Does Doxycycline Therapy in COVID-19 Pneumonia Improve Mortality?

microscopic pneumonia in lungs
microscopic pneumonia in lungs
What effect does doxycycline have on patients with COVID-19 pneumonia?

The following article is a part of conference coverage from the American College of Allergy, Asthma & Immunology 2021 Annual Scientific Meeting, being held virtually from November 4 to 8, 2021. The team at Pulmonology Advisor will be reporting on the latest news and research conducted by leading experts in the field. Check back for more from the ACAAI 2021 Annual Scientific Meeting.


The use of doxycycline therapy in patients with COVID-19 pneumonia is not associated with improved mortality rates, according to research findings being presented at the American College of Allergy, Asthma & Immunology (ACAAI) 2021 Annual Scientific Meeting, November 4 to 8, in New Orleans, LA.

The researchers examined outcomes linked to doxycycline treatment in hospitalized patients with COVID-19 pneumonia through a retrospective, observational chart review of patients admitted to University Hospital in Brooklyn, NY, between March 2020 and June 2020, for COVID-19–related symptoms.

A total of 478 charts of patients who were polymerase chain reaction–positive for SARS-CoV-2 infection were reviewed. Overall, 110 patients with COVID-19 were treated with doxycycline. Researchers extracted the following data points from all patient charts: (1) the Charlson Comorbidity Index rate (a 10-year survival predictor that is based on a patient’s age and comorbidities); (2) all medications administered to the patient; (3) National Early Warning Score (NEWS)-2 (a measurement of the degree of illness in a particular patient, which can then be beneficial in prompting the use of any critical care intervention); and (4) length of hospital stay.

The investigators developed a frequency table that included any doxycycline use according to a patient’s mortality status. They used forward-selection logistic regression to construct a model that was capable of predicting mortality with the use of potential risk factors. Investigators also evaluated any interactions among the predictors, as well as polynomial terms in scored predictors.

The crude prevalence of mortality reported was 50.9% in patients treated with doxycycline vs 37.8% in other patients (P =.015). The forward regression model showed that significant, independent predictors of mortality in these patients included older age, male gender, higher NEWS-2 score, and month of hospital admission. After controlling for these risk factors, the adjusted odds ratio (aOR) of death was no longer significant (aOR, 0.97; 95% CI, 0.90-1.04; P =.373). A further logistic regression risk model that included every risk factor that was assessed reported an aOR of 0.99 (95% CI, 0.91-1.07; P =.722).

The researchers concluded that although tetracyclines such as doxycycline are known to exhibit anti-inflammatory effects, along with immune-modulating, cardioprotective, and antiviral activities, the outcomes associated with doxycycline treatment in the current analysis did not demonstrate improvements in mortality among patients with COVID-19 pneumonia.

Disclosure: None of the study authors have declared affiliations with biotech, pharmaceutical, and/or device companies.


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Majzoub M, Joks R. Treating COVID-19 pneumonia with doxycycline does not improve mortality. Presented at: American College of Allergy, Asthma & Immunology (ACAAI) 2021 Annual Scientific Meeting; November 4-8, 2021; New Orleans, LA. Abstract P154.