JOHANNESBURG — The detection of the Omicron variant in Africa signals the next stage of the battle against Covid-19: getting many more people inoculated in poorer nations where vaccines have been scarcest in order to deter new mutations from developing.

But while world leaders sometimes talk about this as if it were largely a matter of delivering doses overseas, the experience of South Africa, at least, hints at a far more complex set of challenges.

Like many poor countries, South Africa was made to wait months for vaccines as wealthier countries monopolized them. Many countries still do not have anywhere near enough doses to inoculate their populations.