We do not have strong data on how long it takes someone to go from infection to symptoms, to inpatient then to final disposition due to all the moving parts of this epidemic.
As we try all sorts of different treatments, whether officially (clinical trials) or not, we need to know what the natural history of the disease looks like to see if a therapy has any effect -not really ethical for us to have a placebo control arm at this point, and there is no defined standard of care.
The problem is that no one group seems to have a large enough sample size, particularly to account for the moving effects of test availability, methods of treatments et c. that have changed so much over the past few months.
The large data and computing capacity here may allow for these “environmental” variables to be considered. Additionally, in the future in case there are any genetic variations which may cause some therapies work better than others that could also be examined.
The major thing is to get the “cleanest” description of the development of symptoms, progression and the development of complications and disposition of COVID-19 essentially providing the real world “control” data.
Happy to answer any questions/ discuss more.