There are two answers to this. The first is that he's lying, the second is that he's hopelessly incompetent at his job.
“...he doesn’t have an idea if natural immunity exists or not?”
We’re back to what “it” is.
Natural immunity cannot exist as long as there is no way to destroy the virus. This is why people are getting sick more than one time. The virus isn’t dead and it can attack the body again and again until the body can clobber all of it in each attack. The vaccines are not designed to do that and it takes a long time for one body to create its own immunity.
To give you an idea, there are still outbreaks of the bubonic plague in the US every year. This virus today is the one that hit San Francisco in 1900 and has stayed the same and morphed to something different in other strains. It ain’t dead, Jim. It, in a lot of cases, just changed it clothes.
It is already clear, however, that the virus is changing too quickly, new variants are spreading too easily and vaccination is proceeding too slowly for herd immunity to be within reach anytime soon. Maybe never. Me, possibly never.
A good article:
https://www.yalemedicine.org/news/herd-immunity
wy69
Fauci and the rest want to make people forget what natural immunity is and block access to other known, inexpensive, and effective treatments. The idea is to present the vax (plus boosters ad infinitum) as the only of dealing with the rona.