SARS-CoV-2 Associated Immune Dysregulation and COVID-Associated Pulmonary Aspergilliosis (CAPA): A Cautionary Tale

COVID-19-associated pulmonary aspergillosis in patients with severe SARS-CoV-2 infection: A single-center observational study from Greece

INTRODUCTION

COVID-19-associated pulmonary aspergillosis (CAPA) is a serious complication affecting patients with severe SARS-CoV-2 infection, and is associated with increased mortality.

OBJECTIVE

The objective of this study was to investigate potential risk factors, and to estimate the incidence and mortality in patients diagnosed with CAPA.

METHODS

A single-center retrospective observational study was conducted on patients admitted to the intensive care unit (ICU) with severe COVID-19 from October 2020 to May 2022. Patients with deterioration of their clinical status were evaluated with serum galactomannan (GM) for probable CAPA. Baseline demographic patient characteristics, vaccination status, and time period during which each patient was infected with SARS-CoV-2 were obtained, and risk stratification according to underlying comorbidities was performed in an effort to assess various risk factors for CAPA. The incidence of CAPA in the entire cohort was measured, and mortality rates in the CAPA and non-CAPA groups were calculated and compared.

RESULTS

Of 488 patients admitted to the ICU, 95 (19.4%) had deterioration of their clinical status, which prompted testing with serum GM. Positive serum testing was observed in 39/95 patients, with an overall CAPA incidence in the entire study cohort reaching 7.9% (39/488). The mortality rate was 75% (42/56) in the non-CAPA group that was tested for serum GM, and 87.2% (34/39) in the CAPA group (P = 0.041). Multivariable Cox regression hazard models were tested for 28- and 90-day survival from ICU admission. An invasive pulmonary aspergillosis (IPA) risk-stratified cox regression model corrected for the SARS-CoV-2 variant of the patient identified the diagnosis of probable CAPA and elevated procalcitonin (PCT) levels measured at least 10 days after ICU admission, as significantly associated with death in the IPA-risk subgroup only, with hazard ratio (HR): 3.687 (95% confidence interval [CI], 1.030-13.199, P = 0.045) for the diagnosis of probable CAPA, and HR: 1.022 (95% CI, 1.003-1.042, P = 0.026) for every 1 ng/mL rise in PCT.

CONCLUSIONS

Patients in the IPA-risk subgroup that were diagnosed with CAPA had a lower 90-day survival when compared to patients in the same group without a CAPA diagnosis.

Defective antifungal immunity in patients with COVID-19

The COVID-19 pandemic has placed a huge strain on global healthcare and been a significant cause of increased morbidity and mortality, particularly in at-risk populations. This disease attacks the respiratory systems and causes significant immune dysregulation in affected patients creating a perfect opportunity for the development of invasive fungal disease (IFD). COVID-19 infection can instill a significant, poorly regulated pro-inflammatory response. Clinically induced immunosuppression or pro-inflammatory damage to mucosa facilitate the development of IFD and Aspergillus, Mucorales, and Candida infections have been regularly reported throughout the COVID-19 pandemic. Corticosteroids and immune modulators are used in the treatment of COVID-19. Corticosteroid use is also a risk factor for IFD, but not the only reason for IFD in COVID -19 patients. Specific dysregulation of the immune system through functional exhaustion of Natural killer (NK) cells and T cells has been observed in COVID-19 through the expression of the exhaustion markers NK-G2A and PD-1. Reduced fungicidal activity of neutrophils from COVID-19 patients indicates that immune dysfunction/imbalance are important risk factors for IFD. The COVID-19 pandemic has significantly increased the at-risk population for IFD. Even if the incidence of IFD is relatively low, the size of this new at-risk population will result in a substantial increase in the overall, annual number of IFD cases. It is important to understand how and why certain patients with COVID-19 developed increased susceptibility to IFD, as this will improve our understanding of risk of IFD in the face of future pandemics but also in a clinical era of increased clinical immuno-suppression/modulation.

A Regional Observational Study on COVID-19-Associated Pulmonary Aspergillosis (CAPA) within Intensive Care Unit: Trying to Break the Mold

The reported incidence of COVID-19-associated pulmonary aspergillosis (CAPA) ranges between 2.4% and 35% in intensive care unit (ICU) patients, and awareness in the medical community is rising. We performed a regional retrospective observational study including patients diagnosed with CAPA defined according to the Modified AspICU Dutch/Belgian Mycosis Study Group and CAPA-EECMM, from five different ICUs, admitted between March, 2020 and September, 2021. Forty-five patients were included. The median age was 64 (IQR 60-72), mostly (73%) males. At ICU admission, the median Charlson comorbidity index was 3 (2-5), and the simplified acute physiology score (SAPS)-II score was 42 (31-56). The main underlying diseases were hypertension (46%), diabetes (36%) and pulmonary diseases (15%). CAPA was diagnosed within a median of 17 days (IQR 10-21.75) after symptoms onset and 9 days (IQR 3-11) after ICU admission. The overall 28-day mortality rate was 58%, and at univariate analysis, it was significantly associated with older age (p = 0.009) and SAPS-II score at admission (p = 0.032). The use of immunomodulatory agents, p = 0.061; broad-spectrum antibiotics, p = 0.091; positive culture for Aspergillus on BAL, p = 0.065; and hypertension, p = 0.083, were near reaching statistical significance. None of them were confirmed in multivariate analysis. In critically ill COVID-19 patients, CAPA acquired clinical relevance in terms of incidence and reported mortality. However, the risk between underdiagnosis-in the absence of specific invasive investigations, and with a consequent possible increase in mortality-and over-diagnosis (case identification with galactomannan on broncho-alveolar fluid alone) might be considered. Realistic incidence rates, based on local, real-life epidemiological data, might be helpful in guiding clinicians.