I can ask at work tomorrow who we use.
There is one other caveat which we experienced. Do not go to your regular doctor for shots. They have to disclose to the insurance companies the reason for the shots and where you are going. Your rates then increase depending on where you have visited. Go to a clinic.
Edited to add:
Checked and we use Medex. Maybe you should call them about the WA restrictions.
https://www.medexassist.com/ppcindividual.cfm