Why Covid-19 outbreaks in countries using Chinese vaccines don't necessarily mean the shots have failed

Countries using vaccines from China are still seeing high caseloads. That's prompted questions about those vaccines' efficacy.

What links these countries is that they have each fully inoculated more than 50% of their populations, largely with Chinese-made coronavirus vaccines. And that's raised questions over the vaccines' efficacy. If the Chinese vaccines aren't working, that's a huge problem -- and not just from a health perspective. Beijing has staked its reputation on providing other countries with vaccines.