“The patent IS protection for intellectual property. Its purpose is to assure the creator gets the benefit from his/her work.”
When the government pays, that enables the government to say, no IP protection on this one. IIRC, the US government dumped a substantial amount of money into this arena to get things moving, rather than the private pharmas having to front the costs.
More on this can be found at Upcounsel, and other IP-aware entities.
https://www.upcounsel.com/government-owned-patents