We'll probably need a booster every 3 months from now on
Haha. I keep on thinking that the virus won't change much more, and I keep being wrong.
I will say that modeling teams had predicted previously that this particular combination of mutations would be particularly bad. And they didn't predict something else. So that gives me hope that this is some sort of "optimum" and there'd have to be a more dramatic shift to get immune escape from here.
So I still think there's some hope that the antigenic drift will taper off for this coronavirus. It really is nothing like flu. Antigenic drift and antigenic shift are complicated topics, but there are things that differ between the influenza and coronavirus that make them distinctly different and I'm not sure that we should expect annual boosters long term.
If we do, so be it. But I think it's going to be a bit different than influenza once things settle out. At a minimum, it seems that efficacy will likely be much better than it is for the influenza vaccine.
All speculation though. It's very hard to get a deep dive from an expert, in layman's terms, into the ways in which these viruses differ, but one difference we've discussed previously is the segmented influenza genome. Is reassortment still possible with coronavirus? Maybe. But it's not as common or likely as I understand it (it can happen though:
Co-infection of MERS-CoV and SARS-CoV-2 in the same host: A silent threat).
Again, from Wikipedia, SARS-CoV-2 does not have a segmented genome (it has a "has a linear,
positive-sense, single-stranded RNA genome about 30,000 bases long"), and it has a proofreading mechanism ("One of the proteins specified by the coronavirus genome is a non-structural protein, nsp14, that is a 3’-to-5’ exoribonuclease (ExoN). This protein resides in the protein complex nsp10-nsp14 that enhances replication fidelity by proofreading RNA synthesis, an activity critical for the virus life cycle."):
www.ncbi.nlm.nih.gov
For influenza:
"reassortment accelerates the rate of acquisition of genetic markers that overcome adaptive host barriers faster than the slower process of incremental increase due to mutation alone. The emergence of new influenza genes in humans and their subsequent establishment to cause pandemics have been consistently linked with reassortment of novel and previously circulating viruses"