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To consider or not antimalarials as a prophylactic intervention in the SARS-CoV-2 (COVID-19) pandemic
  1. Konstantinos Parperis1,2
  1. 1 Internal Medicine, Division of Rheumatology, University of Cyprus Medical School, Nicosia, Cyprus
  2. 2 Medicine, Division of Rheumatology, University of Arizona College of Medicine, Phoenix, Arizona, USA
  1. Correspondence to Dr Konstantinos Parperis, Internal Medicine, Division of Rheumatology, University of Cyprus Medical School, Nicosia 1678, Cyprus; kparpe02{at}

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I read with great interest the letter by Spinelli et al published in the Annals of the Rheumatic Diseases.1 The authors describe the existing scientific evidence concerning the potential antiviral activity of chloroquine and hydroxychloroquine (HCQ) against SARS-CoV-2 (COVID-19) infection in vitro, and the available clinical studies.

In my opinion, caution must be exercised before drawing any conclusions about the efficacy of antimalarials as prophylactic or therapeutic options for COVID-19 infection, given the concerns raised by healthcare providers related to inadequate supply for patients with chronic conditions such as systemic lupus erythematosus and rheumatoid arthritis.2

So far, there is no substantial evidence to support the beneficial role of antimalarials. In particular, the authors cited an article by Gao et al,3 which reported that the administration of chloroquine phosphate in 100 Chinese patients with COVID-19 infection was superior, compared with the control group, on the following endpoints: exacerbation of pneumonia, improvement of radiographic findings, virus-negative conversion and disease duration. Surprisingly, the authors did not provide any information about demographics, if the patients were hospitalised or not, the clinical characteristics of both groups, baseline treatment regimens, and the primary or secondary endpoints.

In contrast to the above report, a small pilot study from China showed no difference between HCQ-treated patients compared with a control group in terms of negative conversion rate of pharyngeal swabs, duration of fever and radiographic progression on CT chest images.4

Anecdotal reports from registries of patients with COVID-19 infection and autoimmune rheumatic diseases demonstrated that approximately 25% of infected patients were already taking HCQ, indicating HCQ might not have any protective effect.

Lastly, we agree with the authors of the urgent need for large clinical trials to assess the efficacy and safety of antimalarial treatments in patients with COVID-19 infection.



  • Contributors KP: conception or design of the work, acquisition, analysis or interpretation of data for the work, drafting the work or revising it critically for important intellectual content, final approval of the version to be published, and agree to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.

  • Patient consent for publication Not required.

  • Provenance and peer review Not commissioned; internally peer reviewed.

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