Chloroquine prevention of coronavirus disease (COVID-19) in the healthcare setting; a randomised, placebo-controlled prophylaxis study (COPCOV)

Status: Suspended

Type: Interventional

Funder: Wellcome Trust

Sponsor: University of Oxford

CI: Dr Martin Llewelyn

IRAS-Number: 282109

CPMS-ID: 45731

Approval Date: 30 March 2020


There is no proven treatment, chemoprophylaxis or vaccine for COVID-19. This is the most serious pandemic emergency for 100 years – it has already had a devastating effect on the world economy. Healthcare workers are being affected disproportionately in the continuing epidemic. Significant infection rates in this critical group are resulting in a breakdown of health services.

Chloroquine and hydroxychloroquine are safe and well-tolerated medications which can be taken for years without adverse effects. Chloroquine and hydroxychloroquine have significant antiviral activity against SARS-CoV-2 and there is emerging evidence from China and Europe of efficacy in treatment.

We are conducting a multi-centre, multi-country randomised, double blind, placebo controlled assessment of the prophylactic efficacy of chloroquine (Asia) or hydroxychloroquine (Europe) in preventing COVID-19 illness in at-risk healthcare workers and other frontline staff, or other high-risk groups. At least 40,000 participants in Asia and Europe will be randomised 1:1 to receive chloroquine or hydroxychloroquine (whichever is available in the country) or a matched placebo as daily prophylaxis for three months.

Obtaining evidence on the efficacy of interventions in COVID 19 has been identified by world leaders and WHO as being of the highest priority. The study’s primary objective is the prevention of symptomatic virologically proven coronavirus disease (COVID-19). Secondary objectives are to determine if chloroquine or hydroxychloroquine prophylaxis reduces the clinical severity of COVID-19, prevents asymptomatic COVID-19 and symptomatic acute respiratory infections of another aetiology (non-SARS-CoV-2). If chloroquine and hydroxychloroquine are effective the benefit on health would be enormous.