Another example of non-specific protection rendered by unrelated vaccines, i.e., flu shot and the BCG vaccine, boosting innate immunity against SARS.  It is not uncommon that unrelated infectious agents exhibit an anti-inflammatory, broad spectrum, non-specific response which is likely mediated by nitric oxide.  In studies when evaluated for nitric oxide, it was found that BCG among other unrelated infectious agents triggers cytokine-dependent inducible nitric oxide synthase and nitric oxide release by both alveolar macrophages and non-immune cells, including fibroblast and airway epithelial cells, reducing pathogen burden and minimizing an uncontrolled inflammatory response.  Nitric oxide is likely contributing to the protective response observed in this report.  Previous studies showing nitric oxide's role in non-specific, innate immunity are highlighted: www.medpagetoday.com/.../86410