the only possible way to workaround this issue at the moment, is attempt to kite the dragon away. i have 2 occurance as such, 1 as the southern mining town south of Windhelm, and the other is at the Orc camp south east. both times dragon attack, killed few NPC. I keep on reload and fight the dragon, when the dragon died, i chk, still end up with NPC killed. then i tried another approach (starting at the mining town) the dragon attack soon after i leave the inn, so i load the game prior to that save, once outside, i keep run to a place furthest away from these population, the dragon does seem to follow you in a way. the catch is sometime when you fighting the dragon, it may fly off and go attack the town. so keep save the gam during the fight, as long as the dragon is not bothering the town/npcs. i managed to use such "crude" kiting to avoid the npc getting killed.
I tried that a few times but the dragon rarely follows me anywhere. In fact it barely ever pays any attention to me, and I'm Dragonborn. Instead, it wants to eat all the idiots that are pulling it's tail and socking it in the legs with their fists, stabbing it's toes and so on... lol
But yeah I had a situation where I saved the game just outside of Riverwood (I didn't fast travel), and after the game saved a dragon appeared a minute later and headed for the town. I followed it and after it died I noticed Gerdur had died. Well I reloaded the save to see if I could avoid her dying and I did but then the game locked up my PS3 so I had to try again. The 3rd time I thought I did it but found Gerdur's body again. So I had to do it a 4th time and finally got away with it without the game freezing and making me hard boot out of my system. Then I saved the game over an old save and made a new character, only to find out the new character save slot saved over my save after that dragon fight (The famous manual save overwrite bug that isn't being addressed in the next patch). So I had to load the save before the dragon attacked again and this time Alvor died. So I reloaded again and finally did it without anyone dying and saved it on 3 new slots to make sure the game doesn't eat the save if I start a new game. I have unfortunately lost a few builds with that save slot overwrite bug and it wasn't until the dragon instance that I finally knew it couldn't be me so I checked online and sure enough I found out it was another bug and how to avoid it in the future.
This whole process took 2 hours, and doesn't really help my case in this thread. Just thought I'd share that experience. The reason why it doesn't help my case is I think Gerdur and Alvor SHOULD fight any dragon, just wish the dragon would come after me and not them all the time. I will always reload a save before a dragon attacks so a person I don't want to die doesn't die. But if a guard, a follower, a companion, or an elderly person, or a boring NPC I don't care about such as the town drunk or a bard dies from a dragon I won't care at all. I think some people SHOULD die from dragons even some minor quest givers. But I will avoid it if possible or if it's someone I like. I still think the A.I. could be better though so when NPC's who "should" be fighting the dragon's life gets low they try to get farther away and maybe heal themselves. They could still die, just not quite so easily.
Before the game came out (like 6 months before) I was on the Bethblog and I recommended that dragon's attack towns, just not very often but nope, they attack way too often in my opinion. I also recommended that when a dragon attacked, NPCs run away except for guards, followers, warriors, and specific passer-bys which I recommended they create JUST FOR DRAGON ATTACKS. I'm talking about like traveling NPCs on horses and with carriages and religious monks and such, that when a dragon attacks, these "dragon food people" with no associated quests and little dialog, would spawn just outside of the town and would be the one's the dragons mostly go for. That way a lot of quest givers don't die, but you would still see cool things like dragons swooping down on horses and monks, and torching wooden carriages and see bodies flying around. It's obvious they didn't listen to my recommendations. lol... I will just say once again I don't think the way dragon attacks are now are horrible or game-breaking, but the A.I. of the NPCs and the dragons themselves, could have been a lot better and a lot more realistic, and it wouldn't have been that hard to implement.