In 2012, Tseng et al. published a seminal paper in PLoS One describing the effects of several SARS-CoV vaccine candidates on subsequent challenge of research animals with SARS virus. Vaccinated mice developed anti-SARS antibodies and were protected from viral infection upon challenge. However, their lung showed a serious type of immunopathology in response to post-vaccinal virus exposure – pulmonary eosinophilic infiltration. The authors cautioned against application of these vaccines in humans.