Human monkeypox outbreak: Epidemiological data and therapeutic potential of topical cidofovir in a prospective cohort study.

Background: Human monkeypox has become increasingly frequent worldwide since the outbreak was first reported in May 2022.

Objectives: As cidofovir is effective against vaccinia and other Orthopoxvirus diseases, we hypothesize that its topical use could be an effective treatment for monkeypox skin lesions, avoiding the adverse effects of systemic administration.

Methods: We conducted a prospective study to collect data on the clinical and virologic course of patients with monkeypox. All patients were offered symptomatic treatment. They were also offered treatment with topical cidofovir on a compassionate use basis. Twelve patients received treatment with topical cidofovir 1%, while the others received only symptomatic treatment. Prospective visits were scheduled for the collection of clinical and virological data.

Results: Lesions cleared quicker in the cidofovir-treated group (hazard ratio, 4.572; P = .0039). The median time to resolution was 12 (11.5-15) and 18 (16-21) days, respectively. On day 14, polymerase chain reaction-positive skin lesions were detected in 10% of the cidofovir sample, compared with 62.5% of the non-treated group (P = .019). Local adverse effects were frequent (50%), especially in the anogenital region. No systemic adverse effects were reported.

Limitations: The study is not a clinical trial and lacks a placebo-controlled arm.

Discussion: Topical cidofovir is a potentially relevant therapy in patients with skin lesions but mild systemic involvement. Reducing time to resolution could shorten isolation time and improve the cosmetic impact in areas such as the face.