Dad, 78, took two doses of the chinese covid19 sinopharm vaccine two weeks ago, he can take astrazeneca now which is believed to be more effective. is it hazardous to do so?

Unfortunately, the efficacy and purity of the Chinese vaccine is indeed questionable, and is unlikely to provide protection. But not unclear if a severe immune interaction could occur if the AstraZeneca vaccine is added at this point. We have no clinical experience here, and the risk of complications is real. An immunologist or infectious disease specialist is needed at this point.

Not known yet. Sinopharm is a traditional-type vaccine like our annual flu shots, not a newer mRNA or viral-vector vaccine. Current data shows Sinopharm may protect 50-80%. Realize that China and India are highly advanced in science and EACH take care of 1.4 billion people in their countries. 80% protection means if 100 unvaccinated people catch COVID, only 20 Sinopharm recipients would catch it.