text: Metabolomics in the Diagnosis and Prognosis of COVID 19 Coronavirus disease 2019 COVID 19 pandemic triggered an unprecedented global effort in developing rapid and inexpensive diagnostic and prognostic tools Since the genome of SARS CoV 2 was uncovered detection of viral RNA by RT qPCR has played the most significant role in preventing the spread of the virus through early detection and tracing of suspected COVID 19 cases and through screening of at risk population However a large number of alternative test methods based on SARS CoV 2 RNA or proteins or host factors associated with SARS CoV 2 infection have been developed and evaluated The application of metabolomics in infectious disease diagnostics is an evolving area of science that was boosted by the urgency of COVID 19 pandemic Metabolomics approaches that rely on the analysis of volatile organic compounds exhaled by COVID 19 patients hold promise for applications in a large scale screening of population in point of care POC setting On the other hand successful application of mass spectrometry to detect specific spectral signatures associated with COVID 19 in nasopharyngeal swab specimens may significantly save the cost and turnaround time of COVID 19 testing in the diagnostic microbiology and virology laboratories Active research is also ongoing on the discovery of potential metabolomics based prognostic markers for the disease that can be applied to serum or plasma specimens Several metabolic pathways related to amino acid lipid and energy metabolism were found to be affected by severe disease with COVID 19 In particular tryptophan metabolism via the kynurenine pathway were persistently dysregulated in several independent studies suggesting the roles of several metabolites of this pathway such as tryptophan kynurenine and 3 hydroxykynurenine as potential prognostic markers of the disease However standardization of the test methods and large scale clinical validation are necessary before these tests can be applied in a clinical setting With rapidly expanding data on the metabolic profiles of COVID 19 patients with varying degrees of severity it is likely that metabolomics will play an important role in near future in predicting the outcome of the disease with a greater degree of certainty 