The Nitazoxanide Plus Atazanavir for COVID-19 Study (NACOVID)

COVID-19 caused by a novel severe acute respiratory syndrome coronavirus (SARS-CoV-2) is an unprecedented global public health challenge which as at July 1, 2020 has spread to over 210 countries with over 10.6 million cases resulting in 514,808 deaths. More than 1500 clinical trials are currently ongoing in an unprecedented global search for potential therapeutics and vaccines. With increasing number of cases reported in low- and middle-income countries and and the possibility of a second wave of infections in countries where the pandemic appears to have slowed, studies to investigate promising therapies are urgently needed, especially those that can significantly reduce time to viral clearance and mortality. Shortening SARS-CoV-2 clearance time will lower treatment cost and reduce the economic impact of the pandemic.

The purpose of this phase 2 trial is to investigate the efficacy and safety of repurposed antiprotozoal and antiretroviral drugs, nitazoxanide and atazanavir/ritonavir, in achievement of SARS-CoV-2 PCR negativity and shorten the time to clinical improvement in patients diagnosed with moderate to severe COVID-19. The selection of candidates for this COVID-19 drug repurposing trial was guided by three pharmacological considerations: (1) demonstration of in-vitro anti-SARS-CoV-2 activity at doses shown or predicted to be tolerated by humans, (2) the feasibility of achieving effective concentration in relevant compartments, and (3) established human safety record.

This is a pilot phase 2, open label randomized controlled trial. A total of 98 patients with confirmed COVID-19 diagnosis (defined as SARS-CoV-2 polymerase chain reaction (PCR) positive nasopharyngeal swab) will be recruited from participating treatment centres. Participants will be randomised to receive either the standard of care (SOC) plus nitazoxanide for 14 days, starting from day 1 or the SOC alone for 14 days.

Participants will be recruited within 2 days of admission into COVID-19 treatment centre. Before enrollment, they will be given adequate information about the trial, opportunity to ask questions, and sufficient time to consider participation. Before any screening procedures, a written consent will be obtained from each eligible subject who agrees to participate in the trial. Participants will then be randomly allocated 1:1 to receive either the SOC alone (control group) or SOC plus study drug (intervention group). Parallel assignment will be used to prevent sample size imbalance between groups and control for important covariates (e.g. age, comorbidities, gender) that may affect trial results. Participants in the intervention group will receive 1000 mg nitazoxanide (two tablets of 500 mg each) with meal two times daily (8 am and 8 pm) and one tablet of 300/100 mg atazanavir/ritonavir with meal once daily (8 pm) in addition SOC. Participants in the control arm will receive the SOC alone. SOC will be as determined by the clinical team at the treatment centres in line with the current National Interim Guidelines for Clinical Management of COVID-19.

The treatment duration for participants in the intervention group will be 14 days. However, follow up will continue until day 28 after study entry at the end of which all participants will exit the study. Evaluations at follow up visits will include daily symptoms monitoring using inFLUenza Patient-Reported Outcome (FLU-PRO) questionnaire, daily vitals, daily clinical improvement assessment, and swab and/or sputum collection for SARS-CoV-2 on days 2, 4, 6, 7, 14, and 28.

Sample size estimation is based on the assumption that an improvement of at least 60-80% in time to SARS-CoV-2 PCR negativity and symptoms resolution can be achieved in the intervention group compared with the control group. Hence, a total sample size of 89 will provide at least 80% power to show or exclude 60% improvement in time to SARS-CoV-2 PCR negativity. This assumes a two-sided and 5% type 1 error rate. Therefore, providing for a 10% loss to follow up rate, a total of 98 patients will be recruited.