BRAVE little Lau Wan-yi appears to have won her fight for life, but it could be two years before doctors can give her the all-clear. Just six months ago, five-year-old Wan-yi was diagnosed as having leukaemia and since then has spent her days in and out of operating theatres and hospital wards. The pain and the worry came to an end when she was released from the Prince of Wales hospital at Sha Tin and allowed to go home. Wan-yi was one of the lucky ones because her release from hospital was made possible by her younger sister, who donated bone marrow for a transplant operation. Other sufferers remain in hospital desperately waiting for a bone marrow match from donors listed in Hong Kong's bone marrow registry. The registry at the Queen Mary Hospital and the Paediatric Bone Marrow Transplant Unit at the Prince of Wales Hospital are the beneficiaries of this year's Operation Santa Claus, conducted by RTHK and the South China Morning Post. Prince of Wales bone marrow transplant specialist Dr Li Chi-kong said that relatives usually provided the best chance for people needing bone marrow. He said there was a 25 per cent chance that relatives would have suitable bone marrow. If a family member cannot provide a match-up, doctors are forced to look to the bone marrow registry and hope a match can be found. About 200,000 people are enrolled as donors. Dr Li said that if a transplant was made and there was no rejection, the patient would continue to undergo regular checkups for two years before they could be given the all-clear. ''Wan-yi was diagnosed as being a high-risk patient and we opted to go for a transplant straight away. It seems to have been successful,'' Dr Li said. ''It was five weeks ago today that the transplant was actually made and things have gone well since then. ''It gives the whole staff a really good feeling when we see a patient leave who looks like they will go on to lead a normal life. ''We only treat children in our transplant centre, which is more of a challenge than treating adults, but also more rewarding.'' Operation Santa Claus aims to raise enough money to boost the number of donors in the foundation registry, buy more equipment for transplants and finance a halfway house for recovering patients.