Understanding the host viral interaction at the nasal mucosa, the primary site of SARSCoV2 infection, may provide important insights into COVID19 pathogenesis. Here, we studied nasal and systemic immune parameters in comprehensively characterised patients hospitalised with suspected or confirmed COVID19, and healthy community controls. PCR confirmed COVID19 participants were more likely to receive dexamethasone and a betalactam antibiotic, and more likely to survive to hospital discharge than PCR negative/IgG+ and PCR negative/IgG- participants. PCR negative/IgG+ participants exhibited a nasal and systemic cytokine signature analogous to PCR confirmed COVID19 participants, but had an increased propensity for Staphylococcus aureus and Streptococcus pneumoniae colonisation. The nasal immune signature in PCR negative/IgG+ and PCR confirmed COVID19 participants was distinct and predominated by chemokines and neutrophils. These findings demonstrate that severe COVID19 is associated with inflammatory chemokine and neutrophil predominance in the nasal mucosa, and that PCR negative/IgG+ individuals with high COVID19 clinical suspicion have inflammatory profiles analogous to PCR confirmed disease.