China really does not have a choice. Its main vaccine, made by Sinovac, isn't effective against Omicron [1]. Additionally, there is a large population of elderly people who are vulnerable with or without a vaccine. Same thing that happened in Hong Kong (death rate per million got to 3x the US' in its worst week) but in a scale 200x larger. Scary.
Some family members lived in Hong Kong when the Sinovac vaccine rolled out. There was hysterical reporting of suspected side-effects to the point that vaccine hesitancy was off the charts. Cultural norms are to take care of elders in your family, and few people wanted their parents/grandparents to get vaccinated.
Sinovac wasn't as effective as the mRNA vaccines, but it also wasn't killing people with side effects: quite a lot of Omicron deaths could have been easily prevented.
Sinovac is highly effective at preventing serious illness and death. In Hong Kong, 3x Sinovac turned out to be just as protective as 3x mRNA.
The problem in Hong Kong is that a large fraction of old people chose not to get vaccinated at all. Those that got vaccinated (including with Sinovac) had orders of magnitude less risk of death.
[1] - https://hongkongfp.com/2022/02/26/factwire-sinovac-limits-ho...