I know this is an "old" thread but, it pops back up every year so I thought I'd include my experience as I just recently did a flu clinic.
I think it's an odd process, there's very little communication and almost no human interaction with anyone in the company. You sign up online and do a test, then you're basically "hired". I didn't receive an email or anything for an interview/questions etc and had no idea I'd been hired really, no communication at all. You select your state and then click clinics you'd like to be considered for. There's supposed to be an email sent out every Monday with all the new available clinics (I've never received one), I just check the website. You'll get an email if you're picked for a clinic. The email says confirm via email that you want to accept that clinic and then you call and confirm with the coordinator at the site you're doing the clinic. 3 and 1 day prior to the clinic you receive a confirm text or call.
When you get to the site they should have the box containing all your supplies. You set up and give shots. Giving the shots is pretty straightforward, I hadn't used this certain needle before but, it was simple. All the training was done by a PDF document (I think a video would've been nice). Like JoJo said above the paperwork can be funky. Also, from what I experienced, what the training/paperwork says and how things really are can be different/conflicting.
When you open the box of supplies it'll have the vaccine and all the supplies needed syringes, Band-Aids, alcohol swabs, gloves etc and it'll have a folder with the needed paperwork and instructions. My folder was missing some paperwork so, I had to call and they emailed over the needed forms and a manager at the site printed them out. The actual work is fine, giving the shots is straightforward and easy. My clinic was just a few hours and in those few hours I gave a handful of shots. The manager said most of his employees came in after the clinic was scheduled and said he was trying to get people in earlier. Near the end of the scheduled clinic is when everyone started coming in. There's a paper in the folder that said in bold all uppercase print that said, you must stay and vaccinate everyone even if you have to stay longer than the clinic is scheduled and you can't leave until the on-site staff let's you go. I did most of the vaccinations for over an hour past the time my clinic was supposed to end. When I finished everyone waiting the manager said he had 2 more people coming on their way but, would be a few minutes. I called OccuVAX and asked them what to do since there were 2 people left and they said I should of packed up and left at the scheduled time because, this certain company won't pay for people to stay over and I was kind of "scolded". No where in any of my paperwork, emails or communications was I told this. All I had was the paper with the big bold letters that said I must stay and finish even if it's after my scheduled time. Well, anyways those last 2 people came while I was in the phone with OccuVAX and they said the finish them up.
Some of the things from the paperwork/training packet are different than what you receive. The sharps container return instructions were completely different than the instructions in the paperwork. A certain form said it'd be blue in the paperwork but, it was yellow. That plus the missing forms made things a little confusing but, was simple to figure out. After the end of my clinic I packed everything up and made a trip to the post office and to the other side of my town to UPS to drop the return packages off.
I know this is a long post but, I wanted to give my experience since there's not that much info out there. If you don't mind the minimal communication, training, kind of vague and conflicting instructions etc I think it could be an okay sometimes job for some people. I had fun setting up my table and enjoyed giving the injections and talking to people etc. If you're a person who needs a little more instruction, it's probably not the job for you. I don't think I'd have liked doing it as a new grad. Personally, I don't know if I'd sign up again next year. Being scolded for doing exactly what my paperwork told me to do plus the uncertainty if I'll get paid for that time has kind of turned me off. The drive to UPS was on my own time as well. I wouldn't say it was a bad experience, just kind of meh.