A method for determining an indicator used in assessing a likelihood of a subject having a presence or absence of virus associated systemic inflammatory response syndrome (VaSIRS), the method comprising: determining a pair of biomarker values, each biomarker value being a value that is measured or derived for at least one corresponding VaSIRS biomarker in a sample taken from the subject and that is at least partially indicative of a level of the VaSIRS biomarker in the sample, wherein biomarker values are measured or derived for a Group B VaSIRS biomarker and for a Group C VaSIRS biomarker to obtain the pair of biomarker values, wherein the Group B VaSIRS biomarker is an expression product of ISG15, and the Group C VaSIRS biomarker is an expression product of IL16, or wherein biomarker values are measured or derived for a Group D VaSIRS biomarker and for a Group E VaSIRS biomarker to obtain the pair of biomarker values, wherein the Group D VaSIRS biomarker is an expression product of OASL, and the Group E VaSIRS biomarker is an expression product of CD97; determining a derived biomarker value using the pair of biomarker values, the derived biomarker value being indicative of a ratio of concentrations of the VaSIRS biomarkers; and determining the indicator using the derived biomarker value, wherein the subject has at least one clinical sign of SIRS and the at least one VaSIRS biomarker is not a biomarker of any of: bacterium associated SIRS, autoimmune disease associated SIRS, cancer associated SIRS and trauma associated SIRS. determining a pair of biomarker values, each biomarker value being a value that is measured or derived for at least one corresponding VaSIRS biomarker in a sample taken from the subject and that is at least partially indicative of a level of the VaSIRS biomarker in the sample, wherein biomarker values are measured or derived for a Group B VaSIRS biomarker and for a Group C VaSIRS biomarker to obtain the pair of biomarker values, wherein the Group B VaSIRS biomarker is an expression product of ISG15, and the Group C VaSIRS biomarker is an expression product of IL16, or wherein biomarker values are measured or derived for a Group D VaSIRS biomarker and for a Group E VaSIRS biomarker to obtain the pair of biomarker values, wherein the Group D VaSIRS biomarker is an expression product of OASL, and the Group E VaSIRS biomarker is an expression product of CD97; wherein biomarker values are measured or derived for a Group B VaSIRS biomarker and for a Group C VaSIRS biomarker to obtain the pair of biomarker values, wherein the Group B VaSIRS biomarker is an expression product of ISG15, and the Group C VaSIRS biomarker is an expression product of IL16, or wherein biomarker values are measured or derived for a Group D VaSIRS biomarker and for a Group E VaSIRS biomarker to obtain the pair of biomarker values, wherein the Group D VaSIRS biomarker is an expression product of OASL, and the Group E VaSIRS biomarker is an expression product of CD97; determining a derived biomarker value using the pair of biomarker values, the derived biomarker value being indicative of a ratio of concentrations of the VaSIRS biomarkers; and determining the indicator using the derived biomarker value, wherein the subject has at least one clinical sign of SIRS and the at least one VaSIRS biomarker is not a biomarker of any of: bacterium associated SIRS, autoimmune disease associated SIRS, cancer associated SIRS and trauma associated SIRS.