Originally Posted by
rickair7777
Your immune system will retain T-cells (aka memory cells) which will quickly mobilize your system to make the right antibodies on-demand. So efficacy duration is a combination of factors, including t-cell memory and response time, in addition to lingering antibodies. So the only way to know for sure is to wait and see, although the mfgs probably have a rough idea by now based on the blood-chemistry of the early-stage trial volunteers. But even that's not even the entire story, they really will need to collect real-world clinical data, as opposed to making the call based on lab chemistry.
It's possible they might do a just-in-case booster before they know for certain, rather than risk lost efficacy in 100's of millions (billions?) of people.
You don't get T-cell memory with the vaccines, they are not encoding the actual Covid19 spike protein, especially not the variants, as the actual one is not stable for production. It's SARs2(6ZP1).
RCSB PDB - 6ZP1: Structure of SARS-CoV-2 Spike Protein Trimer (K986P, V987P, single Arg S1/S2 cleavage site) in Closed State They modified the virus spike protein to a stable version that has been studied for years.
Ideally, you want someone who is vaccinated to actually get Covid, as that produces a full immune response that lasts a long time. Maybe a future vaccine will change that, but for now, when the antibodies fade, there is no indication that your body will recognize the new Covid variants.