Blood RNA sequencing was performed on a cohort of adults attending the Emergency Department with suspected infection who had subsequently-confirmed viral, bacterial, or no infection diagnoses. Blood RNA sequencing was performed on a cohort of adults attending the Emergency Department with suspected infection who had subsequently-confirmed viral, bacterial, or no infection diagnoses

The cohort comprised patients recruited between August 2014 - April 2017. It includes patients with bacteremia, positive viral diagnostic test in the context of acute admission and those with no positive microbial diagnostic test, no infection-related ICD-10 diagnostic codes, and no empirical antiviral/antimicrobial treatment >48hrs duration. RNA was subjected to RNA-Sequencing. All patients with definite bacterial or viral infection were used for gene signature discovery. Whole blood was collected at the time of recruitment in Tempus Blood RNA tubes and total RNA was isolated with the TempusTM Spin RNA Isolation Kit (ThermoFisher Scientific) according to the manufacturer’s instructions. RNA samples were stored at −80 °C until further analysis. After additional DNAse treatment, library preparation and sequencing of 30 million 100bp, paired end reads were conducted using the Illumina's TruSeq® RNA Sample Preparation Kit; ribosomal and globin RNA depletion was performed using the Illumina Ribo-Zero Gold kit and HiSeq 4000 at The Wellcome Centre for Human Genetics in Oxford UK.