While the world waits for a vaccine to be developed and approved for use against the COVID-19 virus, the best measure to identify, slow and prevent the spread of the virus is to test.
Large-scale rapid testing of symptomatic patients is essential if the contact-tracing systems now in place across several countries are to work effectively and local outbreaks contained. Since March 2020, the Director General of the WHO has been stressing that countries must “test, test, test” if we are to stop this pandemic. More recently, the London School of Hygiene & Tropical Medicine claimed that large-scale testing and tracing is key to preventing a second wave of COVID-19 and suggested that if at least 50% of symptomatic COVID-19 cases are tested, a second surge of infection could be prevented.
In order to meet this goal, a rapid diagnostic kit is urgently needed. However, an accessible rapid diagnostic test that can accurately and reliably test for COVID-19 is proving to be a challenging request.
Too slow, too expensive or not sensitive enough
Currently, most pandemic-prone diseases, including coronavirus, are diagnosed by polymerase chain reaction (PCR), a molecular technique that identifies the genetic material of the virus and can therefore identify an active infection.
The COVID-19 test currently being distributed by the UK government is a PCR test. A sample is collected in a home or mobile environment such as police stations, care homes or drive-through centres. Alternatively, a postal kit including a swab applied to the nose or throat can be sent to UK homes. The collected samples need to be sent to a designated lab for analysis by specialist laboratory staff in order for the results to be obtained.
While PCR tests can be very accurate, they usually require laboratory equipment and highly trained technicians to operate them. This makes the technology expensive and difficult to scale up and decentralize. Furthermore, the technology does not readily lend itself to providing fast results while still remaining accurate. Efforts are being made to reduce the time required for COVID-19 PCR tests to return their results and Singaporean organisation A*STAR together with MiRXES have recently developed a PCR test that can tell in about three hours whether a person has COVID-19.
Another route for testing COVID-19 involves antigen tests, which detect the presence of viral proteins in a biological sample such as saliva or a nasal swab. Antigen tests can be cheap and often return results in minutes. Rather than performing the analytical steps inside costly dedicated equipment as with the PCR tests, antigen tests build the required analytical steps on a test strip and give a simple yes or no result. However, a challenge with antigen tests is weak signals. Unlike PCR tests where the DNA or RNA sequences are amplified such that only a few copies of the virus are needed to identify it, antigen tests don’t amplify their protein signal so are intrinsically less sensitive, making it difficult for antigen tests to reliably generate a positive result for people who have had the virus.
Despite these hurdles, antigen tests bring several advantages. They don’t require the expensive equipment needed to perform PCR, they don’t require trained specialists to analyse the result and, once developed, are more easily scaled up and manufactured in bulk. This makes antigen tests more easily used as point-of-care tests in hospitals, care centres and potentially even offices and schools. Most importantly, the fast results from antigen tests mean that people who test positive can be isolated quickly before they risk infecting others.
An alternative route for testing COVID-19 involves serological tests. These tests detect the presence of antibodies in individuals who have already contracted the virus and who have developed antibodies to the virus. In order for the test to work, a person needs to have been infected long enough in order for them to develop the antibodies. As such, unlike the PCR and antigen tests which are being used to determine whether someone has an active infection, the focus of serological tests is to determine whether someone has previously been infected with the virus. Gaining an understanding of the proportion of the population that has already been infected with COVID-19 is important for the broader context of monitoring and managing the outbreak.
A new dawn for UK diagnostics
Several UK universities and companies have joined the race to develop a rapid point-of-care diagnostic kit for COVID-19.
UK researchers from Brunel University London, Lancaster University and the University of Surrey have developed a new rapid molecular test that can provide COVID-19 detection in as little as 30 minutes. The hand-held hardware costs as little as £100 with individual swab kits costing around £4 per person. The hardware connects to a smartphone application to display the result. The device is easy to use and the swabs don’t need to be sent to a lab for analysis. The test is capable of performing diagnostics at any location with very minimal training, making it a suitable point-of-care test for deployment in hospitals, care centres and potentially even workplaces for truly widespread and accessible testing.
A partnership between Mologic Ltd, headquartered in Bedford, and UK diagnostic manufacturer BioSure has resulted in the development of a COVID-19 lateral flow rapid diagnostic test. With the help of Liverpool School of Tropical Medicine and St George’s, University of London, the test has been certified with a CE mark and is ready for manufacture and global distribution. The “triple antibody” test provides a result within 10 minutes without the need for special training, electricity or a laboratory meaning it can be used for self-testing at home. The companies are aiming to manufacture the devices with a target price of £1 per device.
The UK has always had a strong diagnostics sector. It is the fifth largest IVD market in Europe and was valued at almost £1 billion according to MedTech Europe. However, the diagnostics industry can sometimes be overshadowed by the quest for new treatments and vaccines. COVID-19 has clearly shown the importance of diagnostics in overcoming this pandemic. The industry must ensure this momentum is not lost once we stop talking about coronavirus testing and ensure the broader conversation on the value of diagnostics on containing possible future pandemics and solving wider healthcare challenges is maintained. Access to fast and reliable diagnostic tests aids in disease prevention or provides early detection to ensure the most effective treatment can be administered, saving healthcare systems time and money. Diagnostic tests already exist that can provide timely diagnosis of asthma, influenza, bowel cancer, heart failure and many other conditions. We have the opportunity now to emerge from this pandemic with an even stronger diagnostics sector that can support healthcare systems beyond this pandemic, improve patient care and, ultimately, save lives.
This blog was written by Tara Fitz Gerald.
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