I would say that for a vaccine to be open source there should be exact instructions on how to create it along with a justification for each step, it should list

I would say that for a vaccine to be open source there should be exact instructions on how to create it along with a justification for each step, it should list the exact contents of the vaccine (preservatives, etc), as well as any genetic code included (along with a justification for each part of it). In addition it should be legal for someone to create their own vaccines by following said instructions. The part regarding legality of making your own copies would help with the vaccination of poor regions such as africa, while transparency could be used by researchers in order to find ways to improve it, or to create new vaccines for other viruses, or for students to learn more about it. In addition it would increase the trust of the general public for the vaccine.