I came across an article few days ago, while checking the number of canditates for vaccines about COVID-19 where Sinopharm's vaccine development's trial phase caught my eye. The article says that:
In mid-July, Sinopharm launched its phase three trial among 15,000 volunteers—aged 18 to 60, with no serious underlying conditions—in the United Arab Emirates. The company selected the UAE, as it has a diverse population with approximately 200 different nationalities, making it an ideal testing ground.
Now, my question is, why is a diverse population present in UAE or any country with 150+ nationalities ideal for the testing phase of COVID-19? Is it because of the presence of diverse gene pool among the canditates from so many different nationalities? I don't understand why does testing on a population with approx. 200 different nationalities matter. Since, everyone's DNA is different, wouldn't they get the same results if they test it on a large sample space of population whose nationality is the same (for 2-3 generations or more)?