Study of NHS Frontline Workers to Investigate if Seaweed Could be Used in Preventing COVID-19

Human clinical trial carried out by Swansea University follows successful laboratory study on iota-carrageenan

Monday 30th November 2020: A research study involving 480 frontline NHS workers is underway by Swansea University to investigate the efficacy of Boots Dual Defence in preventing COVID-19 illness and reducing the severity of COVID-19 symptoms.[i]

Boots Dual Defence, which contains Carragelose, a patented version of iota-carrageenan, is already clinically proven to help shorten the duration and severity of cold and flu-like symptoms,[ii] and new in-vitro (test tube) laboratory study results suggest that Carragelose could also reduce the risk of an infection with SARS-CoV-2, the virus which causes COVID-19.[iii] [4,5]

These promising results will be further validated in a new clinical trial, ICE-COVID, which will investigate whether Dual Defence can either prevent COVID19 infection entirely, or reduce severity of symptoms in humans compared with placebo.

Carragelose is a patented version of iota-carrageenan and is generated from consumable red seaweeds occurring naturally throughout the world. The ingredient is exclusively available in Boots Dual Defence Nasal Spray in the UK and Carragelose is patented and invented by Marinomed in Austria. It acts as a barrier by forming a gel to trap cold and flu virus particles as they enter the body, therefore reducing the likelihood of infection or reducing the amount of virus entering the body and therefore reducing the severity of symptoms.

Professor Ron Eccles, cold and flu expert and former director of the Common Cold Centre at Cardiff University is co-investigator on the research study, and will work closely with the Chief Investigators at Swansea University, Professor Iain Whitaker, Surgical Specialty Lead for Health & Care Research Wales, and Professor Hayley Hutchings, Co-Director of the Swansea Trials Unit.

Dr Zita Jessop, Principal Investigator for the clinical trial and clinician scientist at Swansea University, said:

"After seeing the effects of this pandemic on colleagues caring for patients with COVID-19, we wanted to find a way for research to help protect frontline NHS staff. Previous studies highlighted the effectiveness of iota-carrageenan-based nasal sprays against coronaviruses, indicating promise against SARS-Cov-2. If the results of this randomised placebo-controlled clinical trial are positive as we expect, this has the potential to add an extra prevention strategy in the fight against COVID-19."

Richard Evans, Executive Medical Director, Swansea Bay University Health Board added: 

"We’re delighted that Swansea Bay University Health Board is able to contribute to this research. Although the prospect of effective vaccines is now on the horizon, it’s still vitally important that we explore all opportunities to investigate new treatments for COVID-19 and we’re pleased to be playing a part in that global effort."

It is anticipated that the results of ICE-COVID will be published in March 2021.


[i] ClinicalTrials. Gov Last Accessed: November 2020.
[ii] Eccles R., Iota-Carrageenan as an Antiviral Treatment for the Common Cold. Open Virol J 14, 9 (2020).
[iii] Eccles, R., et al. Efficacy and safety of iota-carrageenan nasal spray versus placebo in early treatment of the common cold in adults: the ICICC trial. Respir Res 16, 121 (2015).
4 Morokutti et al. 2020: SARS-CoV-2in-vitroneutralization assay reveals inhibition of virus entry by iota-carrageenan (
5 Bansal et al. 2020: Iota-carrageenan and Xylitol inhibit SARS-CoV-2 in cell culture (


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