"Booster shots" pseudoscience

Vaccine passports? Immunity can be obtained via vaccines, infections, and in 2021 even with a government issued document... But what happens to government-sanctioned immunity when the virus mutates? And why do people vaccinated (twice!) less than 6 months ago considering getting "a boost"? Would the vaccine passport require a boost as well? When does it expire??

(Uploaded Aug 2021 to YT)