While almost everything about SARS-CoV-2 has been novel, scientists were able to determine early on that children are significantly less affected by the virus (excluding the Delta variant) than their adult and elderly counterparts.
In November 2020, a study from two New York hospitals confirmed that children and adults produce different types and amounts of antibodies in response to the presence of SARS-CoV-2. And now—using breath samples—researchers at the Children’s Hospital of Philadelphia (CHOP) are lending more proof to the idea that the course of infection is significantly different between children and adults.
In a new study published in ACS Infectious Diseases, researchers collected breath samples for metabolite profiling from 26 pediatric patients—11 confirmed positive for COVID-19 and 15 whom tested negative.
For targeted metabolite analysis, the team zeroed in on 84 volatile organic compounds (VOC) that have been previously identified as common human odorants, ones associated with response to viral infection or ones found to be elevated in the breath of adults with COVID-19.
Using 2D gas chromatography and time-of-flight mass spectrometry (TOF-MS), Amalia Berna and colleagues identified six biomarkers that were significantly elevated in the breath of children with SARS-CoV-2 infection: octanal, nonanal, heptanal, decane, tridecane and 2-pentyl furan.
Octanal and heptanal have been recorded at elevated levels in adults with COVID-19. However, the biomarker nonanal seems to be unique to just pediatric infections. Contrastingly, acetone and 2-butanone—abundant biomarkers of SARS-CoV-2 infection in adults—are absent in infected children.
For reproducibility purposes, the researchers then measured the VOCs in breath samples among a different group of 24 children—half of whom tested positive for the virus, half of whom tested negative. According to the study results, the 6 identified pediatric biomarkers can predict infection with 91% sensitivity and 75% specificity.
“Our study highlights the need to include pediatric samples in early discovery efforts to develop new and much needed diagnostics for SARS-CoV-2, in order to identify biomarkers that are shared across all relevant populations,” the team writes in their paper.
As some countries enter another wave of COVID-19, they may come to rely once again on frequent, rapid testing—especially for events that place people in close proximity to one another, such as school, sporting events and concerts. The researchers think their method could enable an easy-to-use SARS-CoV-2 “breathalyzer” based on electronic nose technologies or sensor arrays that would have a turnaround time of minutes and would not strain supply chains, like we have seen in the past.
“Because of ongoing advances in portable, low-cost, field-stable sensor array platforms that may be harnessed for a VOC-based diagnostic, there is enthusiastic industry support that may rapidly translate volatile biomarkers into physical devices for point-of-care testing or screening,” the researchers conclude.
Photo: To collect breath, child places mouthpiece (1) between the lips and exhales completely. Volatiles are transferred from two-way valve (2) to SamplePro FlexFilm sample bag (3). Credit: Amalia Z. Berna, et al. ACS Infectious Diseases Article ASAP. DOI: 10.1021/acsinfecdis.1c00248