A five-minute primer on an issue making headlines Why is Tamiflu in the news? It is believed to be one of the few effective medicines to attack the H5N1 bird-flu virus, which is causing fears of a global pandemic if it mutates into a form that is transmissible between humans. Who makes Tamiflu? It was developed by Gilead Sciences, and Swiss-based Roche Group manufactures the drug. In July, Roche said that in the second quarter of this year sales of the group's products rose 17 per cent and net income reached 3.2 billion Swiss francs ($19.21 billion). In May, Roche said demand for Tamiflu was causing a production bottleneck, with new customers likely to wait for up to two years. Are other drugs effective against H5N1? Relenza, developed by Biota of Australia and licensed to GlaxoSmithKline, is also being stockpiled. What is the price? Tamiflu costs $180 per course of treatment - twice a day for five days - compared with $140 for Relenza. What is Hong Kong doing about the danger of a pandemic? Last month Hong Kong had a stock of 3.7 million anti-flu tablets, mainly Tamiflu. The Centre for Health Protection says it will stockpile both Tamiflu and Relenza and is ordering an additional 16.8 million tablets at a cost of $254 million. With 20 million tablets to be kept in the stockpile, 30 per cent of the population would be covered, which makes it one of the highest rates in the world.