No, "we" haven't "known", and I'm not sure oversimplification is a good answer to fear mongering. Yes, expert consensus has been positive from almost day one,

No, "we" haven't "known", and I'm not sure oversimplification is a good answer to fear mongering. Yes, expert consensus has been positive from almost day one, based on SARS-Cov-1 and other coronaviruses. Still, what we didn't know (and in some cases still don't): * Is there anti-body dependent enhancement? * Effects on/from variants? * Effects from other coronaviruses? * Role of severity of infection on protection? * Clinical relevance of protection * Epidemiological relevance of protection * Mechanism of protection * Duration of protection etc. BTW in most of Europe, recovered persons are on equal footing with the tested and vaccinated.