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The Co-Chief Investigators of the PRINCIPLE Trial, Professor Chris Butler and Professor Richard Hobbs, write an open letter to health professionals across UK primary care calling on their support, so those who are still contracting COVID-19 are given the opportunity to join the trial.

> Download the letter (.pdf)

The PRINCIPLE Trial needs the help of every GP, general practice, primary and social care professional in the country.

PRINCIPLE is the National NIHR Urgent Public Health Prioritised trial evaluating possible treatments for COVID-19 in primary care, and endorsed by the CMOs of all four nations. The trial aims to find out whether early treatment in the community speeds recovery and reduces the need for hospital admission for those with COVID-like-Illness.

PRINCIPLE will enrol patients with symptoms of COVID-19 for less than 15 days, (with or without a positive SARS-CoV-2 test), and:

  • Aged 50 or over with underlying health conditions.
  • Aged 65 and over, with or without underlying health conditions.

The trial started in a single practice on 1st April 2020. Since then, 833 general practices have been opened to recruitment through the NIHR Clinical Research Network across England and similar networks in the devolved nations, and more than 550 participants have now been randomised. The trial is integrated with the Oxford Royal College of General Practitioners Research and Surveillance Centre. Practices that are signed up and open to recruitment should please continue with existing processes. 

We urgently need more of those who are still contracting the disease to be given the opportunity to participate in the trial. Fortunately, this innovative study is now available to every eligible person throughout the UK, as patients can now also be recruited centrally.      

Every other GP practice, out-of-hours provider and NHS 111 across the country can now contribute by identifying and signposting patients to the study. Please direct potential participants aged 50 and over with symptoms of COVID to self-screen via the website ( The study team can also help people navigate participation by telephone, if this is preferred: They should call 0800 138 0880 for telephone support.

When participants consent to participate in the trial, the trial team may contact their general practice to ask for information for confirming eligibility for the study. The practice can send the trial team an invoice on practice headed paper for £50 per participant in recognition of this contribution.  No contract is needed for this. Please could all GPs contacted by the study team help them with eligibility checks as soon as you are able to do so.

Patients are generally very pleased to be offered the opportunity to participate in this critically important research and are keen to be able to provide information about their illness for the greater good.

Every patient included in the study will be a massive contribution to our discipline’s flagship PRINCIPLE Trial, and will be one step closer to generating sorely needed evidence to find treatments for COVID-19 and underpin the best possible care we can give to our patients.  

PRINCIPLE is funded by UK Research and Innovation and the Department of Health and Social Care through the National Institute for Health Research.