ABSTRACT
SARS-COV-2 (Coronavirus) viral growth kinetics within-host become a key fact to understand the COVID-19 disease progression and disease severity since the year 2020. Quantitative analysis of the viral dynamics has not yet been able to provide sufficient information on the disease severity in the host. The SARS-CoV-2 dynamics are therefore important to study in the context of immune surveillance by developing a mathematical model. This paper aims to develop such a mathematical model to analyse the interaction between the immune system and SARS-CoV-2 within the host. The model is developed to explore the viral load dynamics within the host by considering the role of natural killer cells and T-cell. Through analytical simplifications, the model is found well-posed and asymptotically stable at disease-free equilibrium. The numerical results demonstrate that the influx of external natural killer (NK) cells alone or integrating with anti-viral therapy plays a vital role in suppressing the SARS-CoV-2 growth within-host. Also, within the host, the virus can not grow if the virus replication rate is below a threshold limit. The developed model will contribute to understanding the disease dynamics and help to establish various potential treatment strategies against COVID-19. © 2022 the Author(s), licensee AIMS Press.
ABSTRACT
Background: The declining trend of COVID-19 infection in India has made healthcare personnel (HCP) and general public lenient about personal-protective-measures. Serosurveys to estimate the prevalence of SARS-CoV2 IgG antibodies, particularly in high-risk-zones like hospitals can give the real scenario and risk-factors can help prioritise the target population for urgent, effective vacccination. Methods: 1470 consecutive HCP from 4 tertiary-care-hospitals in Kolkata filled a questionnaire and were tested for serum SARS-CoV2-IgG by Enzyme-linked Immunosorbent Assay (ELISA). The prevalence of SARS-CoV2-IgG among asymptomatic HCPs was studied and the work environment, clinical comorbidities, personal habits and protective measures and pharmacologic prophylaxes were compared between those with and without SARS-CoV2-IgG. Parameters of asymptomatic seroconverters were also compared to those with personal history of COVID-19-Infection. Logistic regression was done to identify independent risk-factors. Results: Prevalence of asymptomatic seroconversion was 15.8%. Asymptomatic seroconverters (n=208) were mostly working in mixed hospitals (having both COVID-19 and non-COVID-19 wards, 57.7%), were non-doctors by profession (nurses-25.1%, others–51.4%). Among asymptomatic HCP, indepedendent positive risk factors for SARS-CoV2 IgG-positivity were Diabetes Mellitus (DM) and multiple comorbidities (pboth <0.001) and prophylactic use of Hydroxychloroquine and Famotidine (pboth < 0.03). However, for symptomatic COVID-19 infection, working in COVID-19 dedicated hospitals, and personal h/o COPD were positive risk-factors and Ivermectin prophylaxis a negative risk-factor (pall < 0.03). Conclusion:In our study conducted i n the i mmedi ate pre-i mmuni sati on peri od, rate of asymptomati c seroconversion among HCPs is too low to presume herd immunity. Those working in mixed hospitals and DM, multiple comorbidities are at particularly high risk.
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Introduction: Currently the main diagnostic modality for COVID-19 (Coronavirus disease-2019) is reverse transcriptase polymerase chain reaction (RT-PCR) via nasopharyngeal swab which has high false negative rates (diagnostic yield∼70%). We evaluated the performance of high-resolution computed tomography (HRCT) imaging in the diagnosis of suspected COVID-19 infection compared to RT-PCR nasopharyngeal swab alone in patients hospitalized for suspected COVID-19 infection. Methods: This was a retrospective analysis of 324 consecutive patients admitted to Temple University Hospital. All hospitalized patients who had RT-PCR testing and HRCT were included in the study. HRCTs were classified as Category 1, 2 or 3. Category 1 scans were high probability scans (i.e: ground glass opacities (GGOs), crazy-paving, reverse halo/peri lobular pattern irrespective of location and laterality). Category 3 were low probability scans consistent with an alternate diagnosis. Category 2 scans were indeterminate. Patients were then divided into four groups based on HRCT category and RT-PCR swab results for analysis (Group 1: COVID (+) PCR and Category 1 CT scan, Group 2: COVID (+) PCR and Category 2 and 3 CT scan, Group 3: COVID (-) PCR and Category 1 CT scan, Group 4: COVID (-) PCR and Category 2 and 3 CT scan). Inflammatory markers and treatments were compared across these groups. Results: The average age of patients was 59.4(+15.2) years and 123(38.9%) were female. Predominant ethnicity was African American 148 (46.11%). 161 patients tested positive by RT-PCR, while 41 tested positives by HRCT. 167 (52.02%) had category 1 scan, 63 (19.63%) had category 2 scan and 91 (28.35%) had category 3 HRCT scans. There was substantial agreement between our radiologists for HRCT classification (κ = 0.64). Sensitivity and specificity of HRCT classification system was 77.6 and 73.7 respectively. 38.9 % (n=125) patients were classified as Group 1);11.2% (n=36) as Group 2, 12.8% (n=41) as Group 3 and 34.8 % (n=115) as Group 4. In group 3, 38 (92.7 %) patients received respiratory viral panels (RVP) which were all negative;21(51.2%) had sputum cultures, only 1 was positive for staph aureus. When comparing Group 1 to Group 3, there were no statistically significant differences in inflammatory markers. There were no statistically significant differences amongst Groups 1 and 3 with respect to treatments Conclusion: Due to its high infectivity and asymptomatic transmission, until a highly sensitive and specific COVID-19 test is developed, HRCT is a valuable assessment tool for patients who are hospitalized with suspected COVID-19.
ABSTRACT
Rationale: Coronavirus disease 2019 (COVID-19) has provoked an unprecedented global pandemic. Invasive mechanical ventilation (IMV) rates in COVID-19 have been reported to be from 2.3% to 33%. The wide range in reported intubation rates is attributed in part to diverging institutional practices for the care of patients presenting with hypoxemic respiratory failure. The role of high flow nasal therapy (HFNT) in the treatment of COVID-19 has been controversial and underreported. Objectives: To report a retrospective analysis comparing the outcomes of patients treated with HFNT and IMV for hypoxemic respiratory failure secondary to COVID-19. Methods: This was an analysis of consecutive patients admitted to Temple University Hospital between March 10, 2020, and May 17, 2020, for moderate to severe hypoxemic respiratory failure from COVID-19 pneumonia. Patients were divided into three groups: IMV group-not placed on HFNT prior to intubation. HFNT group-received only HFNT. HFNT to intubation group-received HFNT prior to intubation. Comparisons were made between demographics, baseline laboratory values, and outcomes. Results: 1396 patients admitted to Temple University Hospital between March 10, 2020, and May 17, 2020 with suspected COVID-19 infection were retrospectively screened for this study. 837 patients tested positive for COVID-19 by nasopharyngeal RT-PCR or deemed positive based on clinical features. There were no statistically significant differences in terms of demographics between all three groups. However, the intubation and HFNT to intubation groups had a higher incidence of malignancy compared to the HFNT only group. There was a higher incidence of smoking in the intubation group (59.2%) and HFNT to intubation group (53.7%) compared to HFNT only group (29.2%). Laboratory data were similar between all three groups besides admission BUN/creatinine. In terms of therapies, high-dose steroids were administered more frequently to patients in the HFNT (84.3%) and HFNT to intubation (90.2%) groups compared to the intubated group (56.5%). Overall, 49 (28.1%) were intubated, 84 (48.2%) were treated with HFNT only, and 41 (23.5%) progressed from HFNT to intubation. The mortality was 36.7% in the intubation group, 6% in the HFNT only group, and 43.9% in the HFNT to intubation group. Overall mortality was 25.7%. Conclusion: Our institutional decision to utilize HFNT as the primary treatment for moderate to severe hypoxemic respiratory failure led to a low intubation rate thus reducing overall morbidity and mortality. In the appropriate clinical context HFNT should be the considered the oxygen modality of choice in moderate to severe hypoxemic respiratory failure secondary to COVID-19 pneumonia.
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Introduction Use of high flow nasal therapy (HFNT) to treat COVID-19 pneumonia has been greatly debated around the world due to concern for increased healthcare worker transmission and delays in invasive mechanical Ventilation (IMV). Herein we analyze the utility of the ROX index to predict the need and timing for IMV in a retrospective analysis of patients with COVID-19 with moderate to severe hypoxemic respiratory failure treated with HFNT. Methods This was a retrospective analysis of 129 consecutive patients with COVID-19 admitted to Temple University Hospital in Philadelphia, Pennsylvania, from March 10, 2020, to May 17, 2020 with moderate to severe hypoxemic respiratory failure treated with High Flow nasal therapy (HFNT). HFNT patients were divided into two groups: HFNT only and HFNT progressed to IMV. The primary outcome was the ability of the ROX index to predict the need of IMV. Secondary outcomes were mortality, rates of intubation, length of stay (LOS) and rates of nosocomial infections in our cohort treated with HFNT were also reported. Results 837 patients with COVID-19 were screened, 129 met inclusion criteria. The mean age was 60.8(+13.6) years, BMI 32.6(+8), 58(45 %) were female, 72(55.8%) were African American, 40 (31%) Hispanic. 48 (37.2%) were smokers. Of the 129, 89 were HFNT only group whereas 40 in the HFNT progressed to IMV group. Mean time to intubation was 2.5 days(+ 3.3). The 89 HFNT only patients had a significant improvement in ROX from initiation of HFNT at all recorded time points. In contrast, the ROX in HFNT progressed to IMV patients remained unchanged or decreased over time. ROX index of less than 5 at HFNT initiation was predictive of progression to IMV (OR = 2.137, p = 0,052). Any decrease in ROX index after HFNT initiation was predictive of intubation (OR= 14.67, p <0.0001). In multivariate analysis, ΔROX (<=0 versus >0), peak D-dimer >4000 and admission GFR < 60 ml/min were very strongly predictive of need for IMV (ROC = 0.86, p=0.001). Mortality was 11.2% in HFNT only group versus 47.5% in the HFNT progressed to IMV group (p = 0.0001). Mortality and need for pulmonary vasodilators were higher in the HNFT progressed to IMV group. Conclusion ROX index is a valuable, noninvasive tool to evaluate patients with moderate to severe hypoxemic respiratory failure in COVID-19 treated with HFNT. ROX helps predicts need for IMV and thus limiting morbidity and mortality associated with IMV.