Doxycycline treatment of high-risk COVID-19-positive patients with comorbid pulmonary disease

Infection with novel SARS-CoV-2 carries significant morbidity and mortality in patients with pulmonary compromise, such as lung cancer, autoimmune disease, and pneumonia. For early stages of mild to moderate disease, care is entirely supportive. Antiviral drugs such as remdesivir may be of some benefit but are reserved for severe cases given limited availability and potential toxicity. Repurposing of safer, established medications that may have antiviral activity is a possible approach for treatment of earlier-stage disease. Tetracycline and its derivatives (e.g. doxycycline and minocycline) are nontraditional antibiotics with a well-established safety profile, potential efficacy against viral pathogens such as dengue fever and chikungunya, and may regulate pathways important in initial infection, replication, and systemic response to SARS-CoV-2. We present a series of four high-risk, symptomatic, COVID-19(+) patients, with known pulmonary disease, treated with doxycycline with subsequent rapid clinical improvement. No safety issues were noted with use of doxycycline. Doxycycline is an attractive candidate as a repurposed drug in the treatment of COVID-19 infection, with an established safety profile, strong preclinical rationale, and compelling initial clinical experience described here. The reviews of this paper are available via the supplemental material section.