www.cnbc.com/2021/01/25/covid-vaccine-travel-seychelles-is-open-to-vaccinated-visitors.html Yes, it looks as though the Seychelles had next to no COVID until very recently, so very little pre-existing natural immunity; most likely, the zero-COVID countries (China, Australia, NZ, Vietnam etc.) will need to ensure high vaccination rates with a really effective vaccine, because there is little pre-existing immunity for the vaccines to mesh with. 62% jabbed with sino-vax crap probably isn't going to cut it.
As long as they vax with Pfizer, AZ or similar and manage to jab most people including a high percentage of kids, I am sure all countries will be fine.
China must be panicking a bit now. It does look like the sino-vaxes do not provide enough immunity to keep the virus at bay. Therefore, China has a choice of either using mostly foreign vaccines (=losing face) or allowing some spread of COVID within China after trumpeting China's zero-COVID credentials (=also losing face).