I think what H&N was saying was that if the children had already been exposed to H1N1, then they would likely have some immunity to H1N1 - not the seasonal flu.
Sorry - I failed to type a '6'...

There are 6 identified strains of SIV, so whether the children were exposed to H1N1 is a role of the dice, literally.

This is why I don't vaccinate against SIV (or any flu):
1) I'm not in anything close to a high-risk category, so the implications of me falling ill are fairly low.
2) dozens of flu strains go around every year, and the flu vaccines do not cover all of them. You're really rolling the dice to see which strains are coming to your town that season.

However, if I was in a risk category (and I personally don't believe pregnancy is if you're otherwise fit & healthy), I would vaccinate because I'd rather have a prepared immune response to some of the strains than none of the strains. And that includes SIV (H1N1).