Why are health officials so worried about H5N1?
There are several strains of influenza circulating in the world at any given time, and most people have been exposed to the flu and have built up some immunity. What is worrisome about H5N1 is that it is a completely new form of influenza so if it (or a mutated form of the virus) gets a foothold in humans, the consequences could be devastating. The World Health Organization estimates that a pandemic strain of influenza — one to which we have no immunity — could kill between two and 7.4 million people worldwide. (In a “normal” year, the flu kills about 500,000 people.) But some infectious-disease experts have made far more dire predictions, warning of up to 360 million deaths. The last time there was a pandemic form of influenza was the Hong Kong flu in 1968-69. Some experts believe the world is overdue.
