Several biomarkers have been evaluated as predictors of severity or in directing the treatment of COVID-19, however there are no conclusive results with prediction of the pathobiology of the infection. In this study, we evaluated serum levels of cytokines, chemokines, and cell growth factors in association with the pathobiology of mild to moderate SARS-CoV-2 infection. Those markers may act as immuno-inflammatory biomarkers in adults with mild to moderate flu syndrome who sought care at health units. Serum levels of SARS-CoV-2 infected patients (n=113) and flu symptoms individuals negative for SARS-CoV-2 (n=58), tested by the RT-qPCR test - nasal swab were compared to healthy controls (n=53). Participants who were symptomatic but negative for SARS-CoV-2 were tested for Influenza A/B and Respiratory Syncytial Virus (RSV). Results showed that the pro-inflammatory cytokines IL-1β, MCP-3, TNF-α and G-CSF were increased in symptomatic patients and the cytokines IL-6 and IL-10 were associated with patients positive for SARS-CoV-2 when compared to healthy controls. Symptoms associated with COVID-19 were fever, anosmia, ageusia and myalgia. For patients without SARS-CoV-2 infection their major symptom was sore throat. Five percent (4/83) of SARS-CoV-2 negative patients were positive for RSV. The pathobiology of mild to moderate SARS-CoV-2 infection was associated with increasing pro-inflammatory cytokines and also a pleiotropic IL-6 and anti-inflammatory IL-10 cytokines compared to healthy controls.

Treatment options for mild to moderate COVID-19 is limited. N-acetylcysteine and bromhexine have antiviral activity and show potential as treatment options against SARS-CoV-2 infections. This study evaluates the in vitro antiviral effect of bromhexine (BMX) for SARS-CoV-2 and determines the efficacy of treatment with BMX in combination with N-acetylcysteine (NAC) to reduce clinical scores in patients with mild to moderate COVID-19. Upon evidence from pre-clinical studies, a single center randomized trial of BMX + NAC (ClinicalTrials.gov Identifier: NCT04928495) with 420 participants in total took place in Fortaleza, CE, Brazil. Out of the 420 participants 140 received placebo, 140 received NAC alone, and 140 received NAC + BMX. Patients were monitored for 10-14 days, where physicians recorded all signs and symptoms reported. Nasopharyngeal swabs and blood samples were collected for SARS-CoV-2 RNA testing during the first visit, as well as 3 and 10 days after. Blood samples were collected at first visit and 10 days after for immuno-inflammatory biomarkers measurements. Treatment with NAC+BMX reduced clinical scores and symptoms when compared to placebo group (2/26; 8% vs 7/18; 39%; p < 0.05). Fever (≥37.8°C) was reduced by NAC + BMX treatment when compared to treatment with NAC alone and placebo. This study was limited by a largely vaccinated population. Our analysis showed that BMX reduces SARS-CoV-2 infection in vitro. Clinical trial results suggested that combinatory treatment with NAC + BMX is beneficial in mild to moderate COVID-19.