Board Thread:Warhammer 40k General Discussion/@comment-203.134.114.240-20130706042929/@comment-3258762-20130715131430

What is the same for all energy shields is that they react to high-velocity objects such as bullets or even a sword-thrust. However, they have to let in slow moving and stationary objects, as well as miniature bacteria so as not to slow down the thing they are shielding.

In other words: Energy Shields offer no protection to biological weaponry.