Dynamical Behavior of SEIR-SVS Epidemic Models with Nonlinear Incidence and Vaccination

For some infectious diseases such as mumps, HBV, there is evidence showing that vaccinated individuals always lose their immunity at different rates depending on the inoculation time. In this paper, we propose an age-structured epidemic model using a step function to describe the rate at which vaccinated individuals lose immunity and reduce the age-structured epidemic model to the delay differential model. For the age-structured model, we consider the positivity, boundedness, and compactness of the semiflow and study global stability of equilibria by constructing appropriate Lyapunov functionals. Moreover, for the reduced delay differential equation model, we study the existence of the endemic equilibrium and prove the global stability of equilibria. Finally, some numerical simulations are provided to support our theoretical results and a brief discussion is given.

Sudden death of COVID-19 patients in Wuhan, China: A retrospective cohort study.

BACKGROUND: In December 2019, coronavirus disease 2019 (COVID-19) emerged in Wuhan city and rapidly spread throughout China. So far, it has caused ~ 4000 deaths in this country. We aimed to systematically characterize clinical features and determine risk factors of sudden death for COVID-19 patients. METHODS: Deceased patients with COVID-19 in Tongji hospital from January 22 to March 23, 2020 were extracted. Patients who died within 24 hours after admission were identified as sudden deaths, and the others formed non-sudden deaths. The differences in clinical characteristics between the two groups were estimated. Risk factors associated with sudden deaths were explored by logistic regression. RESULTS: 281 deceased patients were enrolled in this study. Sudden death occurred in 28 (10.0%) patients, including 4 (14.3%) admitted to the intensive care unit. Fatigue was more common in sudden deaths (11, 47.8%) than in non-sudden deaths (40, 17.2%). Both the count and percentage of eosinophils were lower in sudden deaths than that in non-sudden deaths (P = 0.006 and P = 0.004). Compared with non-sudden deaths, sudden deaths had higher plasma levels of procalcitonin, C-reactive protein, D-dimer, alanine aminotransferase, aspartate aminotransferase, gamma-glutamyl transferase, lactate dehydrogenase, alkaline phosphatase and N-terminal pro-brain natriuretic peptide. There were not significant differences in gender, age, chest CT image features and comorbidities observed. CONCLUSIONS: The differences between the two groups suggested more severe systemic inflammation, multi-organ dysfunction, especially impaired liver and heart function in COVID-19 patients who died suddenly after admission. More researches are needed to verify these points.

Repurposed Tocilizumab in Patients with Severe COVID-19.

The coronavirus disease 2019 (COVID-19) has caused a global pandemic, resulting in considerable morbidity and mortality. Tocilizumab, an inhibitor of IL-6, has been widely repurposed as a treatment of severely ill patients without robust evidence supporting its use. In this study, we aimed to systematically describe the effectiveness of treatment and prevention of the cytokine storms in COVID-19 patients with tocilizumab. In this multicentered retrospective and observational cohort study, 65 patients with COVID-19 receiving tocilizumab and 130 not receiving tocilizumab were propensity score matched at a ratio of 2:1 based on age, sex, and comorbidities from January 20, 2020 to March 18, 2020 in Wuhan, China. After adjusting for confounding, the detected risk for in-hospital death was lower in the tocilizumab group versus nontocilizumab group (hazard ratio = 0.47; 95% confidence interval = 0.25-0.90; p = 0.023). Moreover, use of tocilizumab was associated with a lower risk of acute respiratory distress syndrome (odds ratio = 0.23; 95% confidence interval = 0.11-0.45; p < 0.0001). Furthermore, patients had heightened inflammation and more dysregulated immune cells before treatment, which might aggravate disease progression. After tocilizumab administration, abnormally elevated IL-6, C-reactive protein, fibrinogen, and activated partial thromboplastin time decreased. Tocilizumab may be of value in prolonging survival in patients with severe COVID-19, which provided a novel strategy for COVID-19-induced cytokine release syndrome. Our findings could inform bedside decisions until data from randomized, controlled clinical trials become available.

Obesity predisposes to the risk of higher mortality in young COVID-19 patients. (Special issue on new coronavirus (2019-nCoV or SARS-CoV-2) and the outbreak of the respiratory illness (COVID-19): part-VII.)

Although emerging data demonstrated mortality of young COVID-19 patients, no data have reported the risk factors of mortality for these young patients, and whether obesity is a risk for young COVID-19 patients remains unknown. We conducted a retrospective study including 13 young patients who died of COVID-19 and 40 matched survivors. Logistic regression was employed to characterize the risk factors of mortality in young obese COVID-19 patients. Most of the young deceased COVID-19 patients were mild cases at the time of admission, but the disease progressed rapidly featured by a higher severity of patchy shadows (100.00% vs 48.70%;P = .006), pleural thickening (61.50% vs 12.80%;P = .012), and mild pericardial effusion (76.90% vs 0.00%;P < .001). Most importantly, the deceased patients manifested higher body mass index (odds ratio [OR] = 1.354;95% confidence interval [CI] = 1.075-1.704;P = .010), inflammation-related index C-reactive protein (OR = 1.014;95% CI = 1.003-1.025;P = .014), cardiac injury biomarker hs-cTnI (OR = 1.420;95% CI = 1.112-1.814;P = .005), and increased coagulation activity biomarker D-dimer (OR = 418.7;P = .047), as compared with that of survivors. Our data support that obesity could be a risk factor associated with high mortality in young COVID-19 patients, whereas aggravated inflammatory response, enhanced cardiac injury, and increased coagulation activity are likely to be the mechanisms contributing to the high mortality.

Clinical characteristics of COVID-19 patients with asthma in Wuhan, China: a retrospective cohort study.

OBJECTIVE: Although it is reported that patients with coronavirus disease 2019 (COVID-19) disease who have comorbidities are at higher risk to suffer adverse clinical outcomes, there are inadequate evidence to clarify the association between COVID-19 and asthma. On this ground, this study aims to systematically analyze the clinical characteristics of COVID-19 patients with asthma. METHODS: In this single-center, retrospective and observational cohort study, 21 COVID-19 patients with asthma and 100 non-asthma COVID-19 patients were statistically matched by propensity score based on age, sex and comorbidities. Meanwhile, a collection and comparison concerning demographic indicators, clinical and laboratory examinations, treatments and outcomes were conducted between two groups to specify their differences. RESULTS: Statistically, the COVID-19 patients with asthma had a higher proportion of ICU admission (14.3% [3/21] vs. 2.1% [2/96] p = 0.040) than those who do not have. On top this, a higher level of inflammatory responses, such as interleukin 6, interleukin 8, procalcitonin, leukocytes, neutrophils and CD4+ T cells was presented in asthma patients. Moreover, the increase of organ damage indices like D-dimer, lactate dehydrogenase and high-sensitivity cardiac troponin I, were more pronounced in COVID-19 patients with asthma. CONCLUSIONS: Exacerbated inflammatory responses and multiple organ damages were triggered in COVID-19 patients with asthma, which highlights more intensive surveillance and supportive treatment.

Outpatient strategies and the changing SARS-CoV-2 epidemic.

In response to the early outbreak of SARS-CoV-2, online fever clinics were set up. Then, an online face-to-face consultation was developed to solve the extreme difficulty of getting medical services to patients with chronic diseases. http://bit.ly/3cPppai.

Clinical characteristics of 54 medical staff with COVID-19: A retrospective study in a single center in Wuhan, China.

In December 2019, an outbreak of the severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2) infection occurred in Wuhan, and rapidly spread to worldwide, which has attracted many people's concerns about the patients. However, studies on the infection status of medical personnel is still lacking. A total of 54 cases of SARS-Cov-2 infected medical staff from Tongji Hospital between 7 January and 11 February 2020 were analyzed in this retrospective study. Clinical and epidemiological characteristics were compared between different groups by statistical method. From 7 January to 11 February 2020, 54 medical staff of Tongji Hospital were hospitalized due to coronavirus disease 2019 (COVID-19). Most of them were from other clinical departments (72.2%) rather than emergency department (3.7%) or medical technology departments (18.5%). Among the 54 patients with COVID-19, the distribution of age had a significant difference between non-severe type and severe/critical cases (median age: 47 years vs 38 years; P = .0015). However, there was no statistical difference in terms of gender distribution and the first symptoms between theses two groups. Furthermore, we observed that the lesion regions in SARS-Cov-2 infected lungs with severe-/critical-type of medical staff were more likely to exhibit lesions in the right upper lobe (31.7% vs 0%; P = .028) and right lung (61% vs 18.2%; P = .012). Based on our findings with medical staff infection data, we suggest training for all hospital staff to prevent infection and preparation of sufficient protection and disinfection materials.

Obesity predisposes to the risk of higher mortality in young COVID-19 patients

BACKGROUND: Although emerging data demonstrated mortality of young COVID-19 patients, but no data reported the risk factors of mortality for those young patients, and whether obesity is a risk for young COVID-19 patients remains unknown. METHODS: We conducted a retrospective study including 13 young patients died of COVID-19 and 40 matched survivors. Logistic regression was employed to characterize the risk factors of mortality in young obese COVID-19 patients. RESULTS: Most of the young deceased COVID-19 patients were mild cases at the time of admission, but the disease progressed rapidly featured by the higher severity of Patchy shadows (100.00% vs. 48.70%, P = 0.006), pleural thickening (61.50% vs. 12.80%, P = 0.012), mild pericardial effusion (76.90% vs. 0.00%, P < 0.001). Most importantly, the deceased patients manifested higher BMI (OR = 1.354, 95% CI = 1.075-1.704, P = 0.010), inflammatory-related index CRP (OR = 1.014, 95% CI = 1.003-1.025, P = 0.014), cardiac injury biomarker hs-cTnI (OR = 1.420, 95% CI = 1.112-1.814, P = 0.005), and increased coagulation activity biomarker D-Dimer (OR = 418.7, P = 0.047), as compared to that of survivors. CONCLUSIONS: Our data support that obesity could be a risk factor associated with high mortality in young COVID-19 patients, while aggravated inflammatory response, enhanced cardiac injury and increased coagulation activity are likely to be the mechanisms contributing to the high mortality. This article is protected by copyright. All rights reserved.