> This process can take years if the background rate of infection is low enough.
This is why the phase 3 trials tend to be organised in countries with high rates of infection, such as Brazil, South Africa or India. In locations with low rates of infection it's too likely that the people in the experimental group don't get infected simply because they don't get exposed to the virus.
This is why the phase 3 trials tend to be organised in countries with high rates of infection, such as Brazil, South Africa or India. In locations with low rates of infection it's too likely that the people in the experimental group don't get infected simply because they don't get exposed to the virus.