A. LIkely scenario
it means the double masks and the boosters did shit to prevent him being infected with the Wuflu.
Or B. The most likely scenario
Brandon is way too tired from his Middle East trip and is feigning COVID to stay out of the public eye.
Or C. The least likely scenario is
They are planning on using this to swap in Kamala
But the guy is way gone... The last public appearances were a completely disaster. "They" are accelerating the time-line.