Currently, I'm working with a non-profit in Los Angeles, CA, USA. It makes no sense for any medical professional to 'travel' to help with vaccinations. In all vaccine sites, it's local medical personnel. This is 2 of many reasons, licensing and liability insurance. Also, why would a person leave their city to travel to another city to vaccinate? Why would anyone hire a Chicago nurse to travel to Los Angeles to vaccinate when we have thousands of RN's, LVN's, MA's, EMT-P here? Or why would a volunteer travel from New York to Los Angeles, when there's tons of clinics there that need help.
But be aware, there are tons of volunteers from an organization that takes students from all over the USA to come to Los Angeles or a designated city to volunteer. They do it for school credit, resume and life experiece. And I think it's up to 3 months. They all need to stay at a designated dorm style accommodations set up with this volunteer organization. They are the only group I know of that travels to volunteer.