One other consideration is that Omicron is significantly milder than previous variants

Perhaps there's a fear that an Omicron targeted vaccine would allow a more deadly variant to take over again

Omicron branched off the original lineage IIRC, not Delta nor Beta. So, no, we can’t make that assumption.

I'm not saying it's a certainty, just a strong likelihood.

> Therefore I can't imagine how a vaccine targeting the original spike protein would be expected to be more effective than one targeting the spike protein from Omicron against new variants.

Well, besides imagining, we're also doing science, so what does the data that you've seen say?

Is there data out there comparing variant-specific vaccines to the original in their effectiveness against derivative variants? I haven't seen anything like that.

Perhaps there is a reason the original vaccine would be expected to be more broadly effective, as my parent said. It's not intuitive to me, but that doesn't mean it's wrong. Hence my question.

My point was that our human body doesn't work by rhetorical reasoning or intuition. There are often things we discover about our immune system that are counter intuitive - for e.g. Using specially developed & formulated vaccines to teach the body to suppress immune response towards antigens (via Treg cells), rather than to neutralize them which is what most vaccines aim to do.

Specifically I was objecting to "Given X, we wouldn't expect Y to happen" aspect of your argument. Its never so simple with the human body! It works in many other domains, and so as a former programmer myself I have to catch myself trying to apply such reasoning to biological systems which can't be modeled like that.

Let's say we wait until only 1 out of 10000 cases world-wide is caused by a non-Omicron strain. Then, an Omikron-specific booster would be worth it. Otherwise, we are just playing whack-a-mole with other strains.

What if we had multivalent mRNA vaccines like the HPV vaccine? Gardasil first covered three different strains, then later was bumped to nine, hence Gardasil-9. It doesn’t have to be all or nothing.

HPV viruses are DNA viruses, which means they evolve way slower than Corona viruses. This makes it easier to identify strains that are worth developing a vaccine against. Also, the mRNA technology and/or the production lines are probably not yet capable of producing multivalent vaccines.

A quick Google for "multivalent covid vaccine" shows trials in progress and articles from as early as 2021, so I'd say there's progress happening here.

Good news!!

There are some in development, but they don't use mRNA.

https://www.technologynetworks.com/vaccines/articles/the-hun...