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A study protocol for a double-blind randomised placebo-controlled trial evaluating the efficacy of carrageenan nasal and throat spray for COVID-19 prophylaxis—ICE-COVID

Jessop, Z. M., Gibson, J., Lim, J. Y., Jovic, T. H., Combellack, E., Dobbs, T. D., Carter, K., Hiles, S., Islam, S., Healy, B., Humphreys, I. ORCID:, Eccles, R. ORCID:, Hutchings, H. A. and Whitaker, I. S. 2022. A study protocol for a double-blind randomised placebo-controlled trial evaluating the efficacy of carrageenan nasal and throat spray for COVID-19 prophylaxis—ICE-COVID. Trials 23 (1) , 782. 10.1186/s13063-022-06685-z

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Introduction: At present, vaccines form the only mode of prophylaxis against COVID-19. The time needed to achieve mass global vaccination and the emergence of new variants warrants continued research into other COVID-19 prevention strategies. The severity of COVID-19 infection is thought to be associated with the initial viral load, and for infection to occur, viruses including SARS-CoV-2 must first penetrate the respiratory mucus and attach to the host cell surface receptors. Carrageenan, a sulphated polysaccharide extracted from red edible seaweed, has shown efficacy against a wide range of viruses in clinical trials through the prevention of viral entry into respiratory host cells. Carrageenan has also demonstrated in vitro activity against SARS-CoV-2. Methods and analysis: A single-centre, randomised, double-blinded, placebo-controlled phase III trial was designed. Participants randomised in a 1:1 allocation to either the treatment arm, verum Coldamaris plus (1.2 mg iota-carrageenan (Carragelose®), 0.4 mg kappa-carrageenan, 0.5% sodium chloride and purified water), or placebo arm, Coldamaris sine (0.5% sodium chloride) spray applied daily to their nose and throat for 8 weeks, while completing a daily symptom tracker questionnaire for a total of 10 weeks. Primary outcome: Acquisition of COVID-19 infection as confirmed by a positive PCR swab taken at symptom onset or seroconversion during the study. Secondary outcomes include symptom type, severity and duration, subsequent familial/household COVID-19 infection and infection with non-COVID-19 upper respiratory tract infections. A within-trial economic evaluation will be undertaken, with effects expressed as quality-adjusted life years. Discussion: This is a single-centre, phase III, double-blind, randomised placebo-controlled clinical trial to assess whether carrageenan nasal and throat spray reduces the risk of development and severity of COVID-19. If proven effective, the self-administered prophylactic spray would have wider utility for key workers and the general population. Trial registration: NCT04590365; NCT04590365. Registered on 19 October 2020.

Item Type: Article
Date Type: Published Online
Status: Published
Schools: Medicine
Additional Information: License information from Publisher: LICENSE 1: URL:, Type: open-access
Publisher: BioMed Central
ISSN: 1745-6215
Date of First Compliant Deposit: 16 September 2022
Date of Acceptance: 24 August 2022
Last Modified: 11 Nov 2022 09:01

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