Cases Of Asymptomatic Infection Research Articles

Severe Panton–Valentine-Leukocidin-Positive Staphylococcus aureus Infections in Pediatric Age: A Case Report and a Literature Review

Background: Infections caused by S. aureus strains encoding Panton–Valentine leukocidin (PVL-SA) have become increasingly relevant in community settings and can cause severe conditions in pediatric populations. We present the pediatric case of an invasive disease caused by PVL-SA and provide a literature review of severe manifestations caused by these strains in children. Methods: A PubMed search (February 2024) found studies that included relevant clinical outcomes, diagnostics, and treatments, excluding cases of asymptomatic infection or in adult populations. A logistical multivariate analysis was used to find predictors of the need for intensive care. Results: A 10-year-old boy came to the attention of our Pediatric Infectious Diseases Unit with fever, chest pain, and tachypnea. A rapid worsening of his clinical conditions was observed, with the development of necrotizing pneumonia, osteomyelitis, deep vein thrombosis (DVT), and multiple abscesses. Blood cultures confirmed the presence of PVL-producing methicillin-resistant S. aureus (MRSA). The initial treatment included linezolid and ceftaroline and was later adjusted to clindamycin, daptomycin, and fosfomycin, with clinical improvement. Discussion: Our review collected 36 articles, including 156 pediatric cases of severe PVL-SA infection. Bacteremia was present in 49% of cases, lung infection in 47%, and osteomyelitis in 37%. The presence of pulmonary localization was predictive of the need for intensive care, O.R. 25.35 (7.46–86.09; p < 0.001). Anti-toxin molecules were used in about half the cases where information on treatment was reported. Our report highlights the capacity of PVL-SA to cause life-threatening complications in children, while also discussing the full range of its clinical spectrum and the most effective therapeutic approaches.

Advanced optimal control approaches for immune boosting and clinical treatment to enhance dengue viremia models using ABC fractional-order analysis.

This work focuses on the Dengue-viremia ABC (Atangana-Baleanu Caputo) fractional-order differential equations, accounting for both symptomatic and asymptomatic infected cases. Symptomatic cases are characterized by higher viremia levels, whereas asymptomatic cases exhibit lower viremia levels. The fractional-order model highlights memory effects and other advantages over traditional models, offering a more comprehensive representation of dengue dynamics. The total population is divided into four compartments: susceptible, asymptomatic infected, symptomatic infected, and recovered. The model incorporates an immune-boosting factor for asymptomatic infected individuals and clinical treatment for symptomatic cases. Positivity and boundedness of the model are validated, and both local and global stability analyses are performed. The novel Adams-Bash numerical scheme is utilized for simulations to rigorously assess the impact of optimal control interventions. The results demonstrate the effectiveness of the proposed control strategies. The reproduction numbers must be reduced based on specific optimal control conditions to effectively mitigate disease outbreaks. Numerical simulations confirm that the optimal control measures can significantly reduce the spread of the disease. This research advances the understanding of Dengue-viremia dynamics and provides valuable insights into the application of ABC fractional-order analysis. By incorporating immune-boosting and clinical treatment into the model, the study offers practical guidelines for implementing successful disease control strategies. The findings highlight the potential of using optimal control techniques in public health interventions to manage disease outbreaks more effectively.

Adherence of Mild and Asymptomatic Covid-19 Positive Patients to Ain Shams University Home Isolation Protocol

Abstract Background Egypt has reported almost 515,103 confirmed cases of coronavirus disease (COVID-19) with 24,779 deaths from January 3rd, 2020 to May 29th, 2022. To date, the clinical picture of coronavirus infection among Egyptian patients has not been well-characterized. Asymptomatic infection and mild cases make up a large proportion of infections all over the world. According to Ain Shams University guidelines, asymptomatic and mild cases can be isolated at home; however it is unclear to what extent patients adhere to home isolation guidelines, and whether home isolation was in fact effective in reducing infection among the patient’s family contacts. Aim of the Work The aim of this study was: Describe the socio-demographic characteristics of asymptomatic and mild patients eligible for home isolation and measure the adherence of patients isolated at home to the recommended control measures with telemedicine follow up. Patients and Methods This is a retrospective cohort study conducted in Ain Shams University on 400 patients who were diagnosed as positive for covid-19, classified as asymptomatic or mild cases at presentation and recommended for home isolation. Results In our cohort, Patients that were adherent to home isolation guidelines had similar household infection rate to those with less compliance except for those who had more than one bathroom, household infection had significant negative correlation to number of bathrooms (p = 0.003) because the patient was able to have personal bathrooms. Regarding family members, 57.8% of cases had members with no symptoms of COVID-19 and 43.2 % had members with symptoms or positive test. Conclusion Our study was limited with the low number of patients from a single centre. However, our findings showed that self-isolation at home may be an alternative to manage mild cases or asymptomatic patients when applied with careful and close observation.

Impact of COVID-19 and Vaccination During Pregnancy on Placenta-Mediated Complications (COVIGRO Study)

ObjectivesCOVID-19 has been associated with preterm birth (PTB) and placental-mediated complications, including fetal growth restriction and preeclampsia (PE). This study aimed to estimate the impact of COVID-19 and vaccination on adverse pregnancy outcomes and markers of placental function. MethodsWe performed a study on a prospective cohort of women recruited in the first trimester of pregnancy during the early COVID-19 pandemic period (December 2020 to December 2021). At each trimester of pregnancy, the assessment included a questionnaire on COVID-19 and vaccination status; serological tests for COVID-19 (for asymptomatic infection); measurement of placental growth factor (PlGF) and soluble fms-like tyrosine kinase 1 (sFlt-1) in maternal blood; measurement of mean uterine artery pulsatility index (UtA-PI); and pregnancy outcomes (PTB, PE, birth weight below the fifth and the tenth percentile). ResultsAmong 788 patients with complete data, we observed 101 (13%) cases of symptomatic infection and 74 (9%) cases of asymptomatic infection with SARS-CoV-2. Most cases (73%) of infection were among women with previous vaccination or COVID-19 infection before pregnancy. COVID-19 infection was not associated with adverse pregnancy outcomes, abnormal fetal growth, sFlt-1/PlGF ratio, or mean UtA-PI. Vaccination during pregnancy did not influence these outcomes either. We observed no case of severe COVID-19 infection requiring respiratory support. ConclusionMild symptomatic or asymptomatic COVID-19 during pregnancy did not influence the risk of adverse pregnancy outcomes and the markers of placental function in predominantly vaccinated women. Fetal growth monitoring is unlikely to be mandatory in women with mild symptoms of COVID-19.

Investigating the Spatiotemporal Relationship between the Built Environment and COVID-19 Transmission

Earlier studies have examined various factors that may contribute to the contagion rate of COVID-19, such as urban climatic and socioeconomic characteristics. However, there is a lack of studies at the township level detailing the spatiotemporal settings of built environment attributes, especially in the context of lockdown as a response to the global Omicron outbreak. In this study, we extended the existing literature by relating the initial-stage Omicron pandemic conditions with more comprehensive measures of the built environment, including density, diversity, design, distance to transit, and destination accessibility. The variations from the confirmed clusters of COVID-19 and asymptomatic infected cases before, during, and after the lockdown throughout the Omicron outbreak were identified geographically using GIS methods in 218 township-level divisions across Shanghai during the lockdown period. We also compared the regression results of the ordinary least-squares regression, geographically weighted regression, and geographically and temporally weighted regression. Our results show that (1) among all the built environment variables, metro line length, walking accessibility, hotel and inn density, and population exhibited positive significance in influencing pandemic prevalence; (2) spatial and temporal variations were evident in the association between accessibility, mobility, density-related built environment variables, and COVID-19 transmission across three phases: pre-lockdown, during lockdown, and post-lockdown. This study highlights the importance of targeted public health interventions in densely populated areas with high demand for public transit. It emphasizes the significance of transportation network layout and walking accessibility in controlling the spread of infectious diseases in specific urban contexts. By considering these factors, policymakers and stakeholders can foster urban resilience and effectively mitigate the impact of outbreaks, aligning with the objectives of the 2030 UN Sustainable Development Goals.

Clinical features of 23 neonates infected with Omicron variant of severe acute respiratory syndrome coronavirus 2

To summarize the clinical features of neonates infected with Omicron variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The medical data of 23 neonates with Omicron variant of SARS-CoV-2 infection admitted to the City North Campus of Urumqi First People's Hospital from October to December 2022 were retrospectively reviewed. All 23 infants had a history of exposure to confirmed caregivers with SARS-CoV-2 infection after birth, and none of them was vertically transmitted. Clinical classification: 5 cases of asymptomatic infection, 18 cases of mild infection, and no cases of moderate, severe, or critically ill. The first symptoms were fever in 13 cases, cough in 3 cases, nasal congestion in 1 case, and diarrhea in 1 case. Blood white blood cell counts decreased in 2 cases, and C-reactive protein increased in 1 case. Seven infants underwent chest X-ray examination due to cough or shortness of breath, and one of which showed focal exudative changes, while the rest showed no abnormal changes. All infants were discharged after symptomatic treatment and the median hospital stay was 6 days. The duration of nucleic acid positivity of SARS-CoV-2 was negatively correlated with N gene Ct values and ORF1ab gene Ct values (rs=-0.719 and -0.699, respectively; P<0.05). One month after discharge, all infants had no symptoms or signs of nucleic acid re-positivity. The clinical manifestations are usually mild or asymptomatic in neonates infected with SARS-CoV-2 Omicron variant. The lower the Ct values of the N and ORF1ab genes of SARS-CoV-2, the longer the duration of nucleic acid positivity. Neonates infected with SARS-CoV-2 Omicron variant can have a good prognosis after symptomatic treatment.

Limitation of Interpreting a Single COVID Cycle Threshold Value

Abstract The United States reported its first case of coronavirus disease 2019 (COVID-19) in January 2020. There was limited testing capacity at the time, and the causative agent severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was indeed extremely infectious. Testing, therefore, has become a vital part of controlling the COVID-19 pandemic. Nucleic acid amplification tests, such as polymerase chain reaction platform, a value called cycle threshold (Ct) is reported. This number represents the number of polymerase chain reaction test cycles it takes for the sample to become positive. It is inversely proportional to the amount of viral RNA present in the sample. Therefore, a high Ct value infers a low quantity of viral RNA, and conversely, a low Ct value implies high viral RNA, which in turn correlates with infectivity. When interpreted appropriately with the right clinical context, it could be used to assess the infectiousness of an individual. In September 2021, a 73-year-old man who previously completed a primary series of Moderna vaccine (2 injections) presented to the hospital with chest pain. Cardiac catheterization showed multivessel coronary artery disease and was deemed to have unstable angina. The plan was to undergo coronary aortic bypass graft surgery. Preoperative routine testing revealed a positive COVID-19 polymerase chain reaction test with a high Ct value. During the hospital stay, it was shown that he had a decreased Ct value and thus was determined to have an acute case of asymptomatic COVID-19 infection. His surgery was delayed according to the isolation protocol per Centers for Disease Control and Prevention for safety precautions. He eventually underwent coronary aortic bypass graft after completion of isolation and had an uneventful postoperative course. It was also documented that he had serological seroconversion consistent with acute COVID-19 infection. This case illustrates that reporting Ct values is useful in a certain clinical context, but clinicians need to be familiar with the transmissibility and history of SARS-CoV-2 infection as well as understanding the interpretation of positive tests. The appropriate clinical approach and management should be assessed based on exposure history, epidemiology, physical examination, radiographic assessment, and laboratory studies.

Late-onset and congenital hearing loss detected using AABR due to congenital cytomegalovirus infection that improved with valganciclovir.

Congenital cytomegalovirus (cCMV) infection is the most common congenital viral infection and is the leading non-genetic cause of sensorineural hearing loss and an important cause of neurodevelopmental disabilities. Auto auditory brainstem response (AABR) is a simple hearing test and used for the purpose of neonatal hearing screening, but can use it for early detection hard of hearing within the study age of the model. We experienced two case of asymptomatic CMV infection in which congenital and late-onset hearing loss were diagnosed early with AABR, and hearing loss improved with valganciclovir.

Quantitative evaluation of the role of Fangcang shelter hospitals in the control of Omicron transmission: A case study of the outbreak in Shanghai, China in 2022

Since Omicron began to spread in China, Shanghai has become one of the cities with more severe outbreaks. Under the comprehensive consideration of the vaccine coverage rate, the number of Fangcang shelter hospital beds and the number of designated hospital beds in Shanghai, this paper established a deterministic compartmental model and used the Nelder-Mead Simplex Direct Search Algorithm and chi-square values to estimate the model parameters. we calculate ℛ0 = 3.6429 when the number of beds in the Fangcang shelter hospital is relatively tight in the second stage and ℛ0 = 0.4974 in the fifth stage when there are enough beds in both Fangcang shelter hospital and designated hospital. Then we perform a sensitivity analysis on ℛ0 by using perturbation of fixed point estimation of model parameters in the fifth stage, and obtain three parameters that are more sensitive to ℛ0, which are transmission rate (β1d), proportion of the infectious (η) and the hospitalization rate of asymptomatic infected cases (δ1). Through simulation, we obtain that if the hospitalization rate of asymptomatic infections δ2 > 0.9373 or the transmission rate β1b < 0.0467, the second stage of Omicron transmission in Shanghai can be well controlled. Finally, we find the measure that converting the National Convention and Exhibition Center (NECC) into a Fangcang shelter hospital has played an important role in curbing the epidemic. Whether this temporary Fangcang shelter hospital is not built or delayed, the cumulative number of confirmed cases will both exceed 100,000, and the cumulative asymptomatic infections will both exceed 1 million. In addition, for a city of 10 million people, we obtain that if a permanent Fangcang shelter hospital with 17,784 beds is built ahead of epidemic, there will be no shortage of beds during the outbreak of Omicron. Our findings enrich the content of the impact of Fangcang shelter hospital beds on the spread of Omicron and confirm the correct policy adopted by the Chinese government.

Using time-dependent reproduction number to predict turning points of COVID-19 outbreak in Dalian, Liaoning province, China.

To forecast the development trend of current outbreak in Dalian, mainly to predict turning points of COVID-19 outbreak in Dalian, Liaoning province, China, the results can be used to provide a scientific reference for timely adjustment of prevention and control strategies. During the outbreak, Bayesian framework was used to calculated the time-dependent reproduction number ([Formula: see text]), and then above acquired [Formula: see text] and exponential trend equation were used to establish the prediction model, through the model, predict the [Formula: see text] value of following data and know when [Formula: see text] smaller than 1. From July 22 to August 5, 2020, and from March 14 to April 2, 2022, 92 and 632 confirmed cases and asymptomatic infected cases of COVID-19 were reported (324 males and 400 females) in Dalian. The R square for exponential trend equation were 0.982 and 0.980, respectively which fit the [Formula: see text] with illness onset between July 19 to July 28, 2020 and between March 5 to March 17, 2022. According to the result of prediction, under the current strength of prevention and control, the [Formula: see text] of COVID-19 will drop below 1 till August 2, 2020 and March 26, 2022, respectively in Dalian, one day earlier or later than the actual date. That is, the turning point of the COVID-19 outbreak in Dalian, Liaoning province, China will occur on August 2, 2020 and March 26, 2022. Using time-dependent reproduction number values to predict turning points of COVID-19 outbreak in Dalian, Liaoning province, China was effective and reliable on the whole, and the results can be used to establish a sensitive early warning mechanism to guide the timely adjustment of COVID-19 prevention and control strategies.

Non-falciparum species and submicroscopic infections in three epidemiological malaria facets in Cameroon

BackgroundThere are growing reports on the prevalence of non-falciparum species and submicroscopic infections in sub-Saharan African countries but little information is available from Cameroon.MethodsA hospital-based cross-sectional study was carried out in four towns (Douala, Maroua, Mayo-Oulo, and Pette) from three malaria epidemiological strata (Forest, Sahelian, and Soudanian) of Cameroon. Malaria parasites were detected by Giemsa light microscopy and polymerase chain reaction (PCR) assay. Non-falciparum isolates were characterized and their 18S gene sequences were BLASTed for confirmatory diagnosis.ResultsPCR assay detected malaria parasites in 82.4% (98/119) patients, among them 12.2% (12/98) were asymptomatic cases. Three Plasmodium species viz. P.falciparum, P.ovalecurtisi and P.vivax, and two co-infection types (P.falciparum + P.vivax and P.falciparum + P.ovalecurtisi) were found. The remaining infections were mono–infections with either P.falciparum or P.ovalecurtisi. All non–falciparum infections were symptomatic and microscopic. The overall proportion of submicroscopic infections was 11.8% (14/119). Most asymptomatic and submicroscopic infection cases were self-medicated with antimalarial drugs and/or medicinal plants. On analysis, P.ovalecurtisi sequences were found to be phylogenetically closer to sequences from India while P.vivax isolates appeared closer to those from Nigeria, India, and Cameroon. No G6PD-d case was found among non-falciparum infections.ConclusionsThis study confirms our previous work on circulation of P.vivax and P.ovalecurtisi and the absence of P.knowlesi in Cameroon. More studies are needed to address non-falciparum malaria along with submicroscopic infections for effective malaria management and control in Cameroon.

Distinct gut microbiota and health outcomes in asymptomatic infection, viral nucleic acid test re-positive, and convalescent COVID-19 cases.

Gut microbiota composition is suggested to associate with coronavirus disease 2019 (COVID‐19) severity, but the impact of gut microbiota on health outcomes is largely unclear. We recruited 81 individuals from Wuhan, China, including 13 asymptomatic infection cases (Group A), 24 COVID‐19 convalescents with adverse outcomes (Group C), 31 severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) re‐positive cases (Group D), and 13 non‐COVID‐19 healthy controls (Group H). The microbial features of Groups A and D were similar and exhibited higher gut microbial diversity and more abundant short‐chain fatty acid (SCFA)‐producing species than Group C. Group C was enriched with opportunistic pathogens and virulence factors related to adhesion and toxin production. The abundance of SCFA‐producing species was negatively correlated, while Escherichia coli was positively correlated with adverse outcomes. All three groups (A, C, and D) were enriched with the mucus‐degrading species Akkermansia muciniphila, but decreased with Bacteroides‐encoded carbohydrate‐active enzymes. The pathways of vitamin B6 metabolic and folate biosynthesis were decreased, while selenocompound metabolism was increased in the three groups. Specifically, the secondary bile acid (BA) metabolic pathway was enriched in Group A. Antibiotic resistance genes were common among the three groups. Conclusively, the gut microbiota was related to the health outcomes of COVID‐19. Dietary supplementations (SCFAs, BA, selenium, folate, vitamin B6) may be beneficial to COVID‐19 patients.

Evaluation of different types of face masks to limit the spread of SARS-CoV-2: a modeling study

We expanded a published mathematical model of SARS-CoV-2 transmission with complex, age-structured transmission and with laboratory-derived source and wearer protection efficacy estimates for a variety of face masks to estimate their impact on COVID-19 incidence and related mortality in the United States. The model was also improved to allow realistic age-structured transmission with a pre-specified R0 of transmission, and to include more compartments and parameters, e.g. for groups such as detected and undetected asymptomatic infectious cases who mask up at different rates. When masks are used at typically-observed population rates of 80% for those ≥ 65 years and 60% for those < 65 years, face masks are associated with 69% (cloth) to 78% (medical procedure mask) reductions in cumulative COVID-19 infections and 82% (cloth) to 87% (medical procedure mask) reductions in related deaths over a 6-month timeline in the model, assuming a basic reproductive number of 2.5. If cloth or medical procedure masks’ source control and wearer protection efficacies are boosted about 30% each to 84% and 60% by cloth over medical procedure masking, fitters, or braces, the COVID-19 basic reproductive number of 2.5 could be reduced to an effective reproductive number ≤ 1.0, and from 6.0 to 2.3 for a variant of concern similar to delta (B.1.617.2). For variants of concern similar to omicron (B.1.1.529) or the sub-lineage BA.2, modeled reductions in effective reproduction number due to similar high quality, high prevalence mask wearing is more modest (to 3.9 and 5.0 from an R0 = 10.0 and 13.0, respectively). None-the-less, the ratio of incident risk for masked vs. non-masked populations still shows a benefit of wearing masks even with the higher R0 variants.

How and to what extent does the anti-social behavior of violating self-quarantine measures increase the spread of disease?

COVID-19 has shown that quarantine (or self-isolation) may be the only available tool against an unknown infectious disease if neither an effective vaccine nor anti-viral medication is available. Motivated by the fact that a considerable number of people were not compliant with the request for self-quarantine made by public authorities, this study used a multi-agent simulation model, whose results were validated by theory work, which highlights how and to what extent such an anti-social behavior hampers the confinement of a disease. Our framework quantifies two important scenarios: in one scenario a certain number of individuals totally ignore quarantine, whereas in the second scenario a larger number of individuals partially ignore the imposed policy. Our results reveal that the latter scenario can be more hazardous even if the total amount of social deficit of activity—measured by the total number of severed links in a physical network—would be same as the former scenario has, of which quantitative extent is dependent on the fraction of asymptomatic infected cases and the level of quarantine intensity the government imposing. Our findings have significance not only to epidemiology but also to research in the broader field of network science. PACS numbersTheory and modeling; computer simulation, 87.15.Aa; Dynamics of evolution, 87.23.Kg.

Analysis of prescription and medication rules of traditional Chinese medicine in the treatment of the coronavirus disease 2019 based on traditional Chinese medicine inheritance support platform

To analyze the rules of medication and principles of formulas for the treatment of coronavirus disease 2019 (COVID-19) using the traditional Chinese medicine inheritance support platform (V2.5). The clinical data, including gender, age, clinical symptoms, frequency of traditional Chinese medicine medication and prescription information, of patients with COVID-19 and asymptomatic infection who were admitted to Hebei COVID-19 designated hospital supported by medical team of First Affiliated Hospital of Hebei University of Chinese Medicine from January to March 2021 were collected. The information data were input into the traditional Chinese medicine inheritance support platform (V2.5). The data mining and analysis were realized by the integrated association rules and complex entropy clustering analysis methods of the software, including the analysis of the frequency of each drug use, drug meridian, taste, and prescription rules, and the new prescriptions were developed. A total of 564 patients (564 prescriptions) were enrolled, involving 200 Chinese herbs, including 357 cases of common COVID-19 and 207 cases of asymptomatic infection. The proportion of women with common COVID-19 was high, and the high incidence age group was 51-70 years old. There was no significant difference in gender of asymptomatic infection, and the high incidence age group was 1-20 years old. The main clinical manifestations of most patients were head heavy and cough, followed by low fever and cough with sputum, the main tongue coating and pulse pattern were similar in both types of patients. The frequency of traditional Chinese medicine used in patients with common type of COVID-19 from high to low was liquorice root (326 times), indian bread (264 times), pinellia tuber (263 times), bitter apricot seed (236 times), baical skullcap root (229 times), gypsum (205 times), agastache rugosus (201 times), dried tangerine peel (194 times), ephedra (184 times), and Chinese thorowax root (163 times), while that used by asymptomatic infection were baical skullcap root (174 times), liquorice root (142 times), medicated leaven (137 times), agastache rugosus (127 times), pinellia tuber (114 times), Chinese thorowax root (100 times), officinal magnolia bark (91 times), atractylodes rhizome (89 times), peony root (84 times), and milkvetch root (83 times). The two types of patients were mainly treated with warm, cold and flat drugs, and the nature and taste were mainly pungent, bitter and sweet. The meridian tropism of drugs was mainly lung, spleen and stomach. High frequency drug formulation mainly included drugs for resolving turbidity and detoxification. At the same time, seven new prescriptions for common COVID-19 and four new prescriptions for asymptomatic infection were developed. The primary reason for the COVID-19 occurrence and development is turbidity-toxin and the qi of plague, and resolving turbidity and detoxication are the basic treating principle. On the basis, for patients with common COVID-19, symptomatic treatment such as relieving exterior syndrome, clearing heat, resolving phlegm, and antitussive drugs should be taken into account at the same time, while the treatment of asymptomatic infections should focus more on supporting the body and eliminating the harmful pathogens.

Epidemiological study and health management of an imported incident of COVID–19 asymptomatic cases in Haikou, China

Background: To control the imported risks brought by all international arrivals, China Customs has implemented strict closed-loop health management policy called “three checks, three screenings and one transfer”. This study provides epidemiological evidence for prevention and control measures on imported cases of asymptomatic infections and describes the current COVID-19 prevention and control system on imported risks in China. Methods: We retrospectively analyzed an imported incident of three asymptomatic carriers. Serum SARS-CoV-2 IgM and IgG antibodies were detected by chemiluminescence and gold immnnochromatography(GICA). Results: Three cases were reported positive for SARS-CoV-2 nucleic acid on their arrival, total antibodies and IgG, but negative for IgM. The Ct values of cases A, B and C were 34/36/36, 32/33/32 and 25/31/29, respectively. There were 10726434 pair-end reads sequenced for case C, and approximate 80% reads were aligned to the hCoV-19/Wuhan/IVDC-HB-01/2019 genome (EPI_ISL_402119). The viruses of case A and C were homologous and came from the SARS-CoV-2 variant. Conclusion: Serum antibody IgM and IgG tests are recommended for international travelers from epidemic areas. The “three checks, three screenings and one transfer” policy implemented at custom's entry points was effective in COVID-19 prevention and control.

Approximating the asymptomatic infectious cases of the COVID-19 disease in Algeria and India using a mathematical model

In this research, we are interested in discussing the evolution of the COVID-19 infection cases and predicting the spread of COVID-19 disease in Algeria and India. To this aim, we will approximate the transmission rate in terms of the measures taken by the governments. The least square method is used with an accuracy of 95% for fitting the artificial solution with the real data declared by WHO for the purpose of approximating the density of asymptomatic individuals for COVID-19 disease. As a result, we obtained the different values of the basic reproduction number (BRN) corresponding to each measure taken by the governments. Moreover, we estimate the number of asymptomatic infected persons at the epidemic peak for each country. Further, we will determine the needed ICU beds (intense medical carte beds) and regular treatment beds. Also, we provide the outcome of governmental strategies in reducing the spread of disease. Combining all these components, we offer some suggestions about the necessity of using the recently discovered vaccines as Pfizer/Bioentec and Moderna for limiting the spread of the COVID-19 disease in the studied countries.

Single-Cell Immunogenomic Approach Identified SARS-CoV-2 Protective Immune Signatures in Asymptomatic Direct Contacts of COVID-19 Cases.

The response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is largely impacted by the level of virus exposure and status of the host immunity. The nature of protection shown by direct asymptomatic contacts of coronavirus disease 2019 (COVID-19)-positive patients is quite intriguing. In this study, we have characterized the antibody titer, SARS-CoV-2 surrogate virus neutralization, cytokine levels, single-cell T-cell receptor (TCR), and B-cell receptor (BCR) profiling in asymptomatic direct contacts, infected cases, and controls. We observed significant increase in antibodies with neutralizing amplitude in asymptomatic contacts along with cytokines such as Eotaxin, granulocyte-colony stimulating factor (G-CSF), interleukin 7 (IL-7), migration inhibitory factor (MIF), and macrophage inflammatory protein-1α (MIP-1α). Upon single-cell RNA (scRNA) sequencing, we explored the dynamics of the adaptive immune response in few representative asymptomatic close contacts and COVID-19-infected patients. We reported direct asymptomatic contacts to have decreased CD4+ naive T cells with concomitant increase in CD4+ memory and CD8+ Temra cells along with expanded clonotypes compared to infected patients. Noticeable proportions of class switched memory B cells were also observed in them. Overall, these findings gave an insight into the nature of protection in asymptomatic contacts.

Diversity of Rotavirus Strains in Children; Results From a Community-Based Study in Nepal.

Objective: The objectives of this study were to describe the incidence and genetic diversity of Rotavirus (RV) infection among children up to 3 years of age in a community in Nepal.Methods: We investigated community-acquired cases of asymptomatic and symptomatic RV infections in children from birth to 36 months of age in a community-based birth cohort in Bhaktapur, Nepal. Monthly surveillance and diarrheal stool samples were collected from 240 children enrolled at birth, of which 238 completed the 3 years of follow-up. Samples were screened for rotavirus by Enzyme Immuno Assay (EIA). All RV screened positives were further genotyped by reverse transcription-polymerase chain reaction for the capsid genes VP7 and VP4.Results: In total, 5,224 stool samples were collected from 238 children, followed from birth to 36 months of age. Diarrhea occurred in 92.4% (230/238) of all children in the cohort. During the 3 years study period, RV was more frequently seen in children with symptoms (7.6%) than in non-symptomatic children (0.8%). The highest RV detection rate was found in younger children between 3 and 21 months of age. Although rotavirus is known as winter diarrhea, it was detected throughout the year except in August. The highest positivity rate was observed in the months between December and March, with a peak in January. Four common G types were seen: G2 (30%), G1 (29%), G12 (19%), and G9 (16%). The most predominant genotypes seen were G2P[4] (30%), followed by G1P[8] (27.0%), G12P[6] (14.0%), G9P[8] (10%), and remaining were mixed, partial, and untyped.Conclusion: Our study confirms that rotavirus is a common cause of gastroenteritis in young children in the community. The prevalence and pathogenicity of rotavirus infection differed by age. There was substantial variability in circulating strains in the community samples compared to samples collected from hospitals. This shows the importance of including community-based surveillance systems to monitor the diversity of circulating rotavirus strains in Nepal.

New problems and countermeasures in the prevention and control of COVID-19

New problems and countermeasures in the prevention and control of COVID-19