ABSTRACT
Although the respiratory tract is the primary site of SARS-CoV-2 infection and the ensuing immunopathology, respiratory immune responses are understudied and urgently needed to understand mechanisms underlying COVID-19 disease pathogenesis. We collected paired longitudinal blood and respiratory tract samples (endotracheal aspirate, sputum or pleural fluid) from hospitalized COVID-19 patients and non-COVID-19 controls. Cellular, humoral and cytokine responses were analysed and correlated with clinical data. SARS-CoV-2-specific IgM, IgG and IgA antibodies were detected using ELISA and multiplex assay in both the respiratory tract and blood of COVID-19 patients, although a higher receptor binding domain (RBD)-specific IgM and IgG seroconversion level was found in respiratory specimens. SARS-CoV-2 neutralization activity in respiratory samples was detected only when high levels of RBD-specific antibodies were present. Strikingly, cytokine/chemokine levels and profiles greatly differed between respiratory samples and plasma, indicating that inflammation needs to be assessed in respiratory specimens for the accurate assessment of SARS-CoV-2 immunopathology. Diverse immune cell subsets were detected in respiratory samples, albeit dominated by neutrophils. Importantly, we also showed that dexamethasone and/or remdesivir treatment did not affect humoral responses in blood of COVID-19 patients. Overall, our study unveils stark differences in innate and adaptive immune responses between respiratory samples and blood and provides important insights into effect of drug therapy on immune responses in COVID-19 patients.
Subject(s)
COVID-19ABSTRACT
Introduction: The COVID-19 pandemic and restrictions placed on movement to prevent its transmission has led to a surge in demand for remote medical care. We investigated whether COVID-Care, a patient-reported telehealth symptom monitoring system, was successful at delivering safe monitoring and care for these patients leading to decreased hospital presentations.Methods: We performed a single centre, prospective, interventional cohort study with symptomatic outpatients who presented for COVID-19 screening at Austin Health, Australia. Participants were invited to take part in the COVID-Care program, entering common COVID-19 symptoms on a purpose-built, online survey monitored by infectious diseases physicians, and matched with clinical data including date of symptom onset, hospital admission, and screening clinic presentations. Results: 42,158 COVID-19 swabs were performed in 31,626 patients from March to October 2020, with 414 positive cases. 20,768 people used the COVID-Care survey at least once. COVID-Care users were significantly younger than non-users. Of the 414 positive cases, 254 used COVID-Care, with 160 non-users. Excluding presentations on the same day or prior to the COVID-19 swab, there were 56 hospital presentations. 4.3% of COVID-Care users and 28.1% non-users were admitted to hospital or the Emergency Department (p<0.001), with 3.9% vs 22.5% requiring inpatient admission (p<0.001). There were no deaths in COVID-Care users vs 2 deaths in non-users.Conclusion: COVID-Care, a digitally integrated, outpatient, symptom tracking and telemedical service for patients with COVID-19, was safe and successful at reducing hospital and emergency department admissions, suggesting a strong role for telemedicine for future healthcare delivery in this logistically challenging setting.Funding Statement: This work was supported by funding from the Austin Health Fundraising Department.Declaration of Interests: None declared.Ethics Approval Statement: Ethics approval: Austin Health; Audit 20/147.
Subject(s)
COVID-19 , EmergenciesABSTRACT
Background: In Australia, COVID-19 diagnosis relies on RT-PCR testing which is relatively costly and time-consuming. To date, no studies have assessed the performance and implementation of rapid antigen-based SARS-CoV-2 testing in a setting with a low prevalence of COVID-19 infections, such as Australia. Methods: This study recruited participants presenting for COVID-19 testing at three Melbourne metropolitan hospitals during a period of low COVID-19 prevalence. The Abbott PanBioTM COVID-19 Ag point-of-care test was performed alongside RT-PCR. In addition, participants with COVID-19 notified to the Victorian Government were invited to provide additional swabs to aid validation. Implementation challenges were also documented. Findings: The specificity of the Abbott PanBioTM COVID-19 Ag test was 99.96% (95% CI 99.73 - 100%). Sensitivity amongst participants with RT-PCR-confirmed infection was dependent upon the duration of symptoms reported, ranging from 78.9% (duration 1 to 33 days) to 100% in those within 7 days of symptom onset. A range of implementation challenges were identified which may inform future COVID-19 testing strategies in a low prevalence setting. Interpretation: Given the high specificity, antigen-based tests may be most useful in rapidly triaging public health and hospital resources while expediting confirmatory RT-PCR testing. Considering the limitations in test sensitivity and the potential for rapid transmission in susceptible populations, particularly in hospital settings, careful consideration is required for implementation of antigen testing in a low prevalence setting. Funding: This work was funded by the Victorian Department of Health and Human Services. The funder was not involved in data analysis or manuscript preparation.Declaration of Interests: All authors: no conflicts.Ethics Approval Statement: Ethics review and study approval was provided by Monash Health Human Research and Ethics Committee (RES-20-0000-678A) and local Governance approval was provided by Melbourne Health and Austin Health Offices for Research.