None of the current vaccines are particularly effective, and far from what we had hoped for. They are poor at stopping the spread and only offers heightened immunity for a short period (relatively, hence why many people are given 2, 3, 4 doses).
It doesn't seem realistic for China to vaccinate a billion people with their rudimentary health care system (especially outside the major cities). They could focus on just the elderly/weak but even that is a huge task and it's too late now in this giant wave. It might prevent some hospitalisations and deaths but at a high cost. We need much better vaccines against the current omicron variants and hope new ones won't emerge.
Covid-19 is no longer a pandemic. It's endemic. Vaccinating billions of people every 6-8 months globally is not viable. I think future vaccines will either be superfluous because of widespread immunity in the general public, or only used for the elderly/immunodeficient, akin to influenza vaccines. But they need to improve them.
The biggest concern right now is new, more lethal variants, and the more people infected the more likely it is for new variants to arise. That can change everything.