Seeing as I can't find a thread that really spells out the whole Vaccine mission effort, here is my attempt at a summary, along with some spoiler coords. I don't have down all the names of the different brokers, but they are all either in the Naval Base Triton, or at Jameson Reach. The ones at Triton you can get missions immediately. The ones at Jameson won't talk to you until you unlock them by doing prior missions. You will only be able to get input from one broker at a time at Jameson. (apologies for misspelling, trying to enter info quick before I go to work):
Do the Triton missions first, there is a hunting mission, mining mission and exploration mission for missing ship. There is also a mission from broker down on the docks, called Up the Road or such. Not sure if it is also a requirement, but takes about 30 seconds to do, so might as well do it now. After completing the "missing ship" mission, follow up is to get a water sample from the Oasis and return as quickly as possible. I have heard that for some people the water sample got "corrupted" and they had to repeat this one, sometimes a few times. Not sure if it is related to how fast you get back or not, but might factor in. Some TP'd back and had corrupted samples, another I know flew back in Slepnier and was okay.
After you complete all of those missions return to the hunter broker (the ninja suit one) he will now have a new mission that is to go to Jameson Reach and gives you a note to take.
Missing ship: ~399, 615
At Jameson, see the specified broker with the note and you get started on a series of missions. You have to move from broker to broker to get the next ones after completing each, I might have mixed up the order a bit, but will correct once I get home later. Most times there are no orange NPC dots at the locations you have to search out, so go by the coords and look around. Once you do a mission and return the same broker to complete, usually that broker is done and you have to go to each of the other brokers at Jameson to figure out who has been unlocked and now offers the next mission in the series. There are 3 brokers at the service center level, and one above on the cliff. The one above on the cliff is only for the very end.
Find missing tank: Tank coords - 36015, 60570, crawl around and click on tank until you get the mission completed message. Return to same broker.
Find black box/helicopter: Helicopter wreckage coords - 38660, 60360 - If you walk around the helicopter you will see the black box lying on the ground, click on it to get mission completed message. Return to same broker.
Kill the aetherex on the hilltop: coords provided in mission. Kill 20 Aetherex on each of two hilltops and return.
Find George: Coords - 36863, 59603 - Look around for a piece of wreckage, George is lying on the ground next to it. Click around until you get the mission step completed mission, return to same broker.
Collect perfect blood/goo/poison samples: - Pain in the butt, but you can hunt for Saba off island at any spawn on Calypso for example and still get credit. You don't see any samples in loot, it just increments the counter at random times for the sample/mob you are hunting. I had to kill about 20 Aetherex before my first sample, but then some came after only killing 1 or 2 more. I probably had to kill about 60-70 Aetherex, 30 Saba, and 50-60 Rextellum to get the 10 samples each. It's random though...and like I said, nothing shows in loot. In fact, I know for a fact I got a sample incremented on "no looters" when hunting Saba.
Collect 20 more poison samples: - First attempt fails, so you have to go back out and collect 20 poison samples from Rextellum. When you return with the samples, go to the broker up on the higher hill (Lys something?) Televator on the ground behind the service vehicle at Jameson to take you up to the level with a bunch of small structures, that broker and a bunch of soldiers. She will generate a new vaccine for you and administer it to you. It is permanent.
Drop down to the Major mission broker again and he will give you the Visit Middle Island mission. I haven't been able to figure out anything beyond that yet. Not sure anything is really working on the Middle Island. There are a couple structures in the NE (lighter area on the map). One is a teleporter up to the mothership that is firing on the volcano. Just walk into it. There are a number of soldier and other NPC both on the ground and up on the mothership, but none seem to be unlocked yet. At least you can get on the island and hunt/mine now though...have fun
Sorry for any inaccuracies & missing info, will try to be more complete later, but should answer most questions for the vaccine sequence. Overall I liked the extra dependencies they put into this series...little more hunting around to figure stuff out, although that extra 20 samples on Rex pissed me off
-Mack
P.S. Thanks to anyone who provided coords along the way
P.P.S. Komby, or anyone else...feel free to grab this info and put in opening post. I'm really busy with work this weekend, so won't have time to go in and fill in the blanks (broker names and coords, proper mission names, proper sequence at Jamieson, etc), so if someone else has the time/desire to do it, that'd be great