Attempting to guarantee immunity to viruses for virus_immune var.

code/datums/disease.dm

@@ -53,14 +53,15 @@ var/list/diseases = typesof(/datum/disease) - /datum/disease
 	// if hidden[2] is true, then virus is hidden from PANDEMIC machine
 
 /datum/disease/proc/stage_act()
+
+	// Some species are immune to viruses entirely.
+	if(affected_mob && istype(affected_mob, /mob/living/carbon/human))
+		var/mob/living/carbon/human/H = affected_mob
+		if(H.species.virus_immune)
+			cure()
+			return
 	age++
 	var/cure_present = has_cure()
-	//world << "[cure_present]"
-
-	if(carrier&&!cure_present)
-		//world << "[affected_mob] is carrier"
-		return
-
 	spread = (cure_present?"Remissive":initial_spread)
 	if(stage > max_stages)
 		stage = max_stages
@@ -126,7 +127,7 @@ var/list/diseases = typesof(/datum/disease) - /datum/disease
 			source = affected_mob
 		else //no source and no mob affected. Rogue disease. Break
 			return
-	
+
 	if(affected_mob.reagents != null)
 		if(affected_mob)
 			if(affected_mob.reagents.has_reagent("spaceacillin"))

code/modules/virus2/disease2.dm

@@ -66,6 +66,12 @@
 		if(prob(5))
 			mob.antibodies |= antigen // 20% immunity is a good chance IMO, because it allows finding an immune person easily
 
+	// Some species are flat out immune to organic viruses.
+	var/mob/living/carbon/human/H = mob
+	if(istype(H) && H.species.virus_immune)
+		cure(mob)
+		return
+
 	if(mob.radiation > 50)
 		if(prob(1))
 			majormutate()

code/modules/virus2/helpers.dm

@@ -3,25 +3,26 @@ proc/infection_check(var/mob/living/carbon/M, var/vector = "Airborne")
 	if (!istype(M))
 		return 0
 
+	var/mob/living/carbon/human/H = M
+	if(istype(H) && H.species.virus_immune)
+		return 0
+
 	var/protection = M.getarmor(null, "bio")	//gets the full body bio armour value, weighted by body part coverage.
 	var/score = round(0.06*protection) 			//scales 100% protection to 6.
 
 	switch(vector)
 		if("Airborne")
-			if(M.internal)
-				score = 6	//not breathing infected air helps greatly
-				var/obj/item/I = M.wear_mask
-
-				//masks provide a small bonus and can replace overall bio protection
-				if(I)
-					score = max(score, round(0.06*I.armor["bio"]))
-					if (istype(I, /obj/item/clothing/mask))
-						score += 1 //this should be added after
+			if(M.internal) //not breathing infected air helps greatly
+				return 0
+			var/obj/item/I = M.wear_mask
+			//masks provide a small bonus and can replace overall bio protection
+			if(I)
+				score = max(score, round(0.06*I.armor["bio"]))
+				if (istype(I, /obj/item/clothing/mask))
+					score += 1 //this should be added after
 
 		if("Contact")
-			if(istype(M, /mob/living/carbon/human))
-				var/mob/living/carbon/human/H = M
-
+			if(istype(H))
 				//gloves provide a larger bonus
 				if (istype(H.gloves, /obj/item/clothing/gloves))
 					score += 2