No Influence of Previous Coxiella burnetii Infection on ICU Admission and Mortality in Emergency Department Patients Infected with SARS-CoV-2.

Background: the geographical similarities of the Dutch 2007-2010 Q fever outbreak and the start of the 2020 coronavirus disease 19 (COVID-19) outbreak in the Netherlands raised questions and provided a unique opportunity to study an association between Coxiella burnetii infection and the outcome following SARS-CoV-2 infection.
Methods: We performed a retrospective cohort study in two Dutch hospitals. We assessed evidence of previous C. burnetii infection in COVID-19 patients diagnosed at the ED during the first COVID-19 wave and compared a combined outcome of in-hospital mortality and intensive care unit (ICU) admission using adjusted odds ratios (OR).
Results: In total, 629 patients were included with a mean age of 68.0 years. Evidence of previous C. burnetii infection was found in 117 patients (18.6%). The combined primary outcome occurred in 40.2% and 40.4% of patients with and without evidence of previous C. burnetii infection respectively (adjusted OR of 0.926 (95% CI 0.605-1.416)). The adjusted OR of the secondary outcomes in-hospital mortality, ICU-admission and regular ward admission did not show an association either.
Conclusion: no influence of previous C. burnetii infection on the risk of ICU admission and/or mortality for patients with COVID-19 presenting at the ED was observed.