Did the experimental treatments wane, or did the experimental treatments cause the new strains?
If antibiotics are overused will you get resistant strains of bacteria? We all know the answer.
It looks like it waned. Here is study detailing it.
https://www.medrxiv.org/content/10.1101/2021.07.27.21261237v1
“The average half-life of NT50s was ∼68 days and the average time-length for participants’ serums to lose the detectable activity was ∼198 days. Although serums from elite-responders potently to moderately blocked the infectivity of variants of concerns, some serums with moderate NT50s failed to block the infectivity of a beta strain.
What that means is the half life of neutralizing antibodies is only 68 days and at 198 days nothing. So at around 6 mos you need a “booster” shot and on into infinity.
Both