One slip up from a worldwide pandemic.

Do the risks of a lethal flu virus escaping the lab outweigh the benefits of the research, ask and .

Avian flu special: avian flu: are we ready?

On the cover, a Shanghai commuter takes precautions during the 2003 avian influenza outbreak. It is nearly 40 years since the last worldwide influenza pandemic, and though these things don't run to an orderly timetable, many believe that it is only a matter of time — not much time at that — until the next one. This adds to the public health implications of the recent avian influenza outbreaks in Hong Kong in 1997, 1998 and 2002/3, and the continuing spread of avian influenza in poultry populations in Asia.

Infectious disease: Vietnam's war on flu.

Having suffered heavily from avian influenza in 2004, Vietnam might now be brewing the next human flu pandemic. Yet, as Peter Aldhous discovers, local researchers don't have the resources to investigate the risk properly.