Fallout 4

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A communist bioweapon that has lain dormant since 2077 has somehow been activated in the Commonwealth. Experience the leadership pressures of pandemic management by balancing economic productivity, travel limitations, a whining population and investments in PPE.

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A communist bioweapon that has lain dormant since 2077 has somehow been activated in the Commonwealth. Experience the leadership pressures of pandemic management by balancing economic productivity, travel limitations, a whining population and investments in PPE. 

[ Change must come though the barrel of COVID ] 

Install this non intrusive solution at any time in any game, it makes no static changes to your game at all. Nothing happens until there is sufficient workshop population in the Commonwealth for the COVID77 virus to be acvtivated and spread. Maybe from eating too many uncooked pangolin iguana bits ?
For an instant challenge install into an existing game with a network of well recruited workshops. If you start a new game it will take a while to reach the default starting conditions of 10 workshops with 5 or more non robot population. If you can't handle the anticipation, craft a [ COVID77 Configuration ] item at Chemlab to change conditions or force COVID to trigger with just one workshop. You can grab Sanctuary straight out of Vault 111 and get infected, although the pandemic will probably only run for 24 hours.

If you enjoy unfolding surprises and challenges don't read the spoiler section. The experience is fully signposted in game and has been tested doable by average Americans without any more info. Read the spoiler section if your are not average, American, need to understand the detail or are deperate to post a list of "does it do X, Y and Z" questions that are all probably covered.

Read this if you really need to know how it works.


Spreading and managing infections

COVID77 only affects humans. The player needs to manage themselves, companions, followers, owned workshop assigned actors and one other group.  Other humans at unowned workshops, Diamond City, Goodneighbor and of course hostiles will sort themselves out as there are technical limitations on the player interacting to manage them without conflicting with all your other mods that inject dialog or add activate menus.

Once population trigger conditons are met this starts with some index infection vectors that you will discover. New human workshop recruits (coming from you dont know where) and human provisioners (doing provisoner things on the road) have a high chance of introducing new infections.

Infection spreads between settlement populations by infected humans travelling, robots are not a vector. If your workshops are not actively recruiting new actors, are mostly robots and there is no human traffic when this starts then COVD77 will not spread far.

You will not know the actual condition of infections and incapacitations at a workshop until it is visited (due to "non persistent objects"). There is an objective to check them all out and you will discover a tool to detect infected actors.

Buying and fitting face coverings is a must (Surgical mask, Bandanna, Gasmask, Hoods, Full face helmets, PA helmets, Hazmats) to slow the spread. As time passes most vendors will start to stock face coverings, including your workshop vendors. Focus on doctors and workshop clinics. You may come across new vendors looking to cash in on the PPE opportunity like those government contracts with family members.
Each infected human has a base chance of transmitting the virus to other unvaccinated humans based on face/mouth covering.  The transmission at a location will increase proportional to the number of infected humans, resident or visiting. The base infection rate is 10% and wearing a mask reduces transmssion by 70% at each end, so defaults deliver actor:actor rates of:

Uncovered to Uncovered chance 10% (10 or more uncovered infections will 100% infect everyone else uncovered).
Uncovered to Covered chance 3% 
Covered to Covered chance 0.9%

For high risk travelling actors the rates are:
Uncovered to Uncovered chance 30%
Uncovered to Covered chance 9% 
Covered to Covered chance 3%

What happens to infected humans ? Nothing. Nothing at all, they just silently infect other uninfected humans unless ...


An infected human that is assigned to a workshop (not a currernt player follower, dismissed companion or quest bound) has a chance of becoming incapacitated. This includes normal human provisioners who are spreading the infection, so keep an eye on your supply lines.
An incapacitated actor will be unasisgned from any work and sent to a free bed at their home workshop. If there are no free beds they will collapse in place in the workshop area. Incapacitated actors will stay in bed until vaccinated/cured, but the player can still speak with them to trade, equip masks and vaccinate. This is non leathal and does no actual damage to the actors. 

Of course if the player is noticed killing friendly infected or incapacitated workshop actors that will trigger the usual aggro and happiness debuffs. That is one of many possible pandemic management strategies.


This solution is non lethal and does not kill any of your existing actors. Any actors that may be required to die are all new spawns which will not affect workshop happiness or companion affinity.

Vaccination & cure (same thing)

Once vaccines are unlocked, infected and incapacitated human actors can be vaccinated and cured by the player if there is vaccine in the inventory;

(a) Using a [ Vaccinate ] actor activation menu perk.

(b) One time "Take the cure" dialog with infected actors. This should take precidence over any other dialog, but it may take a couple of "talks" to assert in the dialog stack.

(c) Placing a vaccine in infected actor inventory either through standard trade dialog or any solution that can open the actor trade menu will self administer (Combat Settlers, Combat Followers, FCOM & etc). Even console [ refid.OpenActorContainer 1 ] will work.

(d) Reverse pickpocket placing a vaccine in infected acotor inventory will self administer (still triggers hostility if detected).

Once a human has been vaccinated they will no longer carry or transmit the virus so do not need a face cover. Vaccination state is not reported to comply with PII and privacy legislation so probably best to equip everyone if doing it manually.

Management Reporting

The player will find a regenerating [ COVID77 Report ] aid item for stats reporting and configuration menu. If lost, replacements can be crafted at Chemlab.

Infected workshops are automatically marked with a [ COVID Infeted ] biohazrad sign which can be activated to provide the same  COVID77 report. When the workshop is cleared of infections it turns into a [ COVID Clear ] sign. When the quest ends they are all removed.

The report shows global and local workshop protection and infection stats (see pics) with menu options to:

[ Equip Facemasks ] If the player is at a workshop with surgical masks in inventory, automatically equip them in priority order on uncovered: provisioners, medics, incapacitated, infected, uninfected. Note that this can trigger the actor reset to their default outfit. Any other masks need to be manually traded and equipped.

[ Vaccinate Workshop ] If the player is at an infected workshop with vaccine in inventory, automatically vaccinate humans in priority order: incapacitated, infected uncovered, infected covered. Uninfected humans are not automatically vaccinated to protect the supply.

[ Vaccination Perk ]  Use this to add/remove the actor vaccination activation menu perk if it conflicts with other mods which use the addactivate perk to add activate menus to actors.  Infected/Incapaciated actors can still be vaccinated through speech.


The Chemlab craftable [ COVID77 Configuration ] AID item menu allows configuration of:

Starting Triggers:
Number of owned workshops (default 10).
Minimum workshop population to count, excluding robots  (default 5).

Infection Rates:
The minimum game hours between actor infection tests (default 24). 
Infection transmission rate uncovered (default 10%).
Infection transmission covered multiplier (default x 0.3).
High risk tranmission multiplier for player, followers, caravans and provisioners (default x 3.0).
Incapacitation rate for infected actors (default 20%).

Vaccine effectiveness (default 95%).
Clear Vaccine lockout timer (for scenario reset).

Map mark active InfectionBots (switch).

Force > TRIGGER COVID <  now with one or more owned workshop no population needed.

Force > SHUTDOWN COVID < clears all symptoms and shuts down the quest which is not restartable in that save.

Known Issues & considerations

(1) If you run a timescale slower than the default 20:1 and/or start with a small population, the new infection rate will be slow. At 1:1 you may be able to run round and mask up all workshops and develop the cure before infection updates can create a pandemic. Even after several hundred test runs it has not been possible to establish a perfect model for (timescale x starting population x infection rates) to deliver a fantastic experience under all conditions. You can tune the infection rates with the configuration menu or console to account for your specific conditions.

(2) When approaching a workshop the scripts have to collect all actor states, build the infection vector model and then update actors. To ensure all workshop resources are loaded, this starts after base game reset workshop has completed and the player is less than 5,000 game units from the workshop and then takes around 5 seconds to update 10 actors.  You may see live actors in the workshop area disappear when they are picked for incapacitation and sent to bed without dinner. Its a balance of visual user experience over accuracy of numbers.

(3) The automatic equip facemasks workshop function can sometimes cause actors to reset to their default outfit. Its a bug in the scripted EquipItem() base game function and there is no workaround except to not use the function. Infected actors with a base game surgical mask in inventory will automatically equip them OnLoad if they are suffering this reset.

(4) The workshop actor incapacitation-unassign-and-send-to-bed function may upset solutions that depend on specific actors assigned to specific jobs, or that use workshop assigned actors for quests without releasing from the workshop. 

SimSettlements2 actors Aiden, Jake, Paul who do this are automatically excluded. Before COVID activates you can add SKK_COVIDNeverInfectKeyword to actors:

(4.1) For new games add the keyword to __NPC ActorBase forms using CK or xEdit

(4.2) Use xEdit to add the in game ObjectReferences to FormList SKK_COVIDNeverInfectList to automatically add the keyword on game load.

(4.3) Use the PC console to pick an actor and [ AddKeyword SKK_COVIDNeverInfectKeyword 

(5) The infected actor vaccination perk will conflict with other solutions that add activate menu choices to human actors (quick trade, follower menu, settler menus & such) so no menu options end up showing. If disabled in the [ COVID77 Report ] menu, there is backup vaccination dialog or use actor trade which can trigger vaccination.
(6) If you have other solutions that depend on specific equipped headgear which do not use the covered mouth detection keywords:  AnimHelmetCoversMouth, ClothingDogmeat, dn_PowerArmor_Helmet you will have problems limiting the spread.

Compatibility Considerations

The mod has no dependencies on extenders or DLCs and does not change any existing base game scripts, assets or objects. It is 100% pure new Creation Kit forms and scripts which means that it has no load order dependencies.

(1) If running with Fallout 4-76, update that to version 037 (or later) and disable replacement of dead humans so quest targets are not removed. 

As this mod was published after November 2019 it depends on Fallout4.exe (or later).

Nexus PC manual installation & disable

Copy SKKCovid77.esp and  SKKCovid77 - Main.BA2 and SKKCovid77 - Textures.BA2 to your...\Fallout 4\Data directory and add to Plugins.txt, or enable in the Bethesda mod menu, use a mod manger or however you organise. 

As this adds new actor attributes and meshed objects to the game which can be in the world or inventories, once the quest starts do not remove this from a savegame unless you are totally mad and accept all consequences up to and including bodily injury or death.

Nexus FAQ

(1) Why is the infection limited to human settlers and followers ? Because this is art imitating life and there is no robust method to vaccinate any arbitrary actor in the game without generating a tonne of potential dialog/activate menu conflicts.

(2) Why do infections only happen when the player is around ? Most actors are "non persistent" so cant be found to query for stats like "are you human race ?" unless they are 3d loaded which means in the active uGrids around the player. Its how the game platform is designed and part of the reason why workshop stats are always wrong.

(3) Why is there no ESL version ? Because life already contains sufficient hassle maintaining 50 scripted ESP solutions. 

(4) Is this controversial or insensitive ? The whole Fallout franchise is based on the premise that China nuked America in a fictional 2077 reality. This is a simulation of China also planning to infect America with a Bioweapon in that fictional conflict. But ignorance can always find something to be angry or outraged about so just start shouting.

(5) How long did this take to produce ? Around 160 hours total effort, of which a third was core development and code testing. Two thirds were UX flow and infection rate testing. That's ~ 60 hours of pure testing to generate over 500 data sets for the infection models, but it's really just an amateur-hour game mod !

Console Configuration default settings

To adjust the infection and incpacitation rates without popping the config menu:


set SKK_COVIDGameHoursToUpdate to 24;
Range 0 to 65535. The minimum number of game hours between player visists and report runs to check infections. Should be the same as the WorkshopDailyUpdate recruitment cycle. You can not cheese the system by staying away as the infection calculations include days since last visit. To accelerate infections set to a low number, or even Zero. 

set SKK_COVIDTxUncoveredBase to 10;
Range 0 to 100. The base %chance of infected:uninfected transmission if both actors are uncovered every SKK_COVIDGameHoursToUpdate period.

set SKK_COVIDTxCoveredMultipler to 0.3;
Range 0 to 1. The uncovered base value multiplier to get the covered value, is calculated for both transmitter and receiver. Stacks with the high risk mult.

set SKK_COVIDTxHighRiskMultiplier to 3.0;
Range 0 to 65535. The uncovered base value multiplier for high risk actors (player, follower, caravan, provisioner) will become infected each GameHoursToUpdate period on the road or infect others. Stacks with the covered mult.

set SKK_COVIDIncpacitationRate to 20;
Range 0 to 100. The %chance an infected actor will be sent to bed each GameHoursToUpdate period.

Example A the chance for a covered settler transmitter to infact another covered settler receiver:
( SKK_COVIDTxUncoveredBase * SKK_COVIDTxCoveredMultipler * SKK_COVIDTxCoveredMultipler )

Example B The chance for an uncovered provisioner trnasmnitter to infect a covered settler receiver:
( SKK_COVIDTxUncoveredBase * SKK_COVIDTxHighRiskMultiplier * SKK_COVIDTxCoveredMultipler )

SKK mods for Fallout4 will no longer be maintained on nexusmods.com from July 2021
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