Angiotensin receptor blockers have no effect on the severity of infection in people with COVID-19. People who need these medications for prevention can take them with confidence knowing there will be no impact on COVID-19.


Before the CLARITY trial, angiotensin receptor blockers were, and remain to be, a group of medications widely used to treat conditions including high blood pressure, kidney disease and heart disease. However, there was evidence to suggest that angiotensin receptor blockers may be able to limit the effect of the COVID-19 virus on the body.


The CLARITY trial was a pragmatic, adaptive, multicentre, phase 3, randomised controlled trial. Its main objective was to determine whether disrupting the renin angiotensin system with angiotensin receptor blockers will improve clinical outcomes in people with COVID-19.

CLARITY was led and coordinated by the NHMRC Clinical Trials Centre, The University of Sydney, in collaboration with The George Institute of Global Health, India. The study was funded by a competitive MRFF research award and by the University of Sydney. CLARITY recruited 787 participants from India and Australia in 18 months


787 participants from two countries

  • India - 778 participants
  • Australia - 9 participants


This Bayesian adaptive sample size design ensured that angiotensin receptor blocker use for COVID-19 was addressed in a timely manner with sufficient power while minimising resource use, highlighting the role for adaptive trials to accelerate evidence generation.


The research trial showed that angiotensin receptor blockers do not improve outcomes in patients hospitalised with mild COVID-19 but shows no overall evidence of harm over the 28 days of treatment. As most people who participated in the study had mild COVID-19 infection, the benefits in moderate or severe disease are less clear and are being investigated with a different group of participants in a separate study.

Our study findings suggest that people can continue to use angiotensin receptor blockers if needed for other health issues, and that these medications will not reduce the severity of a mild COVID-19 infection.


May 2020 - November 2021


The George Institute of Global Health, India.


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