They already have a pretty high vaccination rate. Many older people did not get the covid vaccine simply because they didn't want to get it or because they felt no urgency to get it in the first place. Ironically, the vaccination rate has been quite high recently (though unfortunately, it'll be too late for many people). You could say that were suffering from their success of zero-covid during the first couple of years. Fact is that with how infectious Omicron is, dynamic-zero was never going to be sustainable. It was also economically unsustainable, several cities could no longer afford their containment measures and people had to pay for their own PCR tests.