Iota-carrageenan inhibits the cell entry of SARS-CoV-2

In the absence of a vaccine and other effective prophylactic or therapeutic counter measures the severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2) remains a significant public health threat.

The antiviral activity of iota-carrageenan has been demonstrated in vitro against a variety of respiratory viruses (Rhinoviruses, Coronaviruses OC43, 229E, Influenza, Parainfluenza, Human Metapneumovirus and Respiratory Syncytial Virus) [2-4].

The therapeutic effectiveness of iota-carrageenan has been proven in four clinical trials with more than 600 patients suffering from early symptoms of the common cold [10-14]. A particular advantage of iota-carrageenan is the broad activity of the polymer against different virus strains, such as Rhinovirus and already known Coronaviruses.

Data from cell-culture study confirm that iota-carrageenan works in a dose-dependent manner to strongly reduce the infection of cells from the novel beta coronavirus SARS-CoV-2.

Typically, people can become ill with COVID-19 after the SARS-CoV-2 virus has entered the body through the nose or throat. Iota-carrageenan coats the mucosal tissues of the respiratory tract susceptible to attack from SARS-CoV-2, forming a physical barrier that helps to protect against viral infection and viral spread. This in turn may suppress the viral load and the body’s own natural defences may fight the virus more efficiently.

Pre-clinical data show that iota-carrageenan has the potential to reduce the risk of an infection with SARS-CoV-2 and may also treat COVID-19.

Read the pre-print review of the study


Carragelose® (iota-carrageenan) reduces the viral load > 90%

Agovirax publications chart

For the determination of respiratory virus load and virus identification in nasal lavage, real time PCR analysis was performed on Visit 1 and Visit 2.The resulting values of virus positive samples from the first visit were set 100%. The relative quantity of virus positive samples at the second visit was calculated in percent of the value of the first visit. Viral load in the placebo group increased almost 6-fold (579%), while it dramatically decreased by 92% in the Iota-Carrageenan group (p < 0.009). This result indicates that the treatment of patients with Iota-Carrageenan nasal spray leads to a highly statistically significant reduction of viral load in the nasal cavity, while placebo treatment has no influence on viral replication at all.

Carragelose® (iota-carrageenan) shortens the duration of the disease by ~2 days

Agovirax publications chart

The intensity of common cold symptoms was similar for iota-carrageenan (6.42 ± 0.18) and placebo (6.59 ± 0.16) treated patients at visit #1. Duration of common cold symptoms was significantly reduced in iota-carrageenan treated patients compared to placebo treated ones with the average duration of disease diminishment by 2 days (in children group 7.6 vs 9.4 days, in adults group 11.6 vs 13.7 days).

Carragelose® (iota-carrageenan) reduces the common cold symptoms severity almost 3 times

Agovirax publications chart

Severity of symptoms was assessed thru Total Symptom Score, calculated as sum of 8 individual symptoms (headache, muscle ache, chilliness, sore throat, blocked nose, runny nose, coughing and sneezing). Significant reduction of symptoms severity in iota-carrageenan group was visible as of day 4.

Carragelose® (iota-carrageenan) lowers frequency of relapses by 2-fold

Agovirax publications chart

During the 21 days of observation, relapses were observed significantly more frequently in placebo groups than in iota-carrageenan treated patients (p = 0.01). As some patients had more than one relapse during observation period, the average number of relapses per patient was calculated. The average number of relapses per patient was significantly higher in placebo group, namely 0.38 compared to 0.15 in iota-carrageenan group during observation period (p = 0.01).

Recommendations on viruses and the common cold:

  • Center for Disease Control and Prevention (link: )
  • BMJ Best Practice review for Common Cold (link: )
    The text has been adapted from BMJ Best Practice Common Cold review and BMJ Learning does not endorse Agovirax, nor are they making Agovirax usage recommendations.
  • National Health Institute – U.S. National Library of Medicine Common cold (Link: )

Studies with Agovirax active substances:

  1. SARS-CoV-2 in-vitro neutralization assay reveals inhibition of virus entry by iota-carrageenan. Martina Morokutti-Kurz et al, 2020. BioRxiv preprint doi:
  2. Bansal et al. Iota-carrageenan and Xylitol inhibit SARS-CoV-2 in cell culture. Posted August 21, 2020. doi: bioRxiv preprint.
  3. Carvallo et al. Study of the Efficacy and Safety of Topical Ivermectine + Iota-carrageenan in the Prophylaxis Against COVID-19 in Health Personnel.Grassauer et al. Iota-Carrageenan is a potent inhibitor of rhinovirus infection. Virology Journal 2008, 5:107.
  4. Leibbrandt A et al. Iota-Carrageenan Is a Potent Inhibitor of Influenza A Virus Infection. PLoS ONE 5(12): e14320. doi:10.1371/journal.pone.00143202.
  5. Eccles R. et al. Efficacy and safety of an antiviral Iota-Carrageenan nasal spray: a randomized, double-blind, placebo-controlled exploratory study in volunteers with early symptoms of the common cold. Respiratory Research 2010, 11:108.
  6. Fazekas T. et al. Lessons learned from a double-blind randomised placebo-controlled study with a iota-carrageenan nasal spray as medical device in children with acute symptoms of common cold BMC Complementary and Alternative Medicine 2012, 12:147.
  7. Ludwig et al.: Efficacy of a Carrageenan nasal spray in patients with common cold: a randomized controlled trial. Respiratory Research 2013 14:124.
  8. Koenighofer et al.: Carrageenan nasal spray in virus confirmed common cold: individual patient data analysis of two randomized controlled trials. Multidisciplinary Respiratory Medicine 2014 9:57.
  9. Eccles R. et al. Ecacy and safety of iota-carrageenan nasal spray versus placebo in early treatment of the common cold in adults: the ICICC trial.Respiratory Research (2015) 16:121. DOI 10.1186/s12931-015-0281-8.
  10. Eccles R. Iota-Carrageenan as an Antiviral Treatment for the Common Cold. The Open Virology Journal, 2020, Volume 14.