> Updates > Recently, a new Coronavirus was identified as the cause of the severe acute respiratory syndrome (SARS).- In the absence of a specific treatment for SARS, the possibility that vitamin C may show non-specific effects on severe viral respiratory tract infections should be considered.- There are numerous reports indicating that vitamin C may affect the immune system.- Studies in animals found that vitamin C modifies susceptibility to various viral and bacterial infections.- Placebo-controlled trials have shown quite consistently that the duration and severity of common cold episodes are reduced in the vitamin C groups, indicating that viral respiratory infections in humans are affected by vitamin C levels.- There is also evidence indicating that vitamin C may affect pneumonia.-In particular, three controlled trials with human subjects reported a significantly lower incidence of pneumonia in vitamin C-supplemented groups, suggesting that vitamin C may affect susceptibility to lower respiratory tract infections under certain conditions.-The possibility that vitamin C affects severe viral respiratory tract infections would seem to warrant further study, especially in light of the recent SARS epidemic.