New Delhi: The US Food and Drug Administration (FDA) has granted emergency-use authorisation to the world’s first breath test for Covid-19 that is expected to give results in less than three minutes.
The test, which uses an instrument about the size of a piece of carry-on luggage — baggage that is typically 9x14x22 inches — can be conducted anywhere, from hospitals to mobile testing sites.
Called the InspectIR Covid-19 Breathalyzer test, it detects chemical compounds in breath samples associated with SARS-CoV-2 infection. It needs to be performed by a qualified and trained operator under the supervision of a licensed healthcare provider.
InspectIR, the company that produced the test, partnered with Guido Verbeck from the University of North Texas to develop the device, the FDA said in a press release Thursday
The test was validated in a “large study of 2,409 individuals”, including those with and without symptoms, the FDA added. The study, the release said, showed the test as having 91.2 per cent sensitivity — that is, it correctly identified positive samples 91.2 per cent of the time. Its specificity — the percentage of negative samples the test correctly identified — was 99.3 per cent.
The study is also said to have shown that, in a population with only 4.2 per cent of individuals who are positive for the virus, the test had a negative predictive value of 99.6 per cent. This means that people who receive a negative test result are likely truly negative in areas of low disease prevalence.
For comparison, the Rapid Antigen Tests (RAT), which show results in 15 minutes, have a higher tendency for false negatives — meaning that those with symptoms need to undergo a confirmatory RT-PCR test if the RAT yields negative results.
The InspectIR Covid-19 Breathalyzer uses a technique called gas chromatography gas mass-spectrometry (GC-MS). This method separates components of chemical mixtures and rapidly identifies five Volatile Organic Compounds (VOCs) in the ketone and aldehyde associated with SARS-CoV-2 infection in the exhaled breath.
When the test detects the presence of VOC markers of SARS-CoV-2, it shows a positive result. However, a positive result will need to be confirmed with a molecular test, such as RT-PCR. Molecular tests are used to detect viral infections by amplifying bits of viral RNA.
However, the FDA warned that negative results must be taken in the context of a person’s recent exposures, history, and the presence of clinical signs and symptoms consistent with Covid-19 before the SARS-CoV-2 infection is ruled out.
Negative results “do not rule out SARS-CoV-2 infection and should not be used as the sole basis for treatment or patient management decisions, including infection control decisions”.
The test was originally devised to help detect hundreds of volatile organic compounds on the breath, such as illicit drugs.
Although InspectIR has not revealed the specific five volatile organic compounds its device detects, studies have shown that Covid patients have higher levels of propanol and lower levels of acetone in their breath.
InspectIR expects to be able to produce approximately 100 instruments a week. Each instrument can evaluate approximately 160 samples a day. At this level of production, testing capacity using the InspectIR COVID-19 Breathalyzer is expected to increase by approximately 64,000 samples a month, the US FDA said.
(Edited by Uttara Ramaswamy)