Efficacy of a Nasal Spray Containing Iota-Carrageenan in the Postexposure Prophylaxis of COVID-19 in Hospital Personnel Dedicated to Patients Care with COVID-19 Disease

Int J Gen Med. 2021 Oct 1:14:6277-6286. doi: 10.2147/IJGM.S328486. eCollection 2021.


Background: Iota-Carrageenan (I-C) is a sulfate polysaccharide synthesized by red algae, with demonstrated antiviral activity and clinical efficacy as nasal spray in the treatment of common cold. In vitro, I-C inhibits SARS-CoV-2 infection in cell culture.

Research question: Can a nasal spray with Iota-Carrageenan be useful in the prophylaxis of COVID-19 in health care workers managing patients with COVID-19 disease?

Study design and methods: This is a pilot pragmatic multicenter, randomized, double-blind, placebo-controlled study assessing the use of a nasal spray containing I-C in the prophylaxis of COVID-19 in hospital personnel dedicated to care of COVID-19 patients. Clinically healthy physicians, nurses, kinesiologists and other health care providers managing patients hospitalized for COVID-19 were assigned in a 1:1 ratio to receive four daily doses of I-C spray or placebo for 21 days. The primary end point was clinical COVID-19, as confirmed by reverse transcriptase polymerase chain reaction testing, over a period of 21 days. The trial is registered at ClinicalTrials.gov (NCT04521322).

Results: A total of 394 individuals were randomly assigned to receive I-C or placebo. Both treatment groups had similar baseline characteristics. The incidence of COVID-19 differs significantly between subjects receiving the nasal spray with I-C (2 of 196 [1.0%]) and those receiving placebo (10 of 198 [5.0%]). Relative risk reduction: 79.8% (95% CI 5.3 to 95.4; p=0.03). Absolute risk reduction: 4% (95% CI 0.6 to 7.4).

Interpretation: In this pilot study a nasal spray with I-C showed significant efficacy in preventing COVID-19 in health care workers managing patients with COVID-19 disease.

Clinical trials registration: NCT04521322.

Keywords: COVID-19; hospital workers; nasal; prophylaxis; spray.

Publication types

  • Case Reports
  • Clinical Trial

Associated data

  • ClinicalTrials.gov/NCT04521322

Grants and funding

The study did not receive any support for hospitals, staff or patients involved. Publication and administrative costs were supported by: Programa de articulación y fortalecimiento federal de las capacidades en ciencia y tecnología COVID-19, Proyecto CABA 20. Ministerio de Ciencia, Tecnología e Innovación, Argentina. Laboratorio Pablo Cassará provided the drug and placebo samples, free of charge.