Secondary Infections in COVID-19 and their Impact on Disease Severity | Karius
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Secondary Infections in COVID-19 and their Impact on Disease Severity

As infectious disease physicians, we understand that significant efforts from healthcare workers are being made to help patients during the COVID-19 pandemic. While the Karius Test does not detect RNA viruses such as SARS-CoV-2, clinicians are utilizing the Karius® Test to help diagnose other infections quickly and non-invasively to enable targeted care to their patients.  


“We have seen that clinicians are using the Karius Test to avoid aerosol-generating procedures that might unnecessarily expose healthcare workers to SARS-CoV-2 or other pathogens. The Karius Test, although it does not detect SARS-CoV-2, has been useful for the evaluation of superinfections in those that have COVID-19.” William La Via, MD, Karius Medical Director


As we hear from our colleagues about their experiences, emerging data from the U.S., France, Spain, Singapore, and China describe co-occurring pathogens such as other respiratory viruses, bacteria, and fungi in patients with COVID-19.1-10 The prevalence of secondary infections has ranged from approximately 10-40%.1-10 Bacterial pathogens detected have included Klebsiella, Pseudomonas, and Acinetobacter, and fungal pathogens have included different species of Aspergillus. Notably, the use of immunomodulators may also raise the risk of secondary infections.11 Maintaining vigilance for the presence of secondary infections is critical. While the presence of secondary infections can impact morbidity and length of hospital or ICU stay, some data suggest that the presence of these additional infections may also be a predictor of mortality in patients with COVID-19.6,7,9,10


Many studies are ongoing for curative or disease-modifying antiviral therapies for COVID-19. Prompt diagnosis of secondary infections and administration of targeted, proven therapies for secondary infections may help prevent excess mortality in this pandemic. 


Karius is pursuing partnerships with leading institutions that have established COVID-19 research programs to answer questions related to secondary infections in patients with COVID-19. The goal is to evaluate the association between secondary infections, as detected by the Karius Test, and disease severity in patients with COVID-19. 


The Karius Test is a non-invasive blood test based on next-generation sequencing of microbial cell-free DNA that can identify and quantify over 1,000 clinically relevant pathogens including bacteria, DNA viruses, fungi, and parasites, directly from a single blood sample. We believe that utilizing the Karius Test will enable a comprehensive and rapid identification of microorganisms potentially causing secondary infections in hospitalized patients with COVID-19. 


Across a range of clinical indications, including in complicated pneumonia, published studies have demonstrated that the Karius Test results in a higher diagnostic yield of microorganisms when compared to blood culture and other microbiological testing, including from invasively obtained specimens.12-15 


Additionally, given the risk of SARS-CoV-2 transmission to healthcare workers by performing invasive diagnostic procedures such as a bronchoscopy, utilizing a non-invasive blood test, such as the Karius Test to diagnose infections, may reduce risk of exposure and transmission.


We welcome the opportunity to collaborate with additional institutions that have an active COVID-19 research program, and that are interested in evaluating secondary infections in patients with COVID-19. For additional information, please contact us at


Karius Medical Affairs



1 Barrasa H, et al. Anaesth Crit Care Pa 2020;S2352556820300643. [Epub ahead of print]

2 Chen N, et al. Lancet  2020;395(10223):507-513. 

3 Fan B.E., et al. Am. J. Hematol 2020. [Epub ahead of print]

4 Kim D, et al. JAMA 2020.[Epub ahead of print]

5 Lescure F.X., et al. Lancet Infect Dis 2020;S1473309920302000. [Epub ahead of print]

6 Ruan Q, et al. Intensive Care Med 2020. 

7 Wang L, et al. J Infect 2020;S0163445320301468. [Epub ahead of print]

8 Wu X, et al. Emerg Infect Dis 2020;26(6).

9 Yang X, et al. Lancet 2020;S2213260020300795. [Epub ahead of print]

10  Zhou F, et al. Lancet 2020;395(10229):1054-62. 

11 Bhimraj A, et al. “Infectious Diseases Society of America Guidelines on the Treatment and Management of Patients with COVID-19,”. Accessed April 22, 2020.

12 Farnaes L, et al. Diagn Microbiol Infect Dis 2019;94(2):188-191. 

13 Rossoff J, et al. Open Forum Infect Dis 2019;6(8):ofz327. 

14 Blauwkamp T, et al. Nat Microbiol 2019;4(4):663-674.

15 Hong D, et al, Diagn Microbiol Infect Dis. 2018;92(3):210-213.