Health workers prepare to collect swab samples for COVID-19 tests, at an office in Kozhikode on 21 July 2020 | PTI
File photo of health workers preparing to collect swab samples for Covid-19 tests in Kerala | PTI
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New Delhi: Scientists from the Indian Institute of Science Education and Research (IISER) Pune, in collaboration with the city’s BJ Medical College and Sassoon General Hospital, have developed a test that they claim can accurately measure a person’s ability to smell — a tool that could be vital in screening for asymptomatic Covid-19 patients.

Currently, most places conduct a quick temperature check to screen for people who may be carrying Covid infection.

However, several studies have shown that most Covid-positive patients develop no symptoms throughout the course of the disease. This may lead to ‘silent transmissions’.

According to IISER Pune researchers, a smell test may serve as a better indicator to identify people who might be suffering from Covid.

However, the sense of smell is subjective and difficult to quantify.

In their study published in The Lancet’s EClinicalMedicine journal, IISER researchers said they have designed an olfactory-action meter, which can measure how well a person is able to smell.

“Our instrument offers many advantages over the existing clinical methods for assessing olfaction. It delivers odors in a controlled fashion, assesses the olfactory health status in less than 20 minutes of testing, and can innocuously quantify deficits under infective conditions as it has built-in safety precautions to prevent cross-contamination,” said an IISER statement.


Also read: India could have bigger Covid peak next month if mask, social distancing rules aren’t followed


The research method

For this study, the team used 10 different odorous substances at different concentrations. The team connected an olfactory-action meter, a device that delivers odours through different channels with high precision, to 10 different odour reservoirs.

As many as 37 healthy patients were asked to detect the odours at different concentrations. The test was continued till the healthy participants could detect each odour consecutively for two different concentrations. The lower concentration was taken as the threshold for a specific odorant.

The data allowed the team to generate an ‘olfactory function score’ for each individual.

The same test was then conducted among people who had tested positive for Covid. The scores of the two sets of participants were compared.

The team found detectable levels of smell function loss in 82 per cent of asymptomatic Covid carriers. However, only 15 per cent of the same set of patients self-reported a loss of smell.

This indicates that the test developed by the team can detect smell loss even if the patient themselves are not able to perceive it.

“The methods and parameters established by our study can potentially be translated into a sensitive, fast and economical olfaction-based screening assay that can be self-administered by large populations,” said the IISER statement.


Also read: ICMR cut-off for Covid reinfection arbitrary, could lead to missed cases, experts say


 

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