To wit, small arms fire such as the machine gun or pulse rounds will chip away at your armour (which is really more of a forcefield) until it is depleted at which point a Hit Point is sacrificed to replenish it.
There's some legitimacy to this claim, to wit: having a rapid change in temperature (such as a home with a roaring fire to the freezing midwinter outdoors) can weaken your immune system and make you more susceptible to showing symptoms of the common cold.