California is not a sovereign nation and member of the UN. So CA cannot become a formal member of the WHO. There are 2 non-UN member territories that can join as associate members: Puerto Rico and Tokelau, upon application on their behalf by a responsible member state. While only sovereign states and associate members are formal members, sub-national entities (such as states, provinces, or cities) may participate in specific WHO networks, like the Global Outbreak Alert and Response Network (GOARN), through formal partnerships. California became the first US state to join GOARN in January 2026, following the US withdrawal from WHO.

Any decisions the WHO makes are only enforceable on member states. With the International Health Regulations (IHR) in particular, only the member states are legally bound by the IHR. That is why Trump got us out of there - to protect our sovereignty. Non-members are not required to follow WHO recommendations, including during Public Health Emergencies of International Concern (PHEIC). So basically, Newscum is pulling a publicity stunt for his base. All bark and no bite. In the end, it's just a symbolic move.