While our attention has been focused on the tsunami disaster, bird flu has been spreading in Vietnam. Between December and last week, seven people have died of the disease in southern Vietnam, enough to make the experts sound the alarm. Perhaps more significantly, cases have appeared in the north of Vietnam - both in humans and poultry. And one case, a 43-year-old man, hadn't had obvious contact with chickens. We've had these warnings before - this time last year there were a lot of worried faces at the World Health Organisation (WHO) in Geneva, the Centres for Disease Control in the US, and in health departments in Vietnam, Thailand and, of course, in Hong Kong. But the feared pandemic didn't happen. Will this be something that happens year after year: the bird flu arriving with the cooler weather, wiping out poultry flocks, infecting some people then burning out or hiding in some North American wild ducks, only to return next winter? Dr Klaus Stohr, head of communicable diseases for the WHO, says this year is a turning point for bird flu. He recently told the BBC that he believes that the infection could either make the genetic jump needed to become a truly human disease this year, or may simply stay a disease of birds that occasionally infects humans. The problem is that no-one - not even the scientists racing to find out more about this disease - knows what the last step involves. What do you and I, the people living in bird flu territory, need to know? Here, in summary, is what we know so far. In its present form, bird flu is a highly lethal disease that has killed most people infected by it - about 70 per cent. Not everyone gets infected during a flu epidemic, but a high proportion do. We could be looking at millions of deaths in Hong Kong alone. So, is there anything we can do to protect ourselves? Vaccination is the most effective, but we're still waiting for production of the vaccine. There are also anti-viral treatments that are effective against normal human flu and these are being stockpiled by governments, including our own. Realistically, though, there won't be enough to go around. The first people to be treated will be health staff and those considered vital to keeping the city working. Should this epidemic catch us unawares and spread quickly through the population, private doctors will run out of anti-flu medication quickly. However, using it on the right people when the bird flu first appears may slow its spread and give us time to establish effective quarantine measures.