A recent study published in Clinical Infectious Diseases assessed deaths due to fungal infections during the coronavirus disease 2019 (COVID-19) pandemic in the United States (US).
Yeasts, molds, dimorphic fungi, and yeast-like fungi are common fungal pathogens. Clinically, fungal infections result in superficial lesions as well as life-threatening conditions. Severe infections typically affect immunosuppressed individuals like cancer patients, recipients of solid organ or stem cell grafts, users of immunosuppressive medication, etc.
More than a million people have succumbed to COVID-19 in the US to date. Moreover, COVID-19 might elevate the risk for severe fungal infection due to COVID-19-associated immune dysfunction, lung damage, and therapies, impairing the host immune system against pathogenic fungi. Evidence suggests that severe fungal infection in COVID-19 patients could result in poor clinical outcomes.
About the study
The present study analyzed data from the US National Vital Statistics System (NVSS) to examine demographic information, fungal disease burden, and temporal trends. They used provisional mortality data for 2021 and final mortality data for 2018 – 2020 from NVSS. Deaths involving fungal infections were identified and coded according to the International Classification of Diseases, tenth revision (ICD-10) codes. Deaths involving COVID-19 were similarly coded.
The number, percentage, and age-adjusted rates of fungal deaths from January 2018 to December 2021 were analyzed by the fungal pathogen, year, and COVID-19 association (whether COVID-19 was a contributory factor). The monthly number of fungal deaths during the COVID-19 pandemic was examined by investigating whether COVID-19 contributed to mortality; concurrent monthly COVID-19 deaths were also analyzed.
Data on fungal deaths between January 2020 and December 2021 were stratified by the COVID-19 association; the age-adjusted death rates were examined by race/ethnicity, sex, fungal pathogens, and the US census division of residence.
Between 2018 and 2021, 22,700 deaths occurred due to fungal infections/pathogens. The number of fungal deaths per 100,000 people for 2018 and 2019 was similar, with 4746 and 4833 deaths, respectively, and the age-adjusted rate was 1.2 during both years. However, it increased to 5922 in 2020, with a mortality rate of 1.5. Likewise, about 7199 (fungal) deaths were observed in 2021, with a rate of 1.8.
COVID-19-associated deaths during 2020 and 2021 accounted for 21.9% of the 13,121 fungal deaths in that period. COVID-19 represented the most common underlying cause of death (90.5%) among the COVID-19-associated fungal deaths, accounting for 0.3% of COVID-19 deaths during 2020-21. Candida and Aspergillus were the common fungal pathogens constituting 24.4% and 16.4% of the total number of fungal deaths for 2020-21.
Nevertheless, the pathogen was unspecified for more than 35% of all fungal deaths in the same period. Notably, COVID-19-associated fungal deaths were predominantly due to Candida and Aspergillus infections relative to non-COVID-19-associated fungal deaths. On average, 399 fungal deaths were recorded per month during 2018-19, and 423 fungal deaths occurred during the peak of the first COVID-19 wave (April 2020). Nonetheless, it peaked in January 2021 and October 2021 with 690 and 718 fungal deaths coinciding with the COVID-19 mortality peak(s).
Most deaths from fungal infections in 2020-21 were recorded in males (59.7%) and people aged 65 or above. The age-adjusted rates for COVID-19-associated fungal deaths were higher for individuals who were non-Hispanic American Indian or Alaska Native (AI/AN) [1.3], Hispanic (0.7), and Black (0.6) than non-Hispanic White (0.2) and non-Hispanic Asian (0.3) populations.
Consistently, for non-COVID-19-associated deaths from fungal infections, the age-adjusted death rates were higher in AI/AN (3), Hispanic (1.9), and non-Hispanic native Hawaiian (NHPI) [2.4] and Black populations than White (1.1) or Asian (1.2) individuals. The crude fungal death rate was higher for people from non-metropolitan areas than metropolitan residents.
The age-adjusted fungal death rates were higher in the Mountain (2.1) and Pacific (2) US census divisions but lower in the New England (1.3) division. Mountain and West South-Central divisions showed higher rates (0.5) of non-COVID-19-associated deaths, while it was lower in New England division (0.2).
The researchers observed that more people died from fungal infections in 2020-21, an upward trend compared to preceding years. COVID-19-associated fungal deaths drove this increase, highlighting the critical significance of fungal infections in COVID-19 patients. Fungal deaths increased in tandem with COVID-19 peaks in January and October 2021 but not in April 2020.
In conclusion, the study demonstrated that fungal infections pose a substantial burden in the US. These results might help inform efforts to identify, treat, or prevent severe fungal infections in COVID-19 patients, particularly in some ethnic and racial groups and geographic regions.