Early suppression of H1N1 with antivirals is crucial, When this flu is bad, it's very bad.

"Either you're off work a few days, or you go to hospital, often to the intensive care unit. There's no middle ground."

In the southern hemisphere, 15 to 33 per cent of hospitalised cases went to ICU in the past two months. "That's very high for flu," ... "When this flu is bad, it's very bad."

In these cases the virus rapidly destroys the lungs' alveoli, where gas transfer occurs, often causing acute respiratory distress syndrome (ARDS), which usually kills in half of all cases. ...  found that this past winter in Mauritius and New Caledonia, H1N1 caused ARDS 100 times as often as ordinary flu.

The direct viral damage inflicted on the lungs by severe H1N1 contrasts with SARS and bird flu, whose impact is mainly due to a runaway, body-wide immune response, ... This means early suppression of H1N1 with antivirals is crucial, which in turn requires spotting cases fast.

Who will get severe H1N1? Kumar is coordinating a multi-hospital study of severe H1N1 to find out, .. results suggest severity is linked to HLA, a genetic variation in immune systems. This could be why flu is worse in some ethnic groups.

(194 words, New Scientist max. 200)