Echinacea Purpurea For the Long-Term Prevention of Viral Respiratory Tract Infections During Covid-19 Pandemic: A Randomized, Open, Controlled, Exploratory Clinical Study

Abstract

SARS-CoV-2 vaccination is effective in preventing severe Covid-19, but efficacy in reducing viral load and transmission wanes over time. In addition, the emergence of novel SARS-CoV-2 variants increases the threat of uncontrolled dissemination and additional antiviral therapies are urgently needed for effective containment. In previous in vitro studies Echinacea purpurea demonstrated strong antiviral activity against enveloped viruses, including SARS-CoV-2. In this study, we examined the potential of Echinacea purpurea in preventing and treating respiratory tract infections (RTIs) and in particular, SARS-CoV-2 infections. 120 healthy volunteers (m,f, 18—75 years) were randomly assigned to Echinacea prevention or control group without any intervention. After a run-in week, participants went through 3 prevention cycles of 2, 2 and 1 month with daily 2,400 mg Echinacea purpurea extract (Echinaforce®, EF). The prevention cycles were interrupted by breaks of 1 week. Acute respiratory symptoms were treated with 4,000 mg EF for up to 10 days, and their severity assessed via a diary. Naso/oropharyngeal swabs and venous blood samples were routinely collected every month and during acute illnesses for detection and identification of respiratory viruses, including SARS-CoV-2 via RT-qPCR and serology. Summarized over all phases of prevention, 21 and 29 samples tested positive for any virus in the EF and control group, of which 5 and 14 samples tested SARS-CoV-2 positive (RR = 0.37, Chi-square test, p = 0.03). Overall, 10 and 14 symptomatic episodes occurred, of which 5 and 8 were Covid-19 (RR = 0.70, Chi-square test, p > 0.05). EF treatment when applied during acute episodes significantly reduced the overall virus load by at least 2.12 log10 or approx. 99% (t-test, p < 0.05), the time to virus clearance by 8.0 days for all viruses (Wilcoxon test, p = 0.02) and by 4.8 days for SARS-CoV-2 (p > 0.05) in comparison to control. Finally, EF treatment significantly reduced fever days (1 day vs 11 days, Chi-square test, p = 0.003) but not the overall symptom severity. There were fewer Covid-19 related hospitalizations in the EF treatment group (N = 0 vs N = 2). EF exhibited antiviral effects and reduced the risk of viral RTIs, including SARS-CoV-2. By substantially reducing virus loads in infected subjects, EF offers a supportive addition to existing mandated treatments like vaccinations. Future confirmatory studies are warranted.

Comparison of Preprint Postings of Randomized Clinical Trials on COVID-19 and Corresponding Published Journal Articles

“…As of October 1, 2022, 119 preprints (78.3%) had been published in a scientific, peer-reviewed journal (Figure 2 and eTable 3 in Supplement 1). Two preprints were published in a single journal publication . The median time to publication was 186 days (range, 17-407 days).…”

Novel Echinacea formulations for the treatment of acute respiratory tract infections in adults—A randomized blinded controlled trial

“…Interestingly, the strongest antiviral effects were found when epithelial cells were in direct contact with EF indicating immediate treatment or prophylactic benefits rather than with post-exposure of cells ( 8 , 12 ). In randomized, double-blind placebo-controlled trials, the prophylactic use of EF significantly reduced the incidence of laboratory-confirmed viral RTIs and was non-inferior to the placebo in terms of safety ( 13 – 15 ). Similar results were found for Echinaforce Hot Drink ® which was non-inferior to oseltamivir in the treatment of ILI.…”

“…Randomized, controlled clinical studies (RCTs) have demonstrated efficacy for a 65% hydroethanolic extract from Echinacea purpurea herb and roots (Echinaforce ® [EF]) in the prevention and the treatment of RTIs including secondary complications ( 13 – 17 ). Five months of EF prevention during the COVID-19 pandemic (2020–2021) reduced enveloped virus infections by 43.2%, coronavirus infections by 48.3%, and SARS-CoV-2 by 63.1% ( p < 0.05) ( 15 ). Moreover, Nicolussi et al found significantly reduced enveloped virus infections in adults and children and >98% decreased viral loads with increased EF dosages used for the acute treatment ( 18 ).…”

Natural Products for the Prevention and Treatment of Common Cold and Viral Respiratory Infections

“…In vitro experiments with human macrophages found that fresh-pressed juice and dried juice from the aerial parts of E. purpurea stimulated the production of cytokines including IL-1, IL-10, and TNF-α [ 54 ]. In addition, evidence pointed out the effective activity of E. purpurea towards Coronavirus disease 2019 (COVID-19) in an organotypic cell culture model [ 55 , 56 , 57 ].…”