Favipiravir has been added to the list of community-based medications being investigated as potential Covid-19 treatment that can be taken by patients at home.

Researchers at Oxford University have added the antiviral drug favipiravir to the PRINCIPLE trial — a nationwide study launched in March of last year — which tests the effectiveness of therapies available in primary care to potentially speed up the recovery of Covid patients and prevent hospital admission.

The antiviral has been used to treat influenza in Japan since 2014 and is also being used to treat other viral infections. The drug works by inhibiting a viral enzyme which in turn prevents the virus from replicating itself within human cells.

So far, small pilot studies in both humans and animals suggest the drug is effective at reducing symptoms of Covid and the duration of illness.

Favipiravir is the sixth medication and the first antiviral to be tested in the PRINCIPLE trial, joining budesonide, an inhaled steroid typically used for treating lung inflammation, and colchicine, an anti-inflammatory drug traditionally used for treating gout.

Earlier this year, researchers removed two antibiotics azithromycin and doxycycline from the trial, after it was found they were ‘not generally effective’.

Hydroxychloroquine was suspended in June after researchers retracted a paper that had indicated the treatment was unsafe.

However, the trial into the impact of hydroxychloroquine continued in June, after researchers retracted the paper that had indicated the treatment was unsafe.

Commenting on the recent addition to the trial, Chris Butler, PRINCIPLE trial co-lead investigator, 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.

‘Until now, we have been testing medicines that have not typically been used to treat viral infections.

He added: 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.’

Gail Hayward, PRINCIPLE trial co-investigator, said: ‘Even with the successful vaccine rollout, it’s the combination of vaccines, testing and treatments that will bring an end to this pandemic.

‘There still isn’t a safe and effective therapeutic for Covid-19 that we know for sure will prevent people needing to go into hospital for treatment. By joining the PRINCIPLE trial, people with coronavirus symptoms could play a vital role in helping to transform C-19 into an illness that can potentially be treated by your regular general practitioner,’ she said.

The trial is currently open to people who are aged over 50 living with comorbidities, and to anyone over the age of 65. Those with Covid-19 symptoms can join online from home or via GP practices across the country, without needing face-to-face consultations.