Severe Outcomes in COVID-19 More Likely With Influenza Coinfection

Patients coinfected with influenza and COVID-19 are at higher risk for severe outcomes, though the prevalence of this coinfection is low. These study results were published in the International Journal of Infectious Diseases. 

Investigators conducted a systematic review and meta-analysis to evaluate the prevalence and risk factors of influenza and COVID-19 coinfection and compare the risk for severe outcomes between coinfected and monoinfected (COVID-19) patients. Data for the analysis were sourced between January 2020 and May 2023. Severe outcomes included intensive care unit (ICU) admission, mechanical ventilation, and mortality.

The review included 95 studies, representing a total of 62,107 patients with COVID-19 infection. Overall, 2519 patients tested positive for influenza coinfection within 48 hours of COVID-19 diagnosis.

In a random effects model analysis, the estimated pooled prevalence of coinfection was 2.45% (95% CI, 1.67-3.58; I²=99%), ranging from 0% to 57.33% across included studies.

Further analysis was performed among studies with data available on influenza subtypes. Stratified by subtype, the prevalence of coinfection was 2.19% (95% CI, 1.45-3.30; I²=97) in patients with influenza A (66.61%) and 0.88% (95% CI, 0.61.126; I²=82%) in patients with influenza B (9.05%). Of patients with influenza A, coinfection prevalence was similar between those with H3N2 (0.97%; 95% CI, 0.56-1.64; I²=90%) and those with H1N1 (1.17%; 95% CI, 0.65-2.09; I²=89%).

Coinfection prevalence did not significantly differ among patients grouped by age (<18, 18-59, and ≥60 years) or sex.

In subgroup analyses, the prevalence of coinfection was highest in patients who died (36.67%; 95% CI, 28.22-47.65), followed by those who required ICU admission (8.72%; 95% CI, 3.41-22.33) and outpatients (6.26%; 95% CI, 4.63-8.46).

The risk for ICU admission (odds ratio [OR], 1.34; 95% CI, 0.83-2.17; P =.237), mechanical ventilation (OR, 1.98; 95% CI, 1.07-3.66; P =.030), and mortality (OR, 1.39; 95% CI, 0.87-2.21; P =.172) was increased in coinfected vs monoinfected patients. In addition, coinfection with influenza A vs B was more significantly associated ICU admission (OR, 2.20; 95% CI, 1.68-2.87; P <.001), mechanical ventilation (OR, 2.73; 95% CI, 1.46-5.10; P =.002), and mortality (OR, 2.92; 95% CI, 1.16-7.30; P =.022). 

Limitations of this analysis include potentially biased estimates of coinfection prevalence due to inconsistencies in the method of influenza detection, as well as the inability to determine whether different phases of the COVID-19 pandemic affected patient prognosis. 

According to the investigators, “[I]ndividualized treatment protocols should be developed to intervene and manage co-infected patients to reduce the risk of serious consequences.”

This article originally appeared on Infectious Disease Advisor