Does this treatment you can't get include vaccinations? I'm not sure what you're getting at. Anyway, hydroxychloroquine is on the list of World Health Organization Model List of Essential Medicines.[0]
It's a widely available drug that can be found even in remote parts of Africa and India where malaria is prevalent.
[0]https://apps.who.int/iris/bitstream/handle/10665/325771/WHO-...