The treatment, which has a 50pc success rate, is derived from other victims' blood A serum drawn from the blood of recovered Sars victims has cured more than 10 patients who failed to respond to standard anti-viral treatment, doctors announced yesterday. The findings from the Prince of Wales Hospital are based on the first batch of 20 patients who were given the serum. The patients had initially received a combination of Ribavirin and steroids - the standard treatment adopted by the Hospital Authority to deal with severe acute respiratory syndrome (Sars) - but showed no progress. More than half of the patients in the study have recovered and been discharged, according to Gregory Cheng, associate professor of the department of medicine and therapeutics at the Chinese University. The rest showed no significant improvement and remain in hospital. The university has started using the serum as a 'second-line' treatment on another batch of about 50 patients who have also failed to respond to Ribavirin and steroids. Official data shows about one in 10 Sars patients do not respond to the standard anti-viral treatment. Professor Cheng said patients who responded to the new serum had shown 'dramatic improvement' one or two days after they were treated. The professor said the findings were encouraging and the new treatment had not shown any side-effects so far. He said the serum would be more effective if used on patients in the second week of symptoms, which he categorised as the earlier stage of Sars. However, Professor Cheng admitted that further research was needed to determine whether the serum should be extensively used as the standard second-line treatment for Sars in all public hospitals - or even to replace Ribavirin and steroids. That treatment carries serious side-effects, including possible damage to the liver, heart and blood. It can also cause deformities in unborn children. 'We need to tell the public that we are only at an experimental stage of using this serum for treating Sars. At this stage, we do not have enough data to claim that the serum is the best option above other alternative treatments, such as protease inhibitor,' Professor Cheng said, referring to another second-line treatment. 'The serum is extracted from the blood of Sars patients who have recovered, so we need donors to maintain the supply. 'We also need to make sure their serum contains the antibody of the coronavirus [which is the main virus that causes Sars]. Also, not all the serum can be used, especially the serum from patients who have underlying diseases such as hepatitis,' he explained. Professor Cheng - who contracted the disease in March but has since recovered - was among the 50 or so serum donors. He said the supply was 'just enough' for the Prince of Wales Hospital and he hoped that other patients could donate their serum. 'But we still have the last resort - which is for my colleagues who have also come down with the virus to donate their serum,' Professor Cheng said. Serum is obtained from patients who have developed antibodies in their blood after recovering from Sars. Each patient can donate about 800ml of serum - enough to treat about five patients. Separately, Liu Shao-haei, senior executive manager (Professional Services) of the Hospital Authority said the authority was open to alternative treatments for treating Sars.