Our lab continues to explore the body of studies (all 3 types: Interventional, Observational and Registries).
See a plot here
https://github.com/lhncbc/r-snippets-bmi/blob/master/regCOVID/Count_Studies_Over-Time.png
repo link https://github.com/lhncbc/r-snippets-bmi/blob/master/regCOVID
(and relevant other link is COVID-19 Registered Trials - and analysis - The Centre for Evidence-Based Medicine )