City inventor proposes smell test to track unidentified Covid-19 patients

With more people moving around, authorities have a challenge in tracking down previously unidentified Covid-19 patients.

But a city-based inventor has proposed a nosy solution.

Google mobility data shows that trips to supermarkets and the use of public transport has climbed back up close to the pre-pandemic levels. However, the ability of the government’s Covid-19 surveillance mechanism to identify cases in real-time is limited.

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Thermal guns cannot identify asymptomatic Covid-19 sufferers who do not have a fever and RT-PCR testing takes days to deliver a result.

That was when inventor Vijay Kumar Dhuler, a multiple patent holder, said he struck upon the idea of using the sense of smell to track down Covid-19 patients in high-transit public spaces.

A scientific study on anosmia (loss of smell) and hyposmia (reduced ability to smell) among Covid-19 patients determined that 80% suffered from this problem.

“This loss takes place early on during the infection period,” explained Dr Shannon Olsson, a chemical ecologist with the National Centre of Biological Sciences (NCBS),  who weighed in on the matter of smell loss among Covid-19 sufferers as an independent expert.

Dr Shannon pointed to a recently published worldwide study of 25,620 individuals aged 19 or above who had a respiratory illness or suspicion within the past two weeks, which suggested that “Covid-19 is more strongly associated with chemosensory than with non-chemosensory symptoms, including fever, cough and shortness of breath”. 

That study, in which Dr Shannon is credited as a byline author, reported that smell loss during the illness was the “best predictor of Covid-19 in both single and cumulative logistic feature models”.

A study at the Akash Medical Institute in Devanahalli with 40 walk-in individuals, found most who subsequently tested positive for Covid-19, failed the smell test. The subjects ranged in the age group of 27 to 71. Eighteen were men.

“To pass the test, they had to identify two consecutive tests,” he said, adding that common smells such as eucalyptus oil, vinegar, rose water, coconut oil, dettol and mint solution were used.

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“The smells were randomised to prevent participants from cheating,” Dhuler said.

Dr Kailash N, medical superintendent at Akash, added that: “In our experience, most Covid-19 patients lose their sense of smell,” he said.

Data on 30 test subjects with Covid-19, shared with DH, showed that the nine subjects who passed the test had contracted the disease two weeks before or after. Those who failed had usually contracted it under 14 days.

“Their sense of smell had either been lost or reduced,” Dhuler added.

Dr Shannon cautioned, however, that smell tests could not supplant traditional testing methods. Dhuler said his invention falls in the region between thermal guns and RT-PCR testing.