https://forums.bharat-rakshak.com/vi...7800&p=2501615

https://www.wsj.com/articles/bahrain...ne-11622648737

In a separate, unpublished, real-world study of Sinopharm in Serbia, 29% of 150 participants were found to have zero antibodies against the virus three months after they received the first of two shots of the vaccine. The average age of the people who participated in the Serbian study was higher than 65.