The US’ National Institutes of Health (NIH) has started a Phase IIb clinical trial to assess malaria drug hydroxychloroquine plus the antibiotic azithromycin to treat Covid-19.

NIH’s National Institute of Allergy and Infectious Diseases (NIAID) is funding the study, which is being performed by the NIAID-funded AIDS Clinical Trials Group (ACTG).

Teva Pharmaceuticals will supply drugs for the study, which will involve around 2,000 adult patients at participating ACTG sites across the US. Several participants are expected to be aged 60 years and above or have a comorbidity such as diabetes.

Patients will be given short-term treatment with hydroxychloroquine plus azithromycin or placebos. The first participant has been recruited in San Diego, California.

NIAID director Anthony Fauci said: “Repurposing existing drugs is an attractive option because these medications have undergone extensive testing, allowing them to move quickly into clinical trials and accelerating their potential approval for Covid-19 treatment.

“Although there is anecdotal evidence that hydroxychloroquine and azithromycin may benefit people with Covid-19, we need solid data from a large randomised, controlled clinical trial to determine whether this experimental treatment is safe and can improve clinical outcomes.”

Subjects will take medication at home and record their symptoms, adherence to treatment, and major events such as hospitalisations in a diary for 20 days. Trial staff will follow up during this period via telephone.

The primary objective of the trial is the ability of hydroxychloroquine plus azithromycin to prevent hospitalisation and death from Covid-19. The safety and tolerability of the treatment will also be assessed.

Initial data from the trial is expected to be made available later this year.

Earlier this month, the Translational Genomics Research Institute (TGen), HonorHealth Research Institute, and HonorHealth started enrolling patients for a trial of atovaquone plus azithromycin to treat moderate-to-severe Covid-19.