The efficacy of three SARS vaccine candidates was tested in a murine SARS model utilising low-virulence Pp and SARS-CoV coinfection.Vaccinated mice were protected from severe respiratory disease.A high level of IL-6 and on days 2 and 3 after SARS-CoV infection was closely linked to the virus replication and disease severity, suggesting the importance of these cytokines in the lung pathogenicity of SARS-CoV infection. Here, IL6 is linked to severe acute respiratory syndrome.