Zombie/28 Days Later/Crossed Scenarios

[The Dark]

I haven't seen that one but I'll check that one out.

This one yes

That's the one. The chapters are Necromantic Zombies, Voodoo Zombies, Nazi Zombies, Revenants, Atomic Zombies, Viral Zombies, Zombie Masters, Viral Hounds and Other Zombified Animals, Zombie Hunters, Zombie Hunter Weapons and Equipment, and Zombie Hunter Tactics.



As far as melee weapons go, BTRC's More Guns! adds 9 thrown weapons, 49 melee weapons, and about 20 improvised weapons statted out for T2K (along with providing enough information to allow for conversions between T2K and TimeLords, Corps, Torg, MegaTraveller, Cyberpunk, GURPS, and HERO; since a conversion document exists to convert Torg/MasterSystem to WEG D6, that can be converted as well).

[DocFirefly]

I'll always throw in a Pitch for Savage Worlds. It's flexible enough to cover everything from meat cleavers to chainsaws, as well as all modern military weapons.

[Enfield]

That's the one. The chapters are Necromantic Zombies, Voodoo Zombies, Nazi Zombies, Revenants, Atomic Zombies, Viral Zombies, Zombie Masters, Viral Hounds and Other Zombified Animals, Zombie Hunters, Zombie Hunter Weapons and Equipment, and Zombie Hunter Tactics.



As far as melee weapons go, BTRC's More Guns! adds 9 thrown weapons, 49 melee weapons, and about 20 improvised weapons statted out for T2K (along with providing enough information to allow for conversions between T2K and TimeLords, Corps, Torg, MegaTraveller, Cyberpunk, GURPS, and HERO; since a conversion document exists to convert Torg/MasterSystem to WEG D6, that can be converted as well).

Thanks for the tips. I'll try to see if I can find a copy, but if not I may do some rules juggling with Call of Cthulhu, whose supplements have a number of melee weapons. (For instance I have the Dark Ages and Cthulhu Invictus setting books.)

[Enfield]

I'll always throw in a Pitch for Savage Worlds. It's flexible enough to cover everything from meat cleavers to chainsaws, as well as all modern military weapons.

Thank you. BTW, @all taking part here--any thoughts on my infection process in the OP

[The Dark]

Thank you. BTW, @all taking part here--any thoughts on my infection process in the OP

I like it. Just for the heck of it, I rewrote it like a disease from the v2.2 rule book with some fill-in-the-blanks guesses for things that weren't mentioned in the original write-up:

S1R1
Transmission: Contact with infected fluids (saliva), able to survive on surfaces for ~24 hours. Infection Number 5.
Symptoms:
Phase I: Fatigue, dizziness, fever, sneezing
Phase II: Delirium, amnesia, muscle spasms, dementia
Phase III: Hallucination, violent psychosis
Diagnosis: Formidable
Misdiagnosed As: Influenza or minor disease
Treatment: Relief of symptoms (+2), Antibiotic- (+3) or Antibiotic+/- (+1). Treatment effective only in Phase I (or during Incubation). If multiple antibiotic types used, count only the best one.
Course of the Disease:
Incubation: 1 day
Phase I: 1d3 days
Phase II: 7 days minus Phase I
Phase III: 90 days
Base Recovery Number: 30
Failed Recovery Death Probability: 9. Roll for Death Probability after Phase III, not Phase II.
Postrecovery Debility: Fatigue at level 2 for 20 weeks

The infection number means there's about an 85% chance of catching it if exposed (5 or higher on 2d6), while the recovery number is higher than any disease in the book (rabies is at 26). The death probability means 90% will die after Phase III, and any survivors (either due to treatment or random chance) will be moderately fatigued for almost 5 months. Some treatment is possible, but it has to be quick, and it's unlikely to be effective (the roll is a d10 + treatment modifiers + doctor's Medical Diagnosis skill + infected person's Constitution). The disease can be tweaked to last longer or shorter in Phase III, have different Postrecovery Debilities, have a higher or lower Infection Number, etc. I would rule a bite should count as exposure to infected fluids.

[Enfield]

I like it. Just for the heck of it, I rewrote it like a disease from the v2.2 rule book with some fill-in-the-blanks guesses for things that weren't mentioned in the original write-up:

S1R1
Transmission: Contact with infected fluids (saliva), able to survive on surfaces for ~24 hours. Infection Number 5.
Symptoms:
Phase I: Fatigue, dizziness, fever, sneezing
Phase II: Delirium, amnesia, muscle spasms, dementia
Phase III: Hallucination, violent psychosis
Diagnosis: Formidable
Misdiagnosed As: Influenza or minor disease
Treatment: Relief of symptoms (+2), Antibiotic- (+3) or Antibiotic+/- (+1). Treatment effective only in Phase I (or during Incubation). If multiple antibiotic types used, count only the best one.
Course of the Disease:
Incubation: 1 day
Phase I: 1d3 days
Phase II: 7 days minus Phase I
Phase III: 90 days
Base Recovery Number: 30
Failed Recovery Death Probability: 9. Roll for Death Probability after Phase III, not Phase II.
Postrecovery Debility: Fatigue at level 2 for 20 weeks

The infection number means there's about an 85% chance of catching it if exposed (5 or higher on 2d6), while the recovery number is higher than any disease in the book (rabies is at 26). The death probability means 90% will die after Phase III, and any survivors (either due to treatment or random chance) will be moderately fatigued for almost 5 months. Some treatment is possible, but it has to be quick, and it's unlikely to be effective (the roll is a d10 + treatment modifiers + doctor's Medical Diagnosis skill + infected person's Constitution). The disease can be tweaked to last longer or shorter in Phase III, have different Postrecovery Debilities, have a higher or lower Infection Number, etc. I would rule a bite should count as exposure to infected fluids.

very nice work, thank you. I agree with the bite, I also think (since I'm using a bit of the Crossed as inspiration) that other fluid exchange (french kissing, sexual intercourse, swallowing bodily fluids) should also count, as would getting fluids into an open wound. However I felt that the Crossed and 28 Days Later viruses worked TOO quickly; for a virus that's actually too fast and would cause crash and burn far too quickly. For example, let's say that four people get the virus and rapidly change to the last stage, then if they're suddenly shot they're dead, that's it. If they manage to get home and then infect others, that's a virus that's transferring at the top of its game.


I like the 90 day limit I think that's very reasonable, and I think I am going to make it a calculation of weeks to months, so for instance post stage iII 1d6 x 10 days on average, since different individuals will have different physical degrees of strength and con, and also be subjected to different combined bodily stresses depending on environment, etc.

[cawest]

john ringo has a zombie book line (black tide rising) that use biologic zombies. it is a good set of reads. very gun and small group fighting heavy.

[Enfield]

john ringo has a zombie book line (black tide rising) that use biologic zombies. it is a good set of reads. very gun and small group fighting heavy.

Cool. I will check that out as well, thank you.

[pmulcahy11b]

I like it. Just for the heck of it, I rewrote it like a disease from the v2.2 rule book with some fill-in-the-blanks guesses for things that weren't mentioned in the original write-up:

S1R1
Transmission: Contact with infected fluids (saliva), able to survive on surfaces for ~24 hours. Infection Number 5.
Symptoms:
Phase I: Fatigue, dizziness, fever, sneezing
Phase II: Delirium, amnesia, muscle spasms, dementia
Phase III: Hallucination, violent psychosis
Diagnosis: Formidable
Misdiagnosed As: Influenza or minor disease
Treatment: Relief of symptoms (+2), Antibiotic- (+3) or Antibiotic+/- (+1). Treatment effective only in Phase I (or during Incubation). If multiple antibiotic types used, count only the best one.
Course of the Disease:
Incubation: 1 day
Phase I: 1d3 days
Phase II: 7 days minus Phase I
Phase III: 90 days
Base Recovery Number: 30
Failed Recovery Death Probability: 9. Roll for Death Probability after Phase III, not Phase II.
Postrecovery Debility: Fatigue at level 2 for 20 weeks

The infection number means there's about an 85% chance of catching it if exposed (5 or higher on 2d6), while the recovery number is higher than any disease in the book (rabies is at 26). The death probability means 90% will die after Phase III, and any survivors (either due to treatment or random chance) will be moderately fatigued for almost 5 months. Some treatment is possible, but it has to be quick, and it's unlikely to be effective (the roll is a d10 + treatment modifiers + doctor's Medical Diagnosis skill + infected person's Constitution). The disease can be tweaked to last longer or shorter in Phase III, have different Postrecovery Debilities, have a higher or lower Infection Number, etc. I would rule a bite should count as exposure to infected fluids.

That's something Zombie movies leave them out that makes them more tense and more final for the victims, but also more fake -- the possibility of recovery from the illness. But I would also think that the cleanup of necrotic tissue on a recovering victim would be daunting, but necessary (and one of those diseases where part of the cure is worse than the disease, or possibly even fatal).

[swaghauler]

I like it. Just for the heck of it, I rewrote it like a disease from the v2.2 rule book with some fill-in-the-blanks guesses for things that weren't mentioned in the original write-up:

S1R1
Transmission: Contact with infected fluids (saliva), able to survive on surfaces for ~24 hours. Infection Number 5.
Symptoms:
Phase I: Fatigue, dizziness, fever, sneezing
Phase II: Delirium, amnesia, muscle spasms, dementia
Phase III: Hallucination, violent psychosis
Diagnosis: Formidable
Misdiagnosed As: Influenza or minor disease
Treatment: Relief of symptoms (+2), Antibiotic- (+3) or Antibiotic+/- (+1). Treatment effective only in Phase I (or during Incubation). If multiple antibiotic types used, count only the best one.
Course of the Disease:
Incubation: 1 day
Phase I: 1d3 days
Phase II: 7 days minus Phase I
Phase III: 90 days
Base Recovery Number: 30
Failed Recovery Death Probability: 9. Roll for Death Probability after Phase III, not Phase II.
Postrecovery Debility: Fatigue at level 2 for 20 weeks

The infection number means there's about an 85% chance of catching it if exposed (5 or higher on 2d6), while the recovery number is higher than any disease in the book (rabies is at 26). The death probability means 90% will die after Phase III, and any survivors (either due to treatment or random chance) will be moderately fatigued for almost 5 months. Some treatment is possible, but it has to be quick, and it's unlikely to be effective (the roll is a d10 + treatment modifiers + doctor's Medical Diagnosis skill + infected person's Constitution). The disease can be tweaked to last longer or shorter in Phase III, have different Postrecovery Debilities, have a higher or lower Infection Number, etc. I would rule a bite should count as exposure to infected fluids.

Nice write-up. The only issue I have with it is GDW's unrealistic/inaccurate depiction of disease treatment. This is the same issue GDW had with fuel (considering Methanol a viable liquid fuel and using AvGas for jets). GDW fails to fully and distinctly describe the diseases in their books and it will often result in an incorrect prescribed treatment. That major failure being the LACK OF DISTINCTION between a BACTERIAL DISEASE and a VIRAL DISEASE. Why is this distinction so important Because NO antibiotic made will work on a Virus. Viruses are also MUCH SMALLER than Bacteria and can be missed by water and air filters because of it. A Virus also needs a living host to inhabit. It can only live for a day or two OUTSIDE of a living cell before dying itself (some can survive longer in a liquid environment).
Because of the Virus's immunity to bacteria and the fact that it frequently "mutates" from host to host, it can be VERY DIFFICULT to cure. It takes a Vaccine made from either a dead or a greatly weakened virus combined with other compounds to enable the body to generate the appropriate defense against the disease. The other option is a Viral Suppression Therapy. Some examples of Viral Suppression Therapy would include the invasive program of pills and intravenous treatment for HIV, Flu and Shingles Shots to prevent getting or at least reducing the severity of a viral strain if you contract it. Another example of a Viral Suppression Therapy would be the prescribing of Tamiflu for a severe flu outbreak. Some Suppression Therapies (like Tamiflu) would grant a +1 to treatment while others (like aggressive HIV treatment) would grant a +2. A VACCINE would provide a cure.

The only other issue I see would be the 90-day "runtime." I'm assuming a 28 Days Later kind of infection here where the "infected" are actually ALIVE but mad and therefore, NOT DEAD MEN WALKING. Most hemorrhagic fevers raise the core body temperature WELL over 100F. This results in a very high thirst and general dehydration. One of the issues with dehydration is that it causes your blood to "thicken," so that it carries less O2 and nutrients. Therefore, even if an "Infected" is eating & drinking regularly (and the virus is consuming less than half the created cellular energy to replicate itself), they will STILL starve to death faster than an uninfected subject. Additionally, high body temps and a constant adrenaline surge will burn out a body pretty fast. Anyone who has ever been in a fight KNOWS that it feels like you ran a marathon just a few minutes afterward. This is the "letdown" from an adrenaline surge. A CONSTANT adrenaline surge would eventually "burn you out," especially if you're fighting off a major viral infection. I think an infected trapped where they cannot feed will die in 30 days and most infected will succumb to death from malnourishment (even despite eating constantly) in about 60 days.

[swaghauler]

On Infected Subjects

One of the big issues I have with "Zombie Infestations" is the apparently DEADLY nature of zombies in HTH. They can bite a 6" deep wound in a guy's shoulder and rip out a person's "guts" with their bare hands. I'm sorry, but people are much harder to disembowel than most zombie movies make them. Skin is tough enough that ballistic gel (calibrated to replicate human muscle) is said to represent 1/3rd of its penetration when considering skin (ie 3" of penetration in ballistic gel is equal to the penetration of just a man's SKIN).
To replicate this, I'd give a zombie a killing bite of from 0 (no penetration) to 2 points of wound damage (roll 1D3-1). Most HTH attacks would be "grappling attacks" designed to immobilize their "prey" so that they can "eat" (bite) that prey. This will result in a number of people getting bitten but then escaping from the grasp of their attackers.

Zombie/Infected Intelligence:

I can see "classes" of Infected with varying "cognitive function" based on their rate of disease progression. The newly infected may be functioning like a normal human "on a bad acid trip." They will be "attacking" because of the hallucinations they are experiencing and they may be very high functioning. Those at the end of the disease's "progression" may be barely functional, unable to climb stairs, blocked by closed doors and falling off of roofs or cliffs as though they were unable to perceive those obstacles. Here is an idea I have to mirror this cognitive decline:

Shufflers:

These Infected are at the END of the disease progression. They can only perceive normal objects up to INT X 5 meters away (explosions or gunfire will be perceived MUCH further away). They cannot open closed doors unless they push open (like fire doors), climb stairs WITHOUT a roll (INT+AGL or less on 1D20) and cannot "understand" glass (they will "claw" at it unable to understand why they cannot move towards the "food" they are seeing). Shufflers will be primarily nocturnal as bright light will hurt their eyes (like migraine sufferers) due to swelling of their brains. They will also move like drunks and have a reduced movement.

Shamblers:

These Infected are more "high functioning" than the aforementioned "Shufflers." They can climb stairs without a task roll. They are STILL blocked by glass (due to the same perception issues as "shufflers") but can climb ladders, fences, and open doors with latches (handles and knobs) if they roll against (INT+AGL). They can perceive objects at INT X 10 meters and HEAR loud noises MUCH further. "Shamblers" may or may not be nocturnal and several of them may group together just following each other in search of food. Some "Shamblers" may conduct fairly complex activities in a repetitive manner, playing an instrument for instance or loading items into bins or shelves. This is attributed to "learned instinct" or "muscle memory"

Runners:

The highest functioning and most dangerous Infected. Most of these will be Phase II infected but there are Phase III "Runners." They can open doors, climb fences, and ladders. They may even use melee weapons if they roll INT or less on 1D10. They can perceive window glass and will try to break it. They are as fast as any other human. They will also "scream" or "roar" when they see "food" which can attract other Infected.

An Infected is "classified" by the chart below:

Phase II
Infected is a Shuffler if they roll 5 or more over INT on 1D10.
Infected is a Shambler if they roll over INT on 1D10.
Infected is a Screamer if they roll INT or Less on 1D10.

Phase III
Infected is a Shuffler if they roll OVER INT on 1D10.
Infected is a Shambler if they roll INT to 4 UNDER INT on 1D10.
Infected is a Screamer if they roll 5 UNDER INT on 1D10.

Each week the Infected is in Phase III REQUIRES a new classification check with a reduction of 1 to INT. This represents the debilitation of long-term infection.

[Enfield]

That's something Zombie movies leave them out that makes them more tense and more final for the victims, but also more fake -- the possibility of recovery from the illness. But I would also think that the cleanup of necrotic tissue on a recovering victim would be daunting, but necessary (and one of those diseases where part of the cure is worse than the disease, or possibly even fatal).

I actually think that having recovery possibilities does make it more intresting. Because in most zombie or infected movies you do know after a bit how long infection spreads. In the original George A. Romero series it might take hours or days for a person to eventually die and become a zombie, whereas dying quicklyl from blood loss or shock would result in immediate turning. The Walking dead works on a similar logic. Whereas in 28 Days Later and similar franchises (or The Crossed series) infection spreads within minutes if not seconds in some cases. It is inevitable.

However this means that you automatically know what to do and have no moral dilemmas. I think it's more interesting to have those. It also requires effort--you might have to keep someone on observation, run successive tests, etc.

[Enfield]

One of the big issues I have with "Zombie Infestations" is the apparently DEADLY nature of zombies in HTH. They can bite a 6" deep wound in a guy's shoulder and rip out a person's "guts" with their bare hands. I'm sorry, but people are much harder to disembowel than most zombie movies make them. Skin is tough enough that ballistic gel (calibrated to replicate human muscle) is said to represent 1/3rd of its penetration when considering skin (ie 3" of penetration in ballistic gel is equal to the penetration of just a man's SKIN).
To replicate this, I'd give a zombie a killing bite of from 0 (no penetration) to 2 points of wound damage (roll 1D3-1). Most HTH attacks would be "grappling attacks" designed to immobilize their "prey" so that they can "eat" (bite) that prey. This will result in a number of people getting bitten but then escaping from the grasp of their attackers.

Zombie/Infected Intelligence:

I can see "classes" of Infected with varying "cognitive function" based on their rate of disease progression. The newly infected may be functioning like a normal human "on a bad acid trip." They will be "attacking" because of the hallucinations they are experiencing and they may be very high functioning. Those at the end of the disease's "progression" may be barely functional, unable to climb stairs, blocked by closed doors and falling off of roofs or cliffs as though they were unable to perceive those obstacles. Here is an idea I have to mirror this cognitive decline:

Shufflers:

These Infected are at the END of the disease progression. They can only perceive normal objects up to INT X 5 meters away (explosions or gunfire will be perceived MUCH further away). They cannot open closed doors unless they push open (like fire doors), climb stairs WITHOUT a roll (INT+AGL or less on 1D20) and cannot "understand" glass (they will "claw" at it unable to understand why they cannot move towards the "food" they are seeing). Shufflers will be primarily nocturnal as bright light will hurt their eyes (like migraine sufferers) due to swelling of their brains. They will also move like drunks and have a reduced movement.

Shamblers:

These Infected are more "high functioning" than the aforementioned "Shufflers." They can climb stairs without a task roll. They are STILL blocked by glass (due to the same perception issues as "shufflers") but can climb ladders, fences, and open doors with latches (handles and knobs) if they roll against (INT+AGL). They can perceive objects at INT X 10 meters and HEAR loud noises MUCH further. "Shamblers" may or may not be nocturnal and several of them may group together just following each other in search of food. Some "Shamblers" may conduct fairly complex activities in a repetitive manner, playing an instrument for instance or loading items into bins or shelves. This is attributed to "learned instinct" or "muscle memory"

Runners:

The highest functioning and most dangerous Infected. Most of these will be Phase II infected but there are Phase III "Runners." They can open doors, climb fences, and ladders. They may even use melee weapons if they roll INT or less on 1D10. They can perceive window glass and will try to break it. They are as fast as any other human. They will also "scream" or "roar" when they see "food" which can attract other Infected.

An Infected is "classified" by the chart below:

Phase II
Infected is a Shuffler if they roll 5 or more over INT on 1D10.
Infected is a Shambler if they roll over INT on 1D10.
Infected is a Screamer if they roll INT or Less on 1D10.

Phase III
Infected is a Shuffler if they roll OVER INT on 1D10.
Infected is a Shambler if they roll INT to 4 UNDER INT on 1D10.
Infected is a Screamer if they roll 5 UNDER INT on 1D10.

Each week the Infected is in Phase III REQUIRES a new classification check with a reduction of 1 to INT. This represents the debilitation of long-term infection.

I agree about the bite. I think that one exception I might have about this is that there are some extremities that might be more vulnerable to biting than others, but generally I agree. I was scoffing at one of the scenes in "The Walking Dead" and a friend of mine said "This is dumb. Imagine getting five or six of your friends really drunk or high and then trying to catch and eat a live horse." Zombie/infected attack abilities are over the top.

However the key to my take on the disease is that it is a disease that is the primary problem, not that they just rip you to pieces. So I generally like your take on it. I also like the classifications. The shambler idea is what I have been using for people who are infected but are more confused and delirious than really dangerous, though they can be dangerous in some cases. Unfortunately this is part of why the infection ends up spreading, is that the early stages don't seem dangerous and so many of these people were not restrained.

I have furthermore made it clear that except for the very thinnest cloth that wearing clothing, or covering of any kind, holds off human nails and teeth. The main danger would be getting a bunch of them on you and having the clothing or other protection dislodged.

[The Dark]

I actually think that having recovery possibilities does make it more intresting. Because in most zombie or infected movies you do know after a bit how long infection spreads. In the original George A. Romero series it might take hours or days for a person to eventually die and become a zombie, whereas dying quicklyl from blood loss or shock would result in immediate turning. The Walking dead works on a similar logic. Whereas in 28 Days Later and similar franchises (or The Crossed series) infection spreads within minutes if not seconds in some cases. It is inevitable.

However this means that you automatically know what to do and have no moral dilemmas. I think it's more interesting to have those. It also requires effort--you might have to keep someone on observation, run successive tests, etc.

Yes, this was the gist of what I was thinking (but couldn't put into words) when I kept in the potential for recovery. It creates a much more interesting (to me, at least) moral dilemma to know that while the zombie will probably die anyway, there's a possibility of recovery. Another area to think about is how they react to less-than-lethal defenses - how much does CS discourage a zombie horde What about beanbag rounds or tasers (For a potentially more light-hearted take, can you distract them with hamburgers)

The only issue I have with it is GDW's unrealistic/inaccurate depiction of disease treatment. This is the same issue GDW had with fuel (considering Methanol a viable liquid fuel and using AvGas for jets). GDW fails to fully and distinctly describe the diseases in their books and it will often result in an incorrect prescribed treatment. That major failure being the LACK OF DISTINCTION between a BACTERIAL DISEASE and a VIRAL DISEASE. Why is this distinction so important Because NO antibiotic made will work on a Virus. Viruses are also MUCH SMALLER than Bacteria and can be missed by water and air filters because of it. A Virus also needs a living host to inhabit. It can only live for a day or two OUTSIDE of a living cell before dying itself (some can survive longer in a liquid environment).
Because of the Virus's immunity to bacteria and the fact that it frequently "mutates" from host to host, it can be VERY DIFFICULT to cure. It takes a Vaccine made from either a dead or a greatly weakened virus combined with other compounds to enable the body to generate the appropriate defense against the disease. The other option is a Viral Suppression Therapy. Some examples of Viral Suppression Therapy would include the invasive program of pills and intravenous treatment for HIV, Flu and Shingles Shots to prevent getting or at least reducing the severity of a viral strain if you contract it. Another example of a Viral Suppression Therapy would be the prescribing of Tamiflu for a severe flu outbreak. Some Suppression Therapies (like Tamiflu) would grant a +1 to treatment while others (like aggressive HIV treatment) would grant a +2. A VACCINE would provide a cure.

True. My main goal was to make it so there was a possibility of Phase I recovery IF you were already robust AND had a good doctor AND rare (in a post-apoc scenario) medicines. Someone who wanted an in-universe rationalization that probably makes no sense but sounds cool is that the virus doesn't directly infect humans, but rather infects a bacterium that then infects humans. Without the bacterium's protective coating, the virus dies in the human body, so the anti-bacterial is an indirect attack on the virus (I'm pretty sure that's total BS and would be shocked if a virus actually worked that way, but it'd be good enough for Hollywood ).

To replicate this, I'd give a zombie a killing bite of from 0 (no penetration) to 2 points of wound damage (roll 1D3-1). Most HTH attacks would be "grappling attacks" designed to immobilize their "prey" so that they can "eat" (bite) that prey. This will result in a number of people getting bitten but then escaping from the grasp of their attackers.

Which, in turn, would make the unarmed combat supplement more useful, since different martial arts give bonuses or maluses to the "escape" action to get out of grapples.

[swaghauler]

True. My main goal was to make it so there was a possibility of Phase I recovery IF you were already robust AND had a good doctor AND rare (in a post-apoc scenario) medicines. Someone who wanted an in-universe rationalization that probably makes no sense but sounds cool is that the virus doesn't directly infect humans, but rather infects a bacterium that then infects humans. Without the bacterium's protective coating, the virus dies in the human body, so the anti-bacterial is an indirect attack on the virus (I'm pretty sure that's total BS and would be shocked if a virus actually worked that way, but it'd be good enough for Hollywood ).

I'm not going to say a Bacterial/Virus hybrid couldn't happen in the age of Biology and Eugenics. I'm not sure what kind of gene-splicing it might take though.