Prophylaxis for renal patients at risk of COVID-19 infection: results from the intranasal niclosamide randomised, double blinded, placebo controlled arm of the PROTECT-V platform trial

Purpose: Despite vaccination, many patients remain vulnerable to COVID-19 infection and poorer outcomes, because of underlying health conditions resulting in sub-optimal vaccine responses. This study aims to demonstrate whether intranasal niclosamide confers additional protection against COVID-19 infection above standard preventative measures including vaccination. Methods: PROTECT-V (PROphylaxis for paTiEnts at risk of COVID-19 infecTion) is a platform trial testing multiple pre-exposure COVID-19 prophylactic agents in vulnerable patients. This paper reports results from the randomised, double blind, placebo controlled intranasal niclosamide arm. 1651 adult patients on dialysis, with a kidney transplant or renal autoimmune conditions on immunosuppression were randomised from 48 sites (37 UK; 11 Indian). Intranasal niclosamide or matched placebo was administered twice daily, for up to nine months. Primary outcome was time to symptomatic COVID-19 infection. Results: 1651 patients were randomised (826 niclosamide;825 placebo) between February 2021 to November 2022. 655(39.7%) were dialysis patients, 622(37.7%) kidney transplant recipients and 374(22.7%) had renal autoimmune disease. 97.5% patients in the UK and 66.4% patients in India with comparable proportions in both treatment groups had received COVID-19 vaccinations. Despite no adverse safety signal, there was a high withdrawal rate (40% niclosamide;23.8% placebo) due to local upper airway irritation leading to a significantly shorter treatment duration in the niclosamide group). Symptomatic COVID-19 infection during study treatment was observed in 103 patients in the niclosamide group and 133 in the placebo group (estimated hazard ratio 1.02(95%CI 0.79–1.32)). Conclusion: Intranasal niclosamide did not reduce risk of symptomatic COVID-19 infection in this cohort compared to placebo. Trial Registration: This study is registered with ClinicalTrials.gov: NCT04870333 (submitted 01/03/2021; posted 03/05/2021), EudraCT: 2020–004144-28 and the Clinical Trials Registry of India (CTRI):#CTRI/2022/03/040802.