Can the Electronic Nose Smell COVID-19 Antibodies?

Corona Virus Disease (COVID-19), spread worldwide and has become an emergency of major international concern. In March 2020, the WHO declared the COVID-19 outbreak a global pandemic. Accurate and fast diagnosis is crucial in managing the pandemic. Current diagnostic approaches raise several difficulties: they are time-consuming, expensive, invasive, and most important lacking high sensitivity. The gold standard diagnostic test for COVID-19, reverse transcription polymerase chain reaction (RT-PCR), is highly dependent on adequate deep sampling of the swab in the naso- and oropharynx. A new diagnostic test that can correctly and rapidly identify infected patients and asymptomatic carriers is urgently required to prevent further virus transmission and thus reduce mortality rates. Aim: This proof-of-principle study aims to investigate if an electronic nose (Aeonose) can distinguish individuals with antibodies from individuals without antibodies against COVID-19 based on analysis of volatile organic compounds (VOCs). Methods: between April and July 2020, persons undergoing RT-PCR and a serology test for COVID-19 were recruited at Maastricht UMC+ for breath analysis. All participants had to breathe through the Aeonose for five consecutive minutes. The VOC pattern in their exhaled breath was then linked to the matching RT-PCR and serological test results.

Participants where included if an oropharyngeal and nasopharyngeal swab was collected for RT-PCR and serology testing had been performed, or if participants have had a confirmed COVID-19 diagnosis in the previous days or weeks with an indication for re-testing via PCR and serology testing at the moment of inclusion

All participants breathed through the Aeonose for five minutes. This device contains metal-oxide sensors that change in conductivity upon reaction with VOCs in exhaled breath. These conductivity changes are input data for machine-learning and used for pattern recognition. A nose clip was placed on the nose of each participant to avoid entry of non-filtered air in the device. Before measuring, the Aeonose was flushed with room air, guided through a carbon filter as well. During each measurement, a video was displayed to distract the participant and to reduce the chance of hyperventilation. Failed breath tests were excluded from analysis; the reason for failure was documented. Four similar Aeonose devices were used for breath analysis. A full-measurement procedure required sixteen minutes.

Ability of the electronic nose (Aeonose) to distinguish individuals with antibodies from individuals without antibodies against COVID-19 based on analysis of volatile organic compounds (VOCs).

Inclusion Criteria: Participants of whom an oropharyngeal and nasopharyngeal swab was collected for RT-PCR and on whom serology testing for the detection of antibodies was performed. Exclusion Criteria: Participants who where experiencing dyspnea or needed supplemental oxygen.

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