A Chinese pharmaceutical company has injected hundreds of thousands of people with experimental Covid-19 vaccines, as its Western counterparts warn against administering mass vaccinations before rigorous scientific studies are complete. China National Biotec Group Co., a subsidiary of state-owned Sinopharm, has given two experimental vaccine candidates to hundreds of thousands of people under an emergency-use condition approved by Beijing in July, the company said this week. Separately, Chinese drugmaker Sinovac Biotech Ltd....