That could also be spits, blood, or any biological material, or sweat from the infected touching you (as far as we know, virus is in every parts of the body). Skin contact would do. So it is not really limitative. And actually, I know that pretty well, bacteriology/virology and pharmaceuticals are some of the things I make a living from.
So we are d'accord then on this matter

Other chemical protections would not work (as their rating is so inferior to penetration).
Yes. Chemical Protection is another armor addon, and it would be reduced by the Penetration of the virus.
In my opinion, the Chemical Seal however (which is, in any case, only available for full body armor, like MilSpec, e.g.) does exactly the same as described under the EE Suit's entry.
Unless you do the same for other strains, that would not really stand in the logic of the game, that state that a strain is virulent intermetatypes (only effects changing). Unless you had more explanations.
I do

Personal preference and a weak interpretation of the line "Note that a character can only be infected by an HMHVV strain that targets their particular metatype—attempts to infect characters of a different metavariant automatically fail, though the victim may become an unwitting carrier" (Runner's Companion, p. 82).
I know that this isn't meant this way, but that's how I run it

But why not using them as they are. Do you think bounties are so high for the only sake of them being easy prey not dangerous to deal with?
When it comes to ghouls, it is mostly because of numbers and flaws like this one.
I really don't think that was broken from the start. HMHVV is done to be the bogeyman of viruses. Not your common flu. At least, for me, and in fluff. Yeah, it can feel dangerous. Sometimes, players should not need to meet a dragon, an IE or an AI to feel like a B52 load of drek carpet bombed the fan. There are "smaller" things (literaly or not) which should be a threat as well.
Because as they are, they are not a mere threat to player characters. If you ever use the virus (and let's admit it, feral ghouls are really nice opponents ... not too many moral questions, just survival, conveniently stupid and really horrible), it will simply kill every player character or turn them into ghouls. There is no other outcome. They may survive if you let them use hand of god and burn edge, but they will end up as a ghoul invariably.
Here's the math, with a Body-maxed troll:
A troll with Body 11+Suprathyroid gland+pathogenic resistance+nephritic screen 4 rolls 17 dice (penetration included) and has to beat a target number of 8, for just the first test of ten.
Why doesn't he use O-cells, Zeta-Interferon or antivirals you ask? Because they don't work. RC states very explicitly on p. 82 that no "inoculations or antiviral agent has been developed which provides any bonus or protection against any species of HMHVV". Thus, O-cell nanites, which use existing databases for their wondrous workings don't work either.
The only thing that works is a mage who casts cure disease on a high power level, to add dice to this test (7, with 7 successes is a nice number for this troll here).
To have a decent chance of beating the odds, you need to have 30 dice in a test that's basically only body (remember, protective stuff gets reduced by 6, so to reach the 24 dice for 8 hits, you need to have 30 in the first place).
You need to roll
at least 10 tests. If you fail
1! of these tests by even 1 hit, congratulations, you're now a ghoul. But at least you saved some essence and didn't die ... if that's preferable to dying, that is.
And how many PCs at your table are that optimized troll?

No, thanks. I prefer threats that my players have a chance of more than a snowflake in hell to survive.
