19 policies. Last year, the Thai government installed a lab in the main arrivals terminal at Suvarnabhumi airport to test hundreds of short-stay passengers not required to enter quarantine. They also wanted to control the spread of any infections within the airport itself.

Dr. Rome Buathong, a field epidemiologist at Thailand’s Ministry of Public Health, says that PCR testing was essential "because of its superior sensitivity to antigen tests". Converting the former first-class lounge into a lab equipped with the QIAstat-Dx, Rome and his team also used the highly flexible QIAprep&amp Viral RNA UM Kit, which integrates a two-minute liquid-based sample preparation with a real-time PCR detection, taking less than one hour to deliver a result.

Whether in airports, offices, hospitals, care homes, jails or movie studios, testing has been vital to preventing the spread of the COVID-19 virus, and to helping multiple parts of the community function and hold the social fabric in place.