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Project #39:
Effect of pre-exposure use of hydroxychloroquine on COVID-19 death in patients with rheumatoid arthritis or systemic lupus erythematosus.


This is the first study, to our knowledge, to investigate the ongoing routine use of hydroxychloroquine and risk of COVID-19 mortality in a general population. In this study, which uses a database that includes around 40% of the population of England, we investigated whether routine use of hydroxychloroquine before the COVID-19 outbreak (ie, pre-exposure) prevented COVID-19 death.

We found no evidence to support a substantial benefit of hydroxychloroquine in preventing COVID-19 death. At the same time, we have shown no evidence of harm. The absence of clear harms or benefits would therefore support ongoing clinical trials using hydroxychloroquine.


  • Study leads: Christopher Rentsch
  • Organisation: University of Oxford and London School of Hygiene and Tropical Medicine