Low Prevalence of COVID-19 and Flu Coinfection Found in Real-world Cohort Study

The prevalence of coinfection with COVID-19 and influenza was found to be low in a real-world cohort study being presented at Infectious Disease Week (IDWeek) 2021 Annual Meeting, held virtually from September 29 to October 3, 2021.

Researchers used data from US electronic health records (EHRs) to estimate coinfection prevalence of COVID-19 and influenza and compare demographics and clinical outcomes of coinfected patients to those infected with COVID-19 only.

Patients in the Optum De-identified COVID-19 EHR database diagnosed with COVID-19 between February 2020 and January 2021 were eligible. Influenza coinfection was defined for the purpose of the study as an influenza diagnosis within 10 days of COVID-19 diagnosis. Prevalence of coinfection was reported for all COVID-19 patients and a subset of hospitalized COVID-19 patients.

Among the 549 532 COVID-19 patients included in the study, 1794 (0.3%) were coinfected with influenza, according to the study abstract. Among the 80 192 hospitalized COVID-19 patients, 242 (0.3%) were coinfected with influenza.

In sensitivity analyses restricting to lab-confirmed influenza, coinfection prevalence was 0.1% overall and 0.2% in the hospitalized subset. No meaningful differences were observed in baseline demographics between COVID-19 singly-infected patients and coinfected patients.

Among the hospitalized subset, univariate analysis showed higher likelihood of invasive ventilation (12.8% vs 9.8%; p=0.14), respiratory failure (56.2% vs 46.6%; p<.01), and intensive care unit stay (27.3% vs 23.1%; p=0.13), but no meaningful difference in death (13.3% vs 13.0%; p=0.97), for coinfected patients as compared to COVID-19-only patients, according to the abstract.

“Co-infected patients had similar baseline characteristics but higher likelihood of hospitalization severity as compared to singly-infected COVID-19 patients. Limitations include low prevalence of circulating influenza and potential missing data bias,” concluded researchers.

The study abstract will be presented during the IDWeek 2021 poster session titled COVID-19 Complications, Co-infections, and Clinical Outcomes.


Source: Chawla D, Chen X, Kuhlbusch K, Zalocusky K, Rizzo S. Prevalence of influenza co-infection in a real-world cohort of COVID-19 patients in the U.S. 281.