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 r-snippets-bmi/regCOVID at master · LHNCBC/r-snippets-bmi · GitHub
(and relevant other link is COVID-19 Registered Trials – and analysis | The Centre for Evidence-Based Medicine )