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Antiviral drug Molnupiravir shows activity in those vaccinated and unvaccinated against COVID-19

Published: 20 October 2022

The latest results from the AGILE platform have shown evidence of antiviral activity (faster clearance of virus) from the drug molnupiravir in both vaccinated and unvaccinated people with a broad range of COVID-19 variants.

The results of the trial have been published in The Lancet Infectious Diseases.

AGILE is a consortium comprising the NIHR Southampton Clinical Trials Unit, NIHR Clinical Research Facilities across the UK (including Southampton CRF), Liverpool School of Tropical Medicine, and other partners, and is led by the University of Liverpool.

The antiviral drug molnupiravir received regulatory approval in November 2021 for treating people with mild to moderate COVID-19 who are at increased risk of developing severe disease. These approvals were based solely on data from unvaccinated individuals which showed the drug was effective at reducing the risk of death and hospital admissions in those at highest risk of severe COVID-19. But uncertainty as to the effectiveness of molnupiravir in a highly vaccinated populations has limited its use in a wider population.

“In a constantly changing pandemic, it is essential to understand if drugs remain effective in today’s population with the circulating variants we encounter” says Professor Saye Khoo, Chief Investigator for AGILE. “We observed an antiviral effect in both vaccinated and unvaccinated people, infected with variants including Delta and Omicron. What we do not yet know is how much of this antiviral benefit translates into clinical benefit – since risk of severe COVID-19 depends on factors such as the immune system, concomitant diseases and host characteristics”

The AGILE team initially undertook a Phase I trial of molnupiravir, evaluating a range of dosing in order to determine the optimal dose of molnupiravir for treating COVID-19. These data (published last year) were shared with the manufacturers Merck who subsequently undertook their pivotal late-phase licensing trial in unvaccinated patients.

AGILE meanwhile continued with this phase II trial in the wider population of both vaccinated and unvaccinated patients, enrolling across the NIHR Clinical Research Facilities in Liverpool, Southampton, Manchester, Lancashire and London.

Professor Gareth Griffiths, Director of the Southampton Clinical Trials Unit, says: “The results from this trial do not contradict the existing evidence of a moderate benefit from molnupiravir. We shared our trial findings with colleagues in Oxford who are coordinating the PANORAMIC trial, a much larger study in a highly vaccinated population, which will help add further evidence to the potential benefits of molnupiravir.”

Samples collected from participants in the AGILE trial are now being analysed in the laboratory to gain a better understanding of which patients and COVID-19 variants molnupiravir can be most effective for and in the hope that it is a suitable a drug for everyone in the community to access as soon as they are found to have COVID-19.

Professor Griffiths continues: “Following on from these positive results, the AGILE platform is moving forward with its next trial to see whether a combination of two antivirals, molnupiravir and Paxlovid, can be even more effective in combatting the COVID-19 infection, and we expect to open to recruitment in Southampton and other CRFs later this month”.

Notes for editors

AGILE Candidate-Specific Trial 2 (CST-2): A Randomized, Multicentre, Seamless, Adaptive, Phase I/II Platform Study to Determine the optimal dose, Safety and Efficacy of EIDD-2801 for the Treatment of COVID-19.

AGILE is an academic clinical trial platform led by the University of Liverpool and the NIHR Southampton Clinical Trial Unit, in partnership with researchers from the Liverpool Tropical School of Medicine and NIHR Liverpool and Broadgreen Clinical Research Facility. It has been established to enable the rapid clinical evaluation of potential COVID19 therapeutics across the UK CRF Network. Visit the AGILE website.  

The Southampton Clinical Trials Unit (SCTU) is a National Institute for Health Research (NIHR) supported CTU with expertise in the design, conduct and analysis of multicentre, interventional clinical trials. The CTU is based within the University of Southampton with offices at the University Hospital Southampton NHS Foundation Trust Southampton General Hospital site. Visit the SCTU website

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