You know how Luffy almost died due to getting poisoned by Magellan in Impel Down?
Well, it was stated that he received some immunity to poison afterward. That’s something he wouldn’t have had if he hadn’t gone through that. His immune system developed a defense against it.
That’s kinda how vaccines work. Looking deep into the rabbit hole of conspiracies and political jumbo jumbo isn’t gonna help you any.
People go to the doctor, get a vaccine, possibly feel bad the next day (because that’s a natural response) and feel better afterward.
Not everything is preventable with natural immunity. I don’t think we even have natural immunity for a lot of things. If we did, then why would vaccines exist in the first place?
It’s such a simple process that I don’t understand why a lot of people argue against it.