Efficacy and safety of Chinese herbal medicine to prevent and treat COVID-19 household close contacts in Hong Kong: an open-label, randomized controlled trial.

Objectives: To evaluate the efficacy and safety of CHM in the prevention of COVID-19 infection and treatment for COVID-19 related symptoms.

Design: Prospective open-label randomized controlled trial.

Setting: Participants' home in Hong Kong.

Participants: Participants who had household close contact with COVID-19-infected family members.

Interventions: Close contacts were stratified into 4 groups (cohort A, B, C, D) based on symptoms and infection status and were randomized in 4:1 ratio to receive CHM granules (9g/sachet, two times daily) or blank control for 7 days with 2 weeks of follow-up.

Main Outcome Measures: The primary outcome measure was the rate of positive nucleic acid tests. Secondary outcomes were the proportion of developed COVID-19 related symptoms and adverse events during the whole 3-week study period. Subgroup analysis was used to evaluate demographic factors associated with positive infection rates.

Results: A total of 2163 contacts were enrolled and randomly assigned to the CHM group (1720 contacts) and blank control (443 contacts) group. During the 21 days, the rate of PCR-positive cases in cohort A was markedly lower in the CHM group (3.6%) compared to the control group (7.0%) (=0.036). Overall, the rate of infection in the CHM group was significantly lower than that in the control group (10.69% . 6.03%; RR 0.56, 95% CI 0.39-0.82) after 7-day treatment. No serious adverse events were reported during the medication period.

Conclusion: The preliminary findings indicate that CHM may be effective and safe in preventing COVID-19. Future double-blind, randomized controlled trials and long-term follow-up are needed to fully evaluate the efficacy of CHM in a larger contact population.

Clinical Trial Registration: ClinicalTrials.gov, identifier NCT05269511.