Monday, March 4, 2024

The Sound of Coronavirus

New breakthrough technologies have been found by Israeli scientists to initially test for the virus while avoiding going to a lab. These include testing breath, saliva and voice samples

By Dr K K Aggarwal

Testing is a critical part of the “test, trace and isolate” strategy to contain Covid-19. But an end seems nowhere in sight. Cases continue to rise globally including in India. The gold standard test for the diagnosis of the SARS-CoV-2 virus is RT-PCR. Specimens used for the test are nasopharyngeal or oropharyngeal swabs. However, there are some drawbacks associated with their use. Shortage of skilled staff and/or good quality collection kits or viral transport medium, high costs, sampling errors (leading to false-negative results), patient fear and anxiety are some of them. Healthcare workers are also at great risk of infection due to the production of aerosols during the sampling.


Hence, scientists the world over are engaged in research to develop economical alternatives to rapidly and accurately diagnose cases of Covid-19. Some of these tests are:

  • Saliva test: PCR testing on saliva has recently been suggested as a convenient and cost-effective alternative to RT-PCR to detect the SARS-CoV-2 virus. Use of saliva-based testing offers several advantages—collection is easy and can be done with minimum discomfort to the patient during sampling; it is non-invasive and does not need a skilled healthcare worker to collect, can be done at home by people themselves without travelling to a hospital or testing lab, minimises the risk of cross-infection and reduces the use of PPEs and swabs, especially where there is a shortage. It may particularly be useful in children where a nasal swab may be difficult to obtain (deviated septum) or those who need to undergo repeated tests.

However, saliva tests may be less sensitive in detecting Covid-19. Preliminary data from a meta-analysis of trials found 91 percent sensitivity for saliva tests and 98 percent for nasopharyngeal swab tests in previously confirmed infected patients. This means that saliva may have lower concentrations of the virus compared to swabs.

  • Social engineering: This screening is cheap and can be done at home by everybody. It involves checking a person at the entry of the house or the office with five basic things. The person is first offered a welcome dish of jaggery to eat and if he can taste the sweetness, it means he does not have loss of taste. Then he is offered a rose and if he can smell it, it means there is no loss of smell. After that the temperature is checked and SpO2 (blood oxygen saturation) levels after walking. If these are normal, then the strength of the patient’s hand grip is seen and if that too is normal, then it means he is neither asymptomatic nor symptomatic at that particular time.
  • Voice-based analysis: We can know from the voice if a person has a cold. Doctors have for long relied on the sounds of heart beats, respiration and bowel to diagnose diseases. They have used the quintessential signature tool of the doctor—the stethoscope—to do this. Now the smartphone too can be used to screen patients for Covid-19. The use of sound to detect Covid-19 infection is an upcoming technology.

Researchers from Israel are working to use artificial intelligence to analyse the voice of a person to see if he has the infection. The technology will correlate the voice with the symptoms of Covid-19 and issue an alert. If available, it would be a contact-free, non-invasive screening method. Since it would be available on a smartphone, it can be self-administered and should not take longer than a few minutes. But this would only be a screening method and not a diagnostic tool, so it would not be a substitute for confirmatory laboratory tests. Moreover, its reliability as a screening tool also needs to be tested. It seems to be an exciting prospect, but time will tell.

  • Virus detectors: These use radio waves on a breath sample and work like a breath analyser. One needs to breathe into a tube which is then put into a machine which uses terahertz radio frequencies and an algorithm to see if the virus is present. It generates a result within 60 seconds. Individuals perform the test by taking a deep breath and then exhaling into a tube three times. The presence of the coronavirus within the exhaled breath aerosols is determined based on recognition of its spectral signature. In addition to the benefit of providing an immediate result and avoiding any laboratory processing, the test eliminates the need for skilled individuals to obtain the sample and swabs, which have been in limited supply in some areas.

According to one of the researchers, the breathalyser test may also detect the virus within the first four days after initial exposure. This is the window of time when results from polymerase chain reaction testing may be inaccurate. The developers believe that by identifying people who are not carrying the SARS-CoV-2 virus, the test will allow workers to return to their jobs and thereby assist in mobilising the economy. They describe the breathalyser test as “the new thermometer”.

Read Also: Covid and Legislation

An Israeli company which is developing the breathalyser test has called it a “front line” tool that can help restore a sense of normality during the pandemic. NanoScent, the firm making the test kits, said an extensive trial in Israel for the presence of live virus delivered results with 85 percent accuracy, and the product could receive regulatory approval within months. Chief Executive Officer Oren Gavriely reportedly said that the breathalyser would not replace lab tests but was a mass screening tool that could help people gain “the confidence to go back and act as normal”.

  • Using a watch: Many digital watch companies are also trying to assimilate the measurements of temperature, heart rate and SpO2 monitor in smart watches or smart wrist bands to pick up early cases.

Necessity is the mother of invention here.

—The writer is President, Confederation of Medical Associations in Asia and Oceania, and former National President, IMA

Lead picture: YouTube


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