When you have no other choice Sinovac it is certainly much better nothing but must be boosted regularly. There are others choices in developed and developing countries.
HK Gov has talked to all the manufacturers of better vaccines and chosen not to buy them relying instead for some reason unknown on Sinovac. Even appearing to push Sinovac above known better products.
It is not Mar 2021 when the world was scrambling for protection. It is Mar 2022 when there is the ability to pick and choose the best options and have some in reserve.
Again data on how long since the last jab would be helpful. As it is being unvaccinated is a much higher risk but someone with Sinovac is ~twice as likely to as someone with Pfizer.