There have been studies which claim that prior infection by SARS1 (2003) has conferred some immune protection against SARS2 (2020). That would be 17 years, not 180 days.

With billions of dollars at stake on multiple sides of proposed policy, there is sufficient financial incentive to study very closely the mechanisms of both natural and artificial immunity.

Policy makers can selectively highlight or ignore science, but not forever. In the US, some early policies were overturned by later court rulings, as data became available for lawsuits.