see this

https://www.washingtonpost.com/world/middle_east/uae-sinopharm-third-dose/2021/03/21/588fcf0a-8a26-11eb-a33e-da28941cb9ac_story.html

 "DUBAI — A "very small number" of people in the United Arab Emirates are being invited to receive a third shot of the Sinopharm coronavirus vaccine after antibody tests indicated they did not have a sufficient immune response following two doses of the Chinese-made vaccine, its distributor confirmed Sunday. "

............

"The UAE has distinguished itself with an aggressive vaccination program that initially used Sinopharm, which conducted Phase 3 trials in the country, and was later expanded to include Pfizer-BioNTech, AstraZeneca and Russia’s Sputnik V."