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PRINCIPLE trial finds no benefit from antibiotics, azithromycin and doxycycline for COVID-19 patients

Published: 25 January 2021

A NIHR-supported study investigating potential COVID-19 treatments that might be suitable for patients in the community has found that the commonly used antibiotics, azithromycin and doxycycline, do not reduce recovery time for patients.

Azithromycin and doxycycline were investigated as separate treatments in the PRINCIPLE trial to see if they help people with early stage COVID-19 to recover more quickly at home, or prevent the need for hospital admission. Both drugs are being used by some doctors in the hope of treating COVID-19 in the early stages of the disease.

Following interim analyses of data from both the azithromycin and doxycycline arms of the study, the independent Trial Steering Committee concluded that there is no beneficial effect in patients aged over 50 who are treated with either antibiotic at home in the early stages of COVID-19.

The researchers found that neither treatment reduces the time taken for people to first report that they feel recovered from COVID-19.

The PRINCIPLE study did not look at the effects of these drugs in patients admitted to hospital with COVID-19. However in December 2020, the NIHR-supported RECOVERY trial also reported no clinical benefit from azithromycin as a treatment for hospitalised patients.

The antibiotics have not been prescribed in combination in any patients in the PRINCIPLE trial.

Following the review of the data, the trial has therefore closed further recruitment to its azithromycin and doxycycline treatment arms.

Professor Nick Lemoine, Medical Director of the NIHR Clinical Research Network said:

“When this trial was designed, we really could not predict whether these antibiotics would be effective as treatments for less seriously ill patients within the community. These important results will now enable clinicians, scientists and researchers the world over to focus on alternative therapeutic options instead.”

“We want to thank every single person who has taken part in the PRINCIPLE study. This important research has contributed vital data which will once again advance the science around COVID-19.”

Professor Chris Butler from the University of Oxford’s Nuffield Department of Primary Care Health Sciences and Co-Lead of the PRINCIPLE trial, said:

“Azithromycin and doxycycline have anti-inflammatory, antibacterial and possibly antiviral effects, and so were considered as potential treatments for COVID-19 in the community. While we are completing the analysis of the full range of study outcomes, and in different patient groups, our findings show that a three-day course of azithromycin or a seven-day course of doxycycline has no important clinical benefit in terms of the time taken to feeling recovered, and so will not help most patients with COVID-19 in the early stages their illness.”

PRINCIPLE: Urgent public health research

The PRINCIPLE trial is jointly funded UK Research and Innovation (UKRI) and the NIHR. While, as a prioritised urgent public health study, delivery of the study is also supported by the NIHR Clinical Research Network and the devolved administrations - with 3,800 participants across the UK taking part so far.

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