Breath samples better than nasal swabs to detect Covid-19, Irish research shows

Higher rate of viral detection in breath samples as swabs give 30% false negatives 
Breath samples better than nasal swabs to detect Covid-19, Irish research shows

A new study published by researchers at the Royal College of Surgeons of Ireland, using breath samples, detected Covid-19 in 14 out of 15 patients who clinically appeared to have Covid-19 but whose swabs were negative for the virus.

Breath samples have been shown to be more reliable than nasal swabs for detecting Covid-19, a new study published by researchers at the Royal College of Surgeons of Ireland (RSCI) has shown.

The research, published in the British Medical Journal publication Thorax, is among the first studies globally to investigate the potential use of breath samples to detect coronavirus.

Professor Bryan Hennessy, one of the lead researchers involved, said the findings were “quite dramatic” and described the research as “cutting edge”.

Standard testing for Covid-19 at present relies on swabs taken from the nose, which are then tested for the virus using reverse transcriptase polymerase chain reaction (PCR) tests.

While considered the gold standard, the current testing regime can yield a high rate of false negatives and fail to detect the virus, which commonly affects the respiratory system.

“False negatives from swabs are quite high and that has been shown internationally to be around 30%. If you take 100 people with Covid-19 approximately one third of them will swab negative,” Prof Hennessy said.

Breath samples, however, contain droplets from the lower respiratory system and for that reason may improve detection of the virus.

The RSCI researchers, who previously investigated the potential for detecting lung cancer in breath samples, set their sights on testing breath samples for Covid-19. They took samples from 40 patients who had tested either positive or negative for Covid-19 using nasal swabs, including some who tested negative but showed clinical symptoms for viral infection.

Breath samples were taken by patients blowing into a tube where the breath turned into a liquid that was then tested using the standard PCR test for Covid-19.

Their preliminary findings, Prof Hennessy said, showed a much higher rate of viral detection in breath samples compared to standard nasal swabs.

“We had 15 patients who clinically appeared to have Covid-19 but whose swabs were negative for the virus. We collected breath samples from them and we were able to detect Covid-19 in 14 of these 15 patients,” Prof Hennessy said.

“The percentages were so high to suggest that breath clearly has the potential to outperform nasal swabbing,” he said.

It was too early to say if breath samples could replace nasal swabs in standard testing for the virus, he said, and it will require further research.

“We feel that breath could represent a superior way to detect Covid-19 and this preliminary study suggests that breath is better than standard nasal swabs and we will continue to progress and develop research in this area,” he said.

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