Intended for healthcare professionals

Rapid response to:

Editor's Choice

Covid-19: A wake-up call

BMJ 2020; 369 doi: (Published 21 May 2020) Cite this as: BMJ 2020;369:m2021

Rapid Response:

Re: Covid-19: A wake-up call

Dear Editor

Proposed Trials of Ivermectin for post-exposure prophylaxis of COVID 19

In contemplating the next phases of COVID management, we clearly need more options for disease prophylaxis, because ongoing COVID clusters seem guaranteed until/if effective vaccines can be developed and widely applied. Australia has done well in containing the first onslaught of the virus, with about 7,000 recognised cases and 102 deaths. However, after flattening the curve, we have COVID clusters in specific locations like nursing homes, abattoirs and fast-food chains; we wait for others in prisons, sports camps, boarding schools, institutions and the like, anticipate more with the relaxation of stay-at-home and social distancing policies, and with the resumption of public transport, air travel, cruises and tourism, and dread their appearance in Indigenous communities and health services, and disadvantaged settings generally.

There must be more discussions and trials of options for targeted and time-limited post-exposure prophylaxis (1) for contacts of people with diagnosed COVID infections, with the objective of reducing rate and severity of subsequent infections in those contacts and limiting further community spread. These interventions would be separate from, or additional to, other strategies like strengthened nonspecific population immunity (2), vaccines, or protection for people with sustained exposure, like the pending trial of hydroxychloroquine in health workers (3).

We argue for an urgent trial of Ivermectin for post-exposure prophylaxis in close contacts of known COVID cases. Ivermectin reportedly kills the COVID-19 virus in vitro, although, as yet, at very high concentrations (4). It is cheap, easily administered by mouth, well-tolerated, with a wide margin of safety; furthermore it already the subject of a $20 USD million repurposing venture for COVID treatment (5). However, we should not wait for results of controlled trials in clinical COVID cases; even negative results in that setting will not prelude potential benefit in prophylaxis, where the viral load in recently exposed people is less (6), immunity still intact and organ damage and superinfections not yet established. The stakes are so high, and the costs and dangers so minimal, that we are obliged to try it.

Wendy Elizabeth Hoy and Vishal Diwan

CKD.QLD and NHMRC CKD.CRE, Faculty of Medicine, The University of Queensland, Brisbane, Australia

1. Davis JS, Ferreira D, Denholm JT, Tong SYC. Clinical trials for the prevention and treatment of coronavirus disease 2019 (COVID-19): The current state of play. Med J Aust. Published online: 27 April 2020.
2. Curtis N, Sparrow A, Ghebreyesus TA, Netea M, Considering BCG vaccination to reduce the impact of COVID-19. 2020; 16;395 (10236):1545-1546. doi: 10.1016/S0140-6736(20)31025-4.
3. Global clinical trial of 40,000+ healthcare workers begins to test in UK if chloroquine and hydroxychloroquine can prevent COVID-19; Source: Centre for Tropical Medicine and Global Health:
4. Caly J, Druce JD, Catton MG, Jans DA, Wagstaffb KM. The FDA-approved drug ivermectin inhibits the replication of SARS-CoV-2 in vitro. Antiviral Therapy. Volume 178, June 2020, 104787.
5. Gates Foundation funded French Research Group commences Clinical Trial targeting COVID-19., DOI April 26, 2020.
6. Coronavirus: does the amount of virus you are exposed to determine how sick you’ll get? Apr 7, 2020:

Competing interests: No competing interests

25 May 2020
Wendy E Hoy
Professor/Physician /Nephrologist/Population health researcher
Vishal Diwan; Research Coordinator/Manager: Centre for Chronic Disease, Royal Brisbane and Women's Hospiital, Brisbane, Queensland, 4029
The University of Queensland
Centre for Chronic Disease, Royal Brisbane and Women's Hospiital, Brisbane, Queensland, 4029