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Favipiravir to be investigated as a possible COVID-19 treatment for at-home recovery in the PRINCIPLE trial

The antiviral drug favipiravir will be investigated as a treatment for COVID-19 in people recovering at home and in other non-hospital settings, in a clinical trial funded and supported by the NIHR.

The Platform Randomised trial of Interventions against COVID-19 In older peoPLE (PRINCIPLE) is one of the UK Government’s national priority platform trials of COVID-19 treatments, and the world’s largest currently taking place in community settings. 

The trial is evaluating a range of potential community treatments for COVID-19 to reduce recovery time and prevent hospital admissions and deaths. Favipiravir is the sixth medication to be entered into PRINCIPLE, and the first antiviral drug.

Eligible adults with COVID-19 symptoms can join the trial from anywhere in the UK, either online, over the phone or via a healthcare professional. So far 4,600 people have volunteered for PRINCIPLE since it launched in March 2020. 

PRINCIPLE is funded by the NIHR and UK Research and Innovation, and supported by the NIHR Clinical Research Network as a prioritised urgent public health study. 

Led by University of Oxford researchers, PRINCIPLE was set-up with the intention that drugs shown to have a clinical benefit could be rapidly introduced into routine NHS care. 

Favipiravir is an antiviral drug that has been licenced in Japan since 2014 to treat influenza. It works by inhibiting a viral enzyme called RNA polymerase, preventing viral replication within human cells. This viral enzyme is common to several viruses, including SARS-CoV-2, which causes COVID-19.

The drug has shown positive results against SARS-CoV-2 in laboratory and animal studies, with small pilot studies in humans demonstrating some benefit in reducing symptoms and the duration of illness.

PRINCIPLE trial Co-lead Investigator, Chris Butler, said “Viruses need human cells to multiply and survive, and favipiravir blocks the complicated molecular dance that happens between a virus and our own cells when the virus is replicating. This is the first drug we will be testing that was designed specifically to target viruses, so we are particularly excited to be including favipiravir in the PRINCIPLE trial to determine whether it could be used in the community as a COVID-19 treatment and prevent people from getting very sick.”

The decision to add favipiravir to the trial was made by the University of Oxford researchers and trial steering committee leading the trial in conjunction with the Chief Medical Officer, following a recommendation by the UK COVID-19 Therapeutics Advisory Panel. 

The trial is supported by the NIHR and a vast network of health and care professionals in care homes, pharmacies, NHS 111 Hubs, hospitals and more than 1000 GP practices across England, Wales, Scotland and Northern Ireland. 

Read our case study about the PRINCIPLE trial