PRINCIPLE nationwide Covid-19 clinical trials

About the trial

The PRINCIPLE trial platform is a national priority trial to find treatments for COVID-19. It is now a country-wide trial, and the only national priority platform trial in primary care. 

The trial is designed to test a range of treatments in the community, with treatment arms that can be stopped, replaced or added.

PRINCIPLE is currently evaluating usual care alone versus usual care plus azithromycin; or usual care plus doxycycline. Azithromycin is a commonly used antibiotic that is anti-inflammatory, treats community-acquired pneumonia and bacterial chest infections, and has antiviral properties. Doxycycline is another commonly used antibiotic.

The trial is being run by the University of Oxford and is funded by UK Research and Innovation and the Department for Health and Social Care through the National Institute for Health Research.

Aim of this trial: 

We aim to find treatments for COVID-19 for people in the community who are at higher risk of complications. We want to find medicines that can help people get better quickly and stop them needing to go to hospital. 

Who can take part

Participation is entirely voluntary. It is up to you to decide whether to take part in the trial or not.

The decision to not take part will not affect the standard of care you receive from the NHS in any way, now or in the future.

To take part, you need to be:

1. Experiencing symptoms that are likely to be caused by a COVID-19 infection, for fewer than 15 days:

  • a new continuous cough - this means coughing a lot for more than an hour, or 3 or more coughing episodes in 24 hours (if you usually have a cough, it may be worse than usual)​,
  • high temperature - this means you feel hot to touch on your chest or back (you do not need to take your temperature)​,
  • a loss of, or change in, normal sense of taste or smell


2. You have had a positive test for COVID-19 infection which was taken fewer than 15 days ago, AND are unwell with symptoms of COVID-19. These symptoms may include, but are not limited to:

  • shortness of breath,
  • general feeling of being unwell,
  • muscle pain, diarrhoea,
  • vomiting, fever and cough,

and you must have had them for fewer than 15 days.

The study is for people with ongoing symptoms. People who feel they are already well on the way to recovery should not take part.

3. You also need to be aged over 65 or aged 50 to 64, with at least one of the following conditions:

  • weakened immune system due to a serious illness or medication (e.g. chemotherapy)​,
  • heart disease or high blood pressure​,
  • asthma or lung disease​,
  • known diabetes,
  • liver disease,
  • stroke or neurological problem​.


What is a continuous / persistent cough?

A new, continuous cough means coughing a lot for more than an hour, or 3 or more coughing episodes in 24 hours (if you usually have a cough, it may be worse than usual).


How do I tell if I have a high temperature without a thermometer?

A high temperature means you feel hot to touch on your chest or back (you do not need to measure your temperature).

We are currently evaluating:

  • Usual care alone  or
  • Usual care + azithromycin (a commonly used antibiotic) or,
  • Usual care + doxycycline (a commonly used antibiotic)

Anyone experiencing COVID-19 symptoms, which started within the last 14 days may be eligible to join the PRINCIPLE trial if they are aged over 65or over 50 with an underlying health condition.

Alternatively you can contact the trial team directly: • 0800 138 0880

Further information

The Participant Information Sheet provides further details about this trial.

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