I should have looked at the 2 models quoted a bit more closely before assuming either were typical backcountry filtering solutions. As it turns out both are somewhat unique to the market (something worth noting).

The Saywer model actually has a .02 micron filter which would put it in that ultrafiltration category the CDC mentioned.

The First Need unit is a bit different, it says it has a .1 micron filter but it could be one of its other stages deal with viruses (its literature didn't specify how exactly viruses were dealt with).

The EPA portion I believe refers to the EPA standards for water filter and purifiers; both companies say their products have been independently tested and have been shown to meet these standards. I found these standards described here.

Since both these products are designed to remove viruses (and therefore marketed as having the ability) they belong in a different class than the filters most of us would find at the local MEC or REI store.