Thoughts on diagnosis and treatment plan of patients infected with severe acute respiratory syndrome coronavirus 2 omicron variant in large shelter hospitals in Shanghai.

The epidemic caused by the infection of severe acute respiratory syndrome coronavirus 2 omicron variant broke out in Shanghai in Mar. 2022. Omicron variant has characteristics such as strong concealment and rapid transmission, resulting in significant differences between the current round of epidemic and that in Wuhan. The number of infected patients (mainly asymptomatic infected patients) increased rapidly in a short term. Based on dynamic zero policy, shelter hospitals were set up in time in Shanghai to treat the patients. It is suggested that medical resources and patient characteristics should be taken into account in the independent cabin of a shelter hospital with more than 10 000 beds, and the clinical medical practice should be divided to 5 modes (universal education and management, community outpatient clinic, ward duty, emergency rescue, and temporary observation and transport) to optimize the allocation of medical resources, so as to further enhance the treatment capacity and efficiency of shelter hospitals.Copyright © 2022, Second Military Medical University Press. All rights reserved.

Preoperative COVID-19 RT-PCR Testing of Asymptomatic Patients for Ophthalmic Surgery: Experience from Two Tertiary Referral Centers

Purpose: The aim of this study was to evaluate how prevalent asymptomatic SARS-CoV-2 virus infection (COVID-19) is among patients undergoing ophthalmic surgery at two tertiary referral hospitals. Material(s) and Method(s): This retrospective study included patients without COVID-19 symptoms who underwent preoperative screening using reverse transcription-polymerase chain reaction (RT-PCR) before ophthalmic surgery at the Kocaeli University and Gaziantep University departments of ophthalmology [between September 1, 2020, and December 15, 2020 (group 1);between March 1, 2021, and May 30, 2021 (group 2)]. Patients scheduled for surgery and followed up in the retina, glaucoma, pediatric ophthalmology and strabismus, cataract and refractive surgery, and cornea departments were examined. Result(s): RT-PCR was positive for SARS-CoV-2 in 12 (1.4%) of 840 patients in group 1 and 7 (1.1%) out of 600 patients in group 2. None of the patients were symptomatic of COVID-19. The majority of the patients were scheduled for retina or cataract and refractive surgery in both groups (group 1;retina: 29.2%, cataract and refractive: 57.0%, group-2;retina: 31.3%, cataract and refractive: 54.5%). SARS-CoV-2 RT-PCR testing was positive for seven patients in group 1 (7/245, 2.9%) and five patients in group 2 (5/188, 2.6%) who were scheduled for retinal surgery. Conclusion(s): The necessity, availability, and practicality of COVID-19 RT-PCR testing prior to ophthalmic surgeries varies depending on the protocols of each institution. COVID-19 RT-PCR testing is suggested especially before vitreoretinal surgeries and general anesthesia procedures, because of the difficulty in managing postoperative complications.Copyright © 2023 Gazi Eye Foundation. All rights reserved.

Covid-19: Is the placenta a safe space

Problem: Several large studies have demonstrated that COVID-19 pregnant individuals are at a significant risk for severe disease and adverse pregnancy outcomes. The mechanisms underlying these phenomena remain to be elucidated and are the focus of our project. Although fetal and placental infection is rare, placental abnormalities and adverse pregnancy outcomes associated with placental dysfunction in COVID-19 cases have been widely reported. In particular, placental thrombosis and lesions consistent with maternal vascular malperfusion (MVM) of the placenta are common in individuals with COVID-19. Since thrombotic complications have been associated with COVID-19, it is not surprising that pregnant individuals with COVID- 19 are at risk for placental thrombosis. Method of Study: Placentas were evaluated histologically. Extracellular vesicles were isolated by serial centrifugation. Result(s): Adverse pregnancy outcomes associated with these placental lesions, including hypertensive disorders of pregnancy (gestational hypertension and preeclampsia), small for gestational age (SGA, birthweight < 10th percentile for gestational age), and preterm birth (PTB, < 37 weeks) are significantly increased among pregnant individuals with COVID-19. Placental infection with SARSCoV- 2 is uncommon, but multiple inflammatory and metabolic factors are likely to affect the placenta, including circulating extracellular vesicles (EVs) derived from various organs that have been associated with COVID-19 pathology and disease severity.We have analyzed over 500 placentas from COVID-19 pregnancies and found marked changes in placental morphology, characterized by abnormal maternal and fetal vessels, intervillous thrombi, and fibrin deposition, even in the face of mild or asymptomatic disease. We detected increased levels of small EVs in maternal serum from COVID-19 cases compared to controls and increased levels of mitochondrial DNA in EVs from COVID-19 cases. In in vitro experiments, we found increased oxidative stress in uterine endothelial cells and primary trophoblasts. Syncytialization of trophoblast cells following exposure to EVs from pregnant COVID-19 patients was markedly reduced. RNAseq of trophoblast cells exposed to EVs from pregnant COVID-19 patients revealed disruption of multiple pathways related to mitochondria function, oxidative stress, coagulation defects, and inflammation. Timing of infection during pregnancy (first, second, and third trimester) altered EV size distribution, cargo content, and functional consequences of trophoblast EV exposure. Conclusion(s): Our studies show that COVID-19 infection during pregnancy has profound effects on placenta morphology and function. It remains to be determined what the long-term consequences are on the offspring.

Anti-SARS-CoV-2 antibodies important in diagnostics of acute hepatitis in children

The most common causes of acute hepatitis in children are hepatitis A and autoimmune hepatitis. Hepatitis in the course of Wilson's disease is sporadically registered in adolescents. An increase of activity of aminotransferases both in the course of multisystem inflammatory syndrome in children (MIS-C) and in the course of COVID-19 has been observed. Hepatitis is common in children with MIS-C and is associated with a more severe presentation and persistent elevation of liver function tests. To date, no cases of acute hepatitis in children due to COVID-19 have been reported. We present 2 cases of acute hepatitis in children where the only cause seems to be a previous asymptomatic SARS-CoV-2 infection.Copyright © 2023 Termedia Publishing House Ltd.. All rights reserved.

SARS-CoV-2 infection (COVID-19) in children.

Since the outbreak in December 2019, the SARS-CoV-2 pandemic virus has been a major public health problem in all countries of the world. The virus is transmitted by inhalation of respiratory droplets from the patient or asymptomatic carrier and is highly contagious. The clinical disease in children is similar to any acute respiratory infection with predominant upper respiratory symptoms, but occasionally can progress to pneumonia with acute respiratory distress syndrome and multiorgan failure. The disease is milder in children than in adults, with low mortality, and it appears that infants and young children have a somewhat more severe clinical course. Diagnosis is made by detecting the virus from respiratory samples (mainly nasopharyngeal and oropharyngeal swabs) using polymerase chain reaction. Treatment is usually symptomatic, and in severe and critical forms, the use of one of the antiviral drugs (lopinavir-ritonavir, remdesivir, hydroxychloroquine) may be consideredCopyright © 2020 Croatian Paediatric Society. All rights reserved.

COVID-19 SYMPTOMS AND DISEASE COURSE IN GERMAN PEDIATRIC RHEUMATOLOGY PATIENTS REPORTED TO BIKER

BackgroundCOVID-19 has shaped the world over the last 3 years. Although the risk for severe COVID-19 progression in children is low it might be aggravated by chronic rheumatic disease or treatment with immunosuppressive drugs.ObjectivesWe analyzed clinical data of COVID-19 cases among paediatric patients with rheumatic diseases reported to BIKER between March 2020 and December 2022.MethodsThe main task of the German BIKER (Biologics in Pediatric Rheumatology) registry is safety monitoring of biologic therapies in JIA. After the onset of the COVID-19 pandemic, the survey was expanded with a standardized form to proactively interview all participating centers about occurrence, presentation and outcome of SARS-CoV-2 infections in children with rheumatic diseases.ResultsA total of 68 centres participated in the survey. Clinical data from 928 COVID infections in 885 patients with rheumatic diseases could be analyzed. JIA was the most common diagnosis with (717 infections), followed by genetic autoinflammation (103 infections), systemic autoimmune diseases (78 infections), idiopathic uveitis (n=25), vasculitis (n=5).In 374 reported COVID infections (40%), patients were receiving conventional DMARDs, in 331 (36%) biologics, mainly TNF inhibitors (TNFi, n=241 (26%)). In 567 reports (61%) patients used either a biologic or a DMARD, in 339 reports patients (37%) did not use any antirheumatic medication including steroid.Over the last 3 years, COVID-19 occurred in Germany in 5 distinguishable waves, calendar weeks (CW) 10-30 in 2020, CW 21/2020 – 8/2021(both predominantly wild-type variant), CW 9-27 in 2021 (Alpha variant in the majority of infections), CW 28-51 in 2021 (Delta variant), since CW 52/2021 (several Omikron variants;Robert-Koch Institute: VOC_VOI_Tabelle.xlsx;live.com))In our cohort, patients with SARS-CoV-2 infection were slightly older during the 1st and 2nd wave (mean age 12.7+/-3.5 and 12.8+/-4.3 years) compared to the 4th and 5th wave with 11.4+/-3.9 and 11.4+/-4.2 years;p=0.01.160 asymptomatic SARS-CoV-2 infections were reported, frequencies of symptoms associated with COVID-19 are shown in table 1.Five patients were hospitalized for 4-7 days. A 3½-year-old female patient succumbed during the first wave with encephalopathy and respiratory failure. The patient had been treated with MTX and steroids for systemic JIA. Genetic testing revealed a congenital immunodeficiency. No other patient needed ventilation or intensive care. One case of uncomplicated PIMS in an MTX treated JIA patient was reported.The duration of SARS-CoV-2 infection-associated symptoms was markably shorter during the 5th wave with 6.7+/-5.1 days, compared with reports from the other 4 waves (Table1).The duration of symptoms was higher in MTX treated patients (10.2+/-8.4 days) compared to patients without treatment (7.7+/-10.8;p=0.004) or patients treated with TNFi (8.2+/-4.8, p=0.002). Although patients treated with steroids also had a longer duration of symptoms (9.7+/-7.0), this was not significant.ConclusionExcept for one patient with congenital immunodeficiency who died, no case of severe COVID-19 was reported in our cohort. At the time of infection, over 60% of patients had been treated with conventional DMARDs and/or biologics. Although MTX treated patients had a slightly longer duration of symptoms, antirheumatic treatment did not appear to have a negative impact on severity or outcome of SARS-CoV-2 infection.Table 1.Characteristics and frequency of symptoms in SARS-CoV-2 infectionsN or mean (SD)1st wave N=202nd wave N=843rd wave N=384th wave N=1245th wave N=662female14532775432age at COVID-19, years12.7 (3.5)12.8 (4.3)11.8 (3.5)11.4 (3.9)11.4 (4.2)asymptomatic126132694duration of symptoms;days,11.9 (14.7)9.2 (7.0)14.1 (11.6)10.3 (7.6)6.7 (5.1)fever1218541306cough1015652245rhinitis5261344289headache4161227171sore throat61139132musculosceletal pain2751348loss of smell/taste71162113fatigue4882680dizziness122116gastrointestinal symptoms151864dyspnea1117pneumonia11bronchitis1REFERENCES:NIL.Acknowledgements:NIL.Disclosure of Inter stsAriane Klein Speakers bureau: Novartis, Toni Hospach Speakers bureau: Speaking fee Novartis and SOBI., Frank Dressler Speakers bureau: Abbvie, Novartis, Pfizer, Advisory Boards Novartis and Mylan, Daniel Windschall Grant/research support from: research funds by Novartis, Roche, Pfizer, Abbvie, Markus Hufnagel: None declared, Wolfgang Emminger: None declared, Sonja Mrusek: None declared, Peggy Ruehmer: None declared, Alexander Kühn: None declared, Philipp Bismarck: None declared, Maria Haller: None declared, Gerd Horneff Speakers bureau: Pfizer, Roche, MSD, Sobi, GSK, Sanofi, AbbVie, Chugai, Bayer, Novartis, Grant/research support from: Pfizer, Roche, MSD, AbbVie, Chugai, Novartis.

Analysis of the COVID19 Pandemic Behaviour Based on the Compartmental SEAIRD and Adaptive SVEAIRD Epidemiologic Models

A significant number of people infected by COVID19 do not get sick immediately but become carriers of the disease. These patients might have a certain incubation period. However, the classical compartmental model, SEIR, was not originally designed for COVID19. We used the simple, commonly used SEIR model to retrospectively analyse the initial pandemic data from Singapore. Here, the SEIR model was combined with the actual published Singapore pandemic data, and the key parameters were determined by maximizing the nonlinear goodness of fit R2 and minimizing the root mean square error. These parameters served for the fast and directional convergence of the parameters of an improved model. To cover the quarantine and asymptomatic variables, the existing SEIR model was extended to an infectious disease model with a greater number of population compartments, and with parameter values that were tuned adaptively by solving the nonlinear dynamics equations over the available pandemic data, as well as referring to previous experience with SARS. The contribution presented in this paper is a new model called the adaptive SEAIRD model;it considers the new characteristics of COVID19 and is therefore applicable to a population including asymptomatic carriers. The predictive value is enhanced by tuning of the optimal parameters, whose values better reflect the current pandemic. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2022.

The impact of COVID-19 epidemic on the control of important parasitic diseases.

The spread of COVID-19 has increased the risk of contact transmission between people, and imposes challenges and opportunities for the prevention and control of important parasitic diseases. There may be risks of COVID-19 infection during the implementation of the virus control, including in field investigation and intervention, contacting with fecal samples, or with asymptomatic infected people. Therefore, corresponding prevention and control measures should be taken before and during field investigation, and in sample transportation and detection to prevent the risks effectively. In this paper, the risks and corresponding countermeasures in the above processes are discussed in detail, and the opportunities that COVID-19 brought to the disease control system are also analyzed.Copyright © 2021, National Institute of Parasitic Diseases. All rights reserved.

Neurologic presentations of COVID-19: a case series

Introduction: The new pandemic of coronavirus disease 2019 (COVID-19) has evolved certain neurologic syndromes as a presentation of this disease that should be integrated into the whole disease process. Case Presentations: We present cases of neurologic involvement in adult patients with documented bronchopulmonary COVID-19. Certain signs and symptoms are introduced, including new onset seizures, ischemic stroke, and altered mental status in otherwise minimal clinical signs and symptoms of COVID-19. Conclusions: Many neurologic presentations are diagnosed in resolving COVID respiratory infections or in an otherwise asymptomatic individual.

On clinical manifestations of the new coronavirus infection in newborns.

The aim of the research. To study the specifics in manifestations of the new coronavirus infection in newborns. Material and methods. A retrospective analysis of observations of 28 newborns diagnosed with the new coronavirus infection SARS-CoV-2 dated from June to December 2020 was performed. The infants were transferred from the perinatal centre for hospitalisation to the infectious department of a children's hospital. The patients were born to mothers with COVID-19 as well as mothers discharged from hospital and hospitalised later due to COVID-19 acquired through family contact. Clinical and laboratory data of 12 female and 16 male children aged 1 to 28 days were studied. Results. Clinical symptoms of the new coronavirus infection in newborns tend to be different: from asymptomatic course in 46.5 % of the patients to evident pneumonia in 50 % of the children. The newborns admitted with COVID-19 acquired through family contact had more severe disease manifestations. Conclusion. Amidst the pandemic rise of its incidence, the new coronavirus infection COVID-19 is not rare among newborns. COVID-19 newborns did not have a registered severe nosocomial infection, sepsis, multisystem inflammatory syndrome.Copyright © 2022, Krasnoyarsk State Medical University. All rights reserved.

Germline rare variants of lectin pathway genes predispose to asymptomatic SARS-CoV-2 infection in elderly individuals

Background/Objectives: Emerging evidence suggests that complement system infection-dependent hyperactivation may worsen COVID-19 outcome. We investigated the role of predicted high impact variants -referred as Qualifying Variants (QVs) -of complement system genes in predisposing asymptomatic COVID-19 in elderly individuals, known to be more susceptible to severe disease. Method(s): Exploiting Whole-Exome Sequencing (WES) data and 56 complement system genes, we performed a gene-based collapsing test between 164 asymptomatic subjects (age >= 60 y.o.) and 56,885 European individuals from the gnomAD database. We replicated this test comparing the same asymptomatic individuals with 147 hospitalized COVID-19 patients. Result(s): We found an enrichment of QVs in three genes (MASP1, COLEC10 and COLEC11), which belong to the lectin pathway, in the asymptomatic cohort. Moreover, individuals with QVs showed lower serum levels of Masp1 and of prothrombin activity compared to controls while no differences were observed for CH50 and AH50 levels that measure the activity of classical and alternative complement pathways, respectively. Finally, integrative analyses of genome-wide association study and expression quantitative loci traits data showed a correlation between polymorphisms associated with asymptomatic COVID-19 and decreased expression of MASP1, COLEC11 and COLEC10 genes in lung tissue. Conclusion(s): This study suggests that rare genetic variants can protect from severe COVID-19 by mitigating the activation of lectin pathway and prothrombin activity.

Detection of SARS-CoV-2 antibodies among the pre-vaccine population in Bali

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, the cause of coronavirus disease 2019 (COVID-19), has affected millions of people globally. It is a very contagious disease with various clinical manifestations. However, even in asymptomatic patients, it is believed that this virus exposure induces cryptic antibodies as in symptomatic patients. This current study aims to assess the prevalence of SARS-CoV-2 seropositivity by detecting the antibodies specific to the receptor-binding domain (SRBD) of SARS-CoV-2 in the pre-vaccine population in Bali. We assessed specific antibody titers against trimeric spike glycoprotein (S) of SARS-CoV-2 using Roche Elecsys Anti-SARS-CoV-2 S immunoassay in the serum of 510 pre-vaccine subjects without a previous documented history of SARS-CoV-2 infection. The average age was 35.53 years with 56.7% of the subjects being male. Among 510 subjects, 190 (37.3%) subjects were detected to have SARS-CoV-2 SRBD antibody or be seropositive. The range of the antibody titer was zero to 250 U/mL with the average being 44.3 U/mL. The number of subjects who had anti-SARS-Cov-2 SRBD titer above 132 U/mL was 76 (14.9%);it was the minimal antibody titer needed to donate plasma for plasma convalescent therapy. This study revealed a pre-vaccination population, without a history of COVID-19 infection, with seropositivity to SARS-CoV-2, which indicates the underdiagnosis of COVID-19, especially in asymptomatic individuals.

Thematic analysis of national online narratives on regular asymptomatic testing for Covid-19 in schools in England.

OBJECTIVE: To understand the public perceptions of the schools Covid-19 testing programme in England. DESIGN: Qualitative social media analysis. SETTING: Online users of parenting forums (Mumsnet and Netmums), Facebook newspaper pages and Daily Mail online readers, who responded to posts or articles about the schools testing programme in England, between 1 and 31 March, 2021. RESULTS: Overall, seven main themes were identified, these were divided into barriers and facilitators to engaging in testing for Covid-19. Barriers were: uncertainty around testing in the absence of symptoms; concerns about testing; implications about testing positive; mistrust in the Government. Facilitators were: desire to protect others; desire to return to normality; and hearing others' positive experiences. CONCLUSIONS: Our analysis highlighted that alongside well-established barriers to engaging in asymptomatic testing, parents were having to negotiate additional complex decisions around balancing their child's anxiety over testing alongside acknowledgement of the implications of regular testing, such as return to normality and protecting others. Parents and children would benefit from additional practical and social support to facilitate engagement with the schools testing programme.

Asymptomatic but infectious - The silent driver of pathogen transmission. A pragmatic review.

Throughout 2020, COVID-19 interventions prioritised symptomatic individuals despite growing evidence of pre-symptomatic and asymptomatic transmission. From the pandemic we have learned that global health is slow to quantify asymptomatic disease transmission and slow to implement relevant interventions. While asymptomatic infectious periods exist for nearly all pathogens, it is frequently ignored during case finding, and there are limited research efforts to understand its potential to drive small scale outbreaks, epidemics and pandemics. We conducted a pragmatic review on 15 key pathogens including SARS-CoV-2 and Ebola to demonstrate substantial variation in terminology around asymptomatic infectious individuals, and varying proportions of asymptomatic amongst prevalent infectious cases (0-99 %) and their contribution to transmission (0-96 %). While no pattern was discernible by pathogen type (virus, bacteria, parasite) or mode of transmission (direct, indirect or mixed), there are multiple lessons to learn from previous and current control programmes. As found during the COVID-19 pandemic, overlooking asymptomatic infectious individuals can impede disease control. Improving our understanding of how asymptomatic individuals can drive epidemics can strengthen our efforts to control current pathogens, and improve our preparedness for when the next new pathogen emerges..

Sleep disturbance and anxiety symptoms among asymptomatic COVID-19 carriers in Shanghai, China: the mediating role of entrapment and defeat.

BACKGROUND: The COVID-19 pandemic increases the risk of psychological problems, especially for the infected population. Sleep disturbance and feelings of defeat and entrapment are well-documented risk factors of anxiety symptoms. Exploring the psychological mechanism of the development of anxiety symptoms is essential for effective prevention. This study aimed to examine the mediating effects of entrapment and defeat in the association between sleep disturbance and anxiety symptoms among asymptomatic COVID-19 carriers in Shanghai, China. METHODS: A cross-sectional study was conducted from March to April, 2022. Participants were 1,283 asymptomatic COVID-19 carriers enrolled from the Ruijin Jiahe Fangcang Shelter Hospital, Shanghai (59.6% male; mean age = 39.6 years). Questionnaire measures of sleep disturbance, entrapment, defeat, anxiety symptoms, and background characteristics were obtained. A mediation model was constructed to test the mediating effects of entrapment and defeat in the association between sleep disturbance and anxiety symptoms. RESULTS: The prevalence rates of sleep disturbance and anxiety symptoms were 34.3% and 18.8%. Sleep disturbance was positively associated with anxiety symptoms (OR [95%CI] = 5.013 [3.721-6.753]). The relationship between sleep disturbance and anxiety symptoms (total effect: Std. Estimate = 0.509) was partially mediated by entrapment (indirect effect: Std. Estimate = 0.129) and defeat (indirect effect: Std. Estimate = 0.126). The mediating effect of entrapment and defeat accounted for 50.3% of the association between sleep disturbance and anxiety symptoms. CONCLUSION: Sleep disturbance and anxiety symptoms were prevalent among asymptomatic COVID-19 carriers. Entrapment and defeat mediate the association between sleep disturbance and anxiety symptoms. More attention is needed to monitoring sleep conditions and feelings of defeat and entrapment to reduce the risk of anxiety.

Association of epidemiological and clinical features with PCR cycle threshold values of SARS-CoV-2 infection: a cross-sectional study.

The cycle threshold (Ct) in quantitative real-time reverse-transcriptase polymerase chain reaction (qRT-PCR) is inversely correlated to the amount of viral nucleic acid or viral load and can be regarded as an indicator of infectivity. We examined the association of socio-demographic and clinical characteristics of severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) polymerase chain reaction (PCR) positive cases with PCR cycle threshold (Ct) values at the time of diagnosis. SARS-CoV-2 cases reported between 12 October 2020 and 24 January 2021 in Regensburg were analyzed employing bivariate and multivariable methods. We included 3,029 SARS-CoV-2 cases (31% asymptomatic at diagnosis) and analyzed the association of case characteristics with Ct values in 2,606 cases. Among symptomatic patients, cough (38.0%), rhinitis (32.4%), headache (32.0), and fever/chills (29.9%) were the most frequent complaints. Ct values ≤20 were more frequent in symptomatic cases (20.9% vs. 11.3%), whereas Ct values >30 were more common in asymptomatic cases (32.6% vs. 18.0%). Ct values >20 and ≤30 were most common in symptomatic and asymptomatic cases (48.0% vs 40.7%). We observed lower median Ct values of E and N gene in symptomatic cases. In a random forest model, the total number of symptoms, respiratory symptoms, and age were most strongly associated with low Ct values. In conclusion, certain symptoms and age were associated with lower Ct values. Ct values can be used as a pragmatic approach in estimating infectivity at the first notification of a case and, thus, in guiding containment measures.

COVID-19 positive cases among asymptomatic individuals during the second wave in Ndola, Zambia.

Background: Coronavirus disease 2019 (COVID-19) is a worldwide public health concern for healthcare workers. About 80% of cases appear to be asymptomatic, and about 3% may experience hospitalisation and later die. Less than 20% of studies have looked at the positivity rate of asymptomatic individuals. Objective: This study investigated the COVID-19 positivity rates among asymptomatic individuals during the second COVID-19 wave at one of Zambia's largest testing centre. Methods: This was a retrospective cross-sectional study conducted on routine surveillance and laboratory data at the Tropical Diseases Research Centre COVID-19 laboratory in Ndola, Zambia, from 01 December 2020 to 31 March 2021. The study population was made up of persons that had tested for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection as a requirement for travel. Microsoft Excel was used to come up with an epidemiological curve of daily COVID-19 positive cases; proportions for gender were described using frequencies and percentages. Results: A total of 11 144 asymptomatic individuals tested for SARS-CoV-2 were sampled for the study and 1781 (16.0%) returned positive results. The median age among those tested was 36 years (interquartile range: 29-46). Testing for COVID-19 peaked in the month of January 2021 (37.4%) and declined in March 2021 (21.0%). The epidemiological curve showed a combination of continuous and propagated point-source transmission. Conclusion: The positivity rate of 16.0% among asymptomatic individuals was high and could imply continued community transmission, especially during January 2021 and February 2021. We recommend heightened testing for SARS-CoV-2 among asymptomatic individuals. What this study adds: This study adds critical knowledge to the transmission of COVID-19 among asymptomatic travellers who are usually a key population in driving community infection. This knowledge is critical in instituting evidence-based interventions in the screening and management of travellers, and its control.

A COVID-19 Infection Model Considering the Factors of Environmental Vectors and Re-Positives and Its Application to Data Fitting in Japan and Italy.

COVID-19, which broke out globally in 2019, is an infectious disease caused by a novel strain of coronavirus, and its spread is highly contagious and concealed. Environmental vectors play an important role in viral infection and transmission, which brings new difficulties and challenges to disease prevention and control. In this paper, a type of differential equation model is constructed according to the spreading functions and characteristics of exposed individuals and environmental vectors during the virus infection process. In the proposed model, five compartments were considered, namely, susceptible individuals, exposed individuals, infected individuals, recovered individuals, and environmental vectors (contaminated with free virus particles). In particular, the re-positive factor was taken into account (i.e., recovered individuals who have lost sufficient immune protection may still return to the exposed class). With the basic reproduction number R0 of the model, the global stability of the disease-free equilibrium and uniform persistence of the model were completely analyzed. Furthermore, sufficient conditions for the global stability of the endemic equilibrium of the model were also given. Finally, the effective predictability of the model was tested by fitting COVID-19 data from Japan and Italy.

Modified SEIR epidemic model including asymptomatic and hospitalized cases with correct demographic evolution

The aim of this study is to propose a modified Susceptible-Exposed-Infectious-Removed (SEIR) model that describes the time behaviour of symptomatic, asymptomatic and hospitalized patients in an epidemic, taking into account the effect of the demographic evolution. Unlike most of the recent studies where a constant ratio of new individuals is considered, we consider a more correct assumption that the growth ratio is proportional to the total population, following a Logistic law, as is usual in population growth studies for humans and animals. An exhaustive theoretical study is carried out and the basic reproduction number R0 is computed from the model equations. It is proved that if R0<1 then the disease-free manifold is globally asymptotically stable, that is, the epidemics remits. Global and local stability of the equilibrium points is also studied. Numerical simulations are used to show the agreement between numerical results and theoretical properties. The model is fitted to experimental data corresponding to the pandemic evolution of COVID-19 in the Republic of Cuba, showing a proper behaviour of infected cases which let us think that can provide a correct estimation of asymptomatic cases. In conclusion, the model seems to be an adequate tool for the study and control of infectious diseases.

Autoimmune pulmonary alveolar proteinosis in an adolescent girl with rapidly progressive dyspnea

Autoimmune pulmonary alveolar proteinosis (PAP) is a rare disease, especially in pediatrics, but important to consider, as it may avoid unnecessary and/or invasive investigations and delayed diagnosis. This case report highlights an adolescent girl with rapid onset dyspnea but an unremarkable physical exam and initial testing. However, due to a high index of suspicion, a chest computed tomography (CT) scan was done, revealing a "crazy paving" pattern, which then prompted expedited assessment. This finding, however, is not as specific as often discussed and has a broad differential diagnosis, which will be reviewed in detail as part of this case. Furthermore, this report demonstrates a diagnostic approach for PAP that avoids lung biopsy, previously considered to be required for diagnosis of PAP, but is increasingly becoming unnecessary with more advanced blood tests and understanding of their sensitivity and specificity. Additionally, management strategies for PAP will be briefly discussed.Copyright © 2022 Canadian Thoracic Society.