UMass Chan Medical School Faculty Publications

UMMS Affiliation

Department of Emergency Medicine, Department of Microbiology and Physiological Systems; Program in Microbiome Dynamics

Publication Date


Document Type

Article Preprint


Digestive System | Immunology and Infectious Disease | Infectious Disease | Medical Microbiology | Medical Physiology | Microbiology | Virus Diseases


Introduction In 2020, the world experienced the beginning of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), also known as the coronavirus disease 2019 (COVID-19) pandemic. Mounting evidence indicates that the gut microbiome plays a role in host immune response to infections and, in turn, may have an impact on the disease trajectory of SARS-CoV2 infection. However, it remains to be established whether modulation of the microbiome can impact COVID-19–related symptomatology and patient outcomes. Therefore, we conducted a study designed to modulate the microbiome evaluating the safety and physiologic effects of KB109 combined with self-supportive care (SSC) vs SSC alone in non-hospitalized patients with mild to moderate COVID-19. KB109 is a novel synthetic glycan developed to increase the production of gut microbial metabolites that support immune system homeostasis through gut microbiome modulation. Our goal was to gain a better understanding of the safety of KB109, the natural course of COVID-19 symptomatology, and the possible role of the gut microbiome in patients with mild to moderate COVID-19.

Methods Adult patients who tested positive for COVID-19 were randomized 1:1 to receive KB109 combined with SSC or SSC alone for 14 days and were then followed for an additional 21 days (35 days in total). Patients self-assessed their COVID-19–related symptoms (8 cardinal symptoms plus 5 additional symptoms) and self-reported comorbidities. The primary and secondary objectives were to evaluate the safety of KB109 plus SSC compared with that of SSC alone and to evaluate selected measures of health, respectively.

Results Between July 2, 2020 and December 23, 2020, 350 patients were randomized to receive KB109 and SSC (n=174) or SSC alone (n=176). Overall, the most common comorbidities reported were hypertension (18.0% [63/350 patients]) followed by chronic lung disease (8.6% 30/350 patients). KB109 was well tolerated with most treatment-emergent adverse events being mild to moderate in severity. The administration of KB109 plus SSC reduced medically-attended visits (ie, hospitalization, emergency room visits, or urgent care visits) by 50.0% in the overall population and by 61.7% in patients with ≥1 comorbidity; in patients aged ≥45 years or with ≥1 comorbidity, medically-attended visits were reduced by 52.8%, In the SSC group, patients reporting ≥1 comorbidity had a longer median time to resolution of symptoms than those who reported no comorbidities at baseline (13 overall symptoms: 30 vs 21 days, respectively; hazard ratio [HR]=1.163 [95% CI, 0.723-1.872]; 8 cardinal symptoms: 21 vs 15 days, respectively; HR=1.283 [95% CI, 0.809-2.035]). In patients reporting ≥1 comorbidity, median time to resolution of symptoms was shorter in the KB109 plus SSC group compared with the SSC alone group (13 overall symptoms: 30 vs 21 days, respectively; HR=1.422 [95% CI, 0.898-2.250]; 8 cardinal symptoms: 17 vs 21 days, respectively; HR=1.574 [95% CI, 0.997-2.485]). In the KB109 plus SSC group, patients aged ≥45 years or with ≥1 comorbidity had a shorter median time to resolution of symptoms compared with SSC alone (overall 13 symptoms: 21 vs 31 days; HR=1.597 [95% CI, 1.064-2.398]).

Conclusions Results from our study show that KB109 is well tolerated among patients with mild to moderate COVID-19. Patients with ≥1 comorbidity had a longer duration of COVID-19 symptoms than those without comorbidities. Moreover, in patients reporting ≥1 comorbidity or aged ≥45 years (at-risk population), administration of KB109 plus SSC improved median time to resolution of COVID-19–related symptoms and reduced the rate of medically-attended visits compared with SSC alone.


COVID-19, gut microbiome, KB109, metabolites

Rights and Permissions

The copyright holder for this preprint is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY-NC-ND 4.0 International license.

DOI of Published Version



medRxiv 2021.03.26.21254422; doi: Link to preprint on medRxiv.


This article is a preprint. Preprints are preliminary reports of work that have not been certified by peer review.

Journal/Book/Conference Title


Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.