Doesn't really specify strongly either way; some excerpts are that UV is less than 1% of transmission, and that shielding is not required/recommended for all QH products. The ones that immediately came to mind are MR16s, although they are available in both sealed and unsealed (exposed envelope) versions.
Having witnessed what happens when a QH lamp explodes, I'd prefer there be at least something there for protection. Some fixtures use a screen instead of glass to prevent shards of 1200F glass from flying all over. Of course, aside from the MR16s in my kitchen most of the QH lamps I use are minimum 500W, up to 2kW. A 25W MR16 may not be as susceptible to a violent explosion like the big boys.
Also, the sealed ones are much easier to replace up high with the suction-cup re-lamping pole :P
