Want to see something that’ll make your jaw drop? Do a web search on mnra vaccines back in 2019. There were a number of articles saying it was an exciting technology that would be available in possibly 5 years, but there were currently a number of issues to overcome.
Less than 2 years later, it’s been injected into a billion people.
Contacting and recovering from the Covid does build up immunity. For some people though their risk factor does not make that the best means of doing so. This is true for any virus.