On-the-spot tests are much in needOctober 5, 2020
India has now become the leading country in terms of COVID-19 spread, reporting the highest daily increases in infections anywhere the world. Present diagnostics in the country mainly rely on polymerase chain reaction (PCR), supplemented by recently introduced antigen detection kits. While PCR remains the gold standard, antigen detection is much faster, cheaper and less labour- intensive. At present, antigen tests are administered by trained professionals, but there is an urgent need to make these technologies home-based, similar to pregnancy tests. A typical antigen test is done by healthcare professionals taking a swab from a person’s nose or throat (several companies are also developing kits for saliva samples). The sample is then mixed with a solution that resuspends the virus and exposes its proteins. This mix is then added to a paper strip which contains an antibody or detector molecule to detect the virus resulting in colour change. These kinds of tests can be performed within 30 minutes and are low-cost. Many home-based antibody detection kits have been in the market, but now, these antigen detection kits may play an important role as they can give early detection even in asymptomatic individuals. Self-detection of COVID-19 may help people to take an informed decision to quarantine themselves and reduce the spread of the virus.
Further research into specific properties of viral proteins, such as spike proteins, may result in novel screening technologies which may emerge soon. Community-based or general population screening without the help of sample collection or processing may help in reduction of infection rates. Currently infrared forehead thermometers are routinely used to measure the temperature of people at several places – referred to as thermal screening. This is prone to several manual errors and is not scalable for a large population. It also poses risks for security personnel. Several other features, such as screening for other symptoms, have been added and artificial intelligence-based tools are under development for automatic screening at public places.
One important novel technology under development is infrared (IR)-based facial scanning for pathogen or viral infections. It is a very well-known fact that IR based sensors have been developed for screening for influenza and several other pathogens. This is a new field emerging as a frontrunner for developing large-scale screening approaches and technologies using near-infrared spectroscopy (NIR). NIR works over a large range of wavelengths and can look for specific wavelengths for pathogens or their constituent proteins or molecules. NIR based detection of oxygenated and deoxygenated haemoglobin has also been practiced. The major advantage of such technologies is that the need for biospecimen collection or processing is completely eliminated, making them the simplest technology to use for large-scale screening. The use of a combination of NIR and multivariate factor-based screening may revolutionise COVID-19 screening. Such technologies are much needed primary screening methods which can lower the cost of diagnostics, reduce the spread of infection and improve economic activities.