Since omicron just turned up in the U.S. (California), get boosted now. Don’t wait.
In the briefing I was in this morning, they said to definitely get the booster now. IF the new variant needs a new booster later on, then get that, but for now getting the booster is the best bet, not waiting until, perhaps, a new booster comes out for the new Xi…er, I mean Omicron…variant down the road. The booster should still mitigate the symptoms, even if you still get the virus, at least based on what they seem to know right now.
In regard to South Africa specifically, they have plenty of vaccine on hand*, and the bottleneck to greater vaccination % of the population is “uptake.” They are having different versions of the same problems we have: “hesitancy” primarily based on conspiracy theories and misinformation. (In their case, some of the conspiracy theories at least have some logical, historical grains of truth behind them.)
We do need to do more to help the less-well-supplied countries get what they need, both in terms of doses and infrastructure to deliver them, if needed. That should absolutely be a huge priority for all well-supplied countries. This is not a crisis we can solve just for ourselves, and even if it were, it would be wrong to take that approach.
*They had, at the time I read an article on it a few days ago, 16.5 million doses on hand. They were also asking for the delay of additional shipments that were ready for them. They wanted the delay so that they wouldn’t keep accumulating more and more surplus. So with regard to South Africa specifically, there is no need to worry about taking up a dose that should have been available there. (And, as others have said, there’s not such a direct, zero sum connection between doses at your pharmacy and availability to people in other countries.)