WHO is worried about a 2nd wave of Swine Flu

I was just reading this article www.abc.net.au…

It says the WHO is worried about a 2nd wave.

“The world is now at the start of the 2009 influenza pandemic. Countries where outbreaks appear to have peaked should prepare for a second wave of infection,” she said.

Something interesting i read about the Spanish Flu was that those who got sick in the first wave and survived where immune to the 2nd wave which was much worse.

So the second wave began and flu quickly spread around the world again.[41] It was the same flu, in that those who recovered from first-wave infections were immune, but it was far more deadly, and the most vulnerable people were those like the soldiers in the trenches—young, otherwise healthy, adults.[42] Consequently, during modern pandemics, health officials pay attention when the virus reaches places with social upheaval, looking for deadlier strains of the virus.