Timing of exposure is critical in a highly sensitive model of SARS-CoV-2 transmission

AbstractTransmission efficiency is a critical factor determining the size of an outbreak of infectious disease. Indeed, the propensity of SARS-CoV-2 to transmit among humans precipitated and continues to sustain the COVID-19 pandemic. Nevertheless, the number of new cases among contacts is highly variable and underlying reasons for wide-ranging transmission outcomes remain unclear. Here, we evaluated viral spread in golden Syrian hamsters to define the impact of temporal and environmental conditions on the efficiency of SARS-CoV-2 transmission through the air. Our data show that exposure periods as brief as one hour are sufficient to support robust transmission. However, the timing after infection is critical for transmission success, with the highest frequency of transmission to contacts occurring at times of peak viral load in the donor animals. Relative humidity and temperature had no detectable impact on transmission when exposures were carried out with optimal timing. However, contrary to expectation, trends observed with sub-optimal exposure timing suggest improved transmission at high relative humidity or high temperature. In sum, among the conditions tested, our data reveal the timing of exposure to be the strongest determinant of SARS-CoV-2 transmission success and implicate viral load as an important driver of transmission.

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Guidelines for accurate genotyping of SARS-CoV-2 using amplicon-based sequencing of clinical samples

10.1101/2020.12.01.405738 ◽

2020 ◽

Author(s):

Slawomir Kubik ◽

Ana Claudia Marques ◽

Xiaobin Xing ◽

Janine Silvery ◽

Claire Bertelli ◽

...

Keyword(s):

Viral Load ◽

Clinical Samples ◽

Sampling Location ◽

Reliable Determination ◽

Viral Genomes ◽

Viral Spread ◽

Broad Applicability ◽

Input Material ◽

Correct Sequence ◽

The Impact

AbstractBackgroundSARS-CoV-2 genotyping has been instrumental to monitor virus evolution and transmission during the pandemic. The reliability of the information extracted from the genotyping efforts depends on a number of aspects, including the quality of the input material, applied technology and potential laboratory-specific biases. These variables must be monitored to ensure genotype reliability. The current lack of guidelines for SARS-CoV-2 genotyping leads to inclusion of error-containing genome sequences in studies of viral spread and evolution.ResultsWe used clinical samples and synthetic viral genomes to evaluate the impact of experimental factors, including viral load and sequencing depth, on correct sequence determination using an amplicon-based approach. We found that at least 1000 viral genomes are necessary to confidently detect variants in the genome at frequencies of 10% or higher. The broad applicability of our recommendations was validated in >200 clinical samples from six independent laboratories. The genotypes of clinical isolates with viral load above the recommended threshold cluster by sampling location and period. Our analysis also supports the rise in frequency of 20A.EU1 and 20A.EU2, two recently reported European strains whose dissemination was favoured by travelling during the summer 2020.ConclusionsWe present much-needed recommendations for reliable determination of SARS-CoV-2 genome sequence and demonstrate their broad applicability in a large cohort of clinical samples.

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Treatment of HIV-associated facial lipoatrophy: impact on infection progression assessed by viral load and CD4 count

Anais Brasileiros de Dermatologia ◽

10.1590/abd1806-4841.2013895 ◽

2013 ◽

Vol 88 (4) ◽

pp. 570-577 ◽

Cited By ~ 5

Author(s):

Flávia Machado Gonçalves Soares ◽

Izelda Maria Carvalho Costa

Keyword(s):

Viral Load ◽

Disease Progression ◽

Statistical Significance ◽

Undetectable Viral Load ◽

Fat Distribution ◽

Cd4 Count ◽

Before And After ◽

Facial Lipoatrophy ◽

A Prospective Study ◽

The Impact

BACKGROUND: HIV/AIDS-Associated Lipodystrophy Syndrome includes changes in body fat distribution, with or without metabolic changes. The loss of fat from the face, called facial lipoatrophy, is one of the most stigmatizing signs of the syndrome.OBJECTIVES:To evaluate the effect of FL treatment using polymethylmethacrylate (PMMA) implants on disease progression, assessed by viral load and CD4 cell count.METHODS: This was a prospective study of 44 patients treated from July 2009 to December 2010. Male and female patients, aged over 18 years, with clinically detectable FL and who had never been treated were included in the study. PMMA implantation was done to fill atrophic areas. Laboratory tests were conducted to measure viral load and CD4 count before and after treatment.RESULTS: Of the 44 patients, 72.72% were male and 27.27% female, mean age of 44.38 years. Before treatment, 82% of patients had undetectable viral load, which increased to 88.6% after treatment, but without statistical significance (p = 0.67). CD4 count before treatment ranged from 209 to 1293, averaging 493.97. After treatment, the average increased to 548.61. The increase in CD4 count after treatment was statistically significant with p = 0.02.CONCLUSION: The treatment of FL with PMMA implants showed a statistically significant increase in CD4 count after treatment, revealing the impact of FL treatment on disease progression. Viral load before and after treatment did not vary significantly.

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Hepatitis B virus (HBV) viral load, liver and renal function in adults treated with tenofovir disoproxil fumarate (TDF) vs. untreated: a retrospective longitudinal UK cohort study

BMC Infectious Diseases ◽

10.1186/s12879-021-06226-0 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Tingyan Wang ◽

David A. Smith ◽

Cori Campbell ◽

Jolynne Mokaya ◽

Oliver Freeman ◽

...

Keyword(s):

Viral Load ◽

Hepatitis B Virus ◽

Hepatitis B ◽

Renal Impairment ◽

Clinical Guidelines ◽

Untreated Group ◽

Liver Inflammation ◽

B Virus ◽

The Impact

Abstract Background Current clinical guidelines recommend treating chronic hepatitis B virus (HBV) infection in a minority of cases, but there are relatively scarce data on evolution or progression of liver inflammation and fibrosis in cases of chronic HBV (CHB) that do not meet treatment criteria. We aimed to assess the impact of TDF on liver disease, and the risk of renal impairment in treated CHB patients in comparison to untreated patients. Methods We studied a longitudinal ethnically diverse CHB cohort in the UK attending out-patient clinics between 2005 and 2018. We examined TDF treatment (vs. untreated) as the main exposure, with HBV DNA viral load (VL), ALT, elastography scores and eGFR as the main outcomes, using paired tests and mixed effects model for longitudinal measurements. Additionally, decline of eGFR during follow-up was quantified within individuals by thresholds based on clinical guidelines. Baseline was defined as treatment initiation for TDF group and the beginning of clinical follow-up for untreated group respectively. Results We included 206 adults (60 on TDF, 146 untreated), with a median ± IQR follow-up duration of 3.3 ± 2.8 years. The TDF group was significantly older (median age 39 vs. 35 years, p = 0.004) and more likely to be male (63% vs. 47%, p = 0.04) compared to the untreated group. Baseline difference between TDF and untreated groups reflected treatment eligibility criteria. As expected, VL and ALT declined significantly over time in TDF-treated patients. Elastography scores normalised during treatment in the TDF group reflecting regression of inflammation and/or fibrosis. However, 6/81 (7.4%) of untreated patients had a progression of fibrosis stage from F0-F1 to F2 or F3. There was no evidence of difference in rates or incidence of renal impairment during follow-up in the TDF vs. untreated group. Conclusions Risk of liver inflammation and fibrosis may be raised in untreated patients compared to those receiving TDF, and TDF may benefit a larger percentage of the CHB population.

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Cost-effectiveness and feasibility of conditional economic incentives and motivational interviewing to improve HIV health outcomes of adolescents living with HIV in Anambra State, Nigeria

BMC Health Services Research ◽

10.1186/s12913-021-06718-4 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Obinna Ikechukwu Ekwunife ◽

Chinelo Janefrances Ofomata ◽

Charles Ebuka Okafor ◽

Maureen Ugonwa Anetoh ◽

Stephen Okorafor Kalu ◽

...

Keyword(s):

Viral Load ◽

Cost Effectiveness ◽

Service Delivery ◽

Motivational Interviewing ◽

Cost Effective ◽

Economic Incentives ◽

Additional Patient ◽

Incentive Scheme ◽

The Cost ◽

The Impact

Abstract Background In sub-Saharan Africa, there is increasing mortality and morbidity of adolescents due to poor linkage, retention in HIV care and adherence to antiretroviral therapy (ART). This is a result of limited adolescent-centred service delivery interventions. This cost-effectiveness and feasibility study were piggybacked on a cluster-randomized trial that assessed the impact of an adolescent-centred service delivery intervention. The service delivery intervention examined the impact of an incentive scheme consisting of conditional economic incentives and motivational interviewing on the health outcomes of adolescents living with HIV in Nigeria. Method A cost-effectiveness analysis from the healthcare provider’s perspective was performed to assess the cost per additional patient achieving undetected viral load through the proposed intervention. The cost-effectiveness of the incentive scheme over routine care was estimated using the incremental cost-effectiveness ratio (ICER), expressed as cost/patient who achieved an undetectable viral load. We performed a univariate sensitivity analysis to examine the effect of key parameters on the ICER. An in-depth interview was conducted on the healthcare personnel in the intervention arm to explore the feasibility of implementing the service delivery intervention in HIV treatment hospitals in Nigeria. Result The ICER of the Incentive Scheme intervention compared to routine care was US$1419 per additional patient with undetectable viral load. Going by the cost-effectiveness threshold of US$1137 per quality-adjusted life-years suggested by Woods et al., 2016, the intervention was not cost-effective. The sensitivity test showed that the intervention will be cost-effective if the frequency of CD4 count and viral load tests are reduced from quarterly to triannually. Healthcare professionals reported that patients’ acceptance of the intervention was very high. Conclusion The conditional economic incentives and motivational interviewing was not cost-effective, but can become cost-effective if the frequency of HIV quality of life indicator tests are performed 1–3 times per annum. Patients’ acceptance of the intervention was very high. However, healthcare professionals believed that sustaining the intervention may be difficult unless factors such as government commitment and healthcare provider diligence are duly addressed. Trial registration This trial is registered in the WHO International Clinical Trials Registry through the WHO International Registry Network (PACTR201806003040425).

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Impact of temperature and relative humidity on the transmission of COVID-19: a modelling study in China and the United States

BMJ Open ◽

10.1136/bmjopen-2020-043863 ◽

2021 ◽

Vol 11 (2) ◽

pp. e043863

Author(s):

Jingyuan Wang ◽

Ke Tang ◽

Kai Feng ◽

Xin Lin ◽

Weifeng Lv ◽

...

Keyword(s):

Regression Analysis ◽

Relative Humidity ◽

Human Mobility ◽

The United States ◽

Reproductive Number ◽

Cross Sectional ◽

The Usa ◽

Higher Temperature ◽

Potential Impact ◽

The Impact

ObjectivesWe aim to assess the impact of temperature and relative humidity on the transmission of COVID-19 across communities after accounting for community-level factors such as demographics, socioeconomic status and human mobility status.DesignA retrospective cross-sectional regression analysis via the Fama-MacBeth procedure is adopted.SettingWe use the data for COVID-19 daily symptom-onset cases for 100 Chinese cities and COVID-19 daily confirmed cases for 1005 US counties.ParticipantsA total of 69 498 cases in China and 740 843 cases in the USA are used for calculating the effective reproductive numbers.Primary outcome measuresRegression analysis of the impact of temperature and relative humidity on the effective reproductive number (R value).ResultsStatistically significant negative correlations are found between temperature/relative humidity and the effective reproductive number (R value) in both China and the USA.ConclusionsHigher temperature and higher relative humidity potentially suppress the transmission of COVID-19. Specifically, an increase in temperature by 1°C is associated with a reduction in the R value of COVID-19 by 0.026 (95% CI (−0.0395 to −0.0125)) in China and by 0.020 (95% CI (−0.0311 to −0.0096)) in the USA; an increase in relative humidity by 1% is associated with a reduction in the R value by 0.0076 (95% CI (−0.0108 to −0.0045)) in China and by 0.0080 (95% CI (−0.0150 to −0.0010)) in the USA. Therefore, the potential impact of temperature/relative humidity on the effective reproductive number alone is not strong enough to stop the pandemic.

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STING and cGAS gene expressions were downregulated among HIV-1-infected persons after antiretroviral therapy

Virology Journal ◽

10.1186/s12985-021-01548-6 ◽

2021 ◽

Vol 18 (1) ◽

Author(s):

Lorena Leticia Peixoto de Lima ◽

Allysson Quintino Tenório de Oliveira ◽

Tuane Carolina Ferreira Moura ◽

Ednelza da Silva Graça Amoras ◽

Sandra Souza Lima ◽

...

Keyword(s):

Gene Expression ◽

Viral Load ◽

T Cell ◽

Antiretroviral Therapy ◽

Cell Count ◽

Enzyme Linked Immunosorbent Assay ◽

Type I ◽

Α Level ◽

The Impact ◽

Hiv 1

Abstract Background The HIV-1 epidemic is still considered a global public health problem, but great advances have been made in fighting it by antiretroviral therapy (ART). ART has a considerable impact on viral replication and host immunity. The production of type I interferon (IFN) is key to the innate immune response to viral infections. The STING and cGAS proteins have proven roles in the antiviral cascade. The present study aimed to evaluate the impact of ART on innate immunity, which was represented by STING and cGAS gene expression and plasma IFN-α level. Methods This cohort study evaluated a group of 33 individuals who were initially naïve to therapy and who were treated at a reference center and reassessed 12 months after starting ART. Gene expression levels and viral load were evaluated by real-time PCR, CD4+ and CD8+ T lymphocyte counts by flow cytometry, and IFN-α level by enzyme-linked immunosorbent assay. Results From before to after ART, the CD4+ T cell count and the CD4+/CD8+ ratio significantly increased (p < 0.0001), the CD8+ T cell count slightly decreased, and viral load decreased to undetectable levels in most of the group (84.85%). The expression of STING and cGAS significantly decreased (p = 0.0034 and p = 0.0001, respectively) after the use of ART, but IFN-α did not (p = 0.1558). Among the markers evaluated, the only markers that showed a correlation with each other were STING and CD4+ T at the time of the first collection. Conclusions ART provided immune recovery and viral suppression to the studied group and indirectly downregulated the STING and cGAS genes. In contrast, ART did not influence IFN-α. The expression of STING and cGAS was not correlated with the plasma level of IFN-α, which suggests that there is another pathway regulating this cytokine in addition to the STING–cGAS pathway.

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Evolution of the viscoelastic properties of painting stratigraphies: a moisture weathering and nanoindentation approach

Heritage Science ◽

10.1186/s40494-021-00552-x ◽

2021 ◽

Vol 9 (1) ◽

Author(s):

Mathilde Tiennot ◽

Davide Iannuzzi ◽

Erma Hermens

Keyword(s):

Mechanical Properties ◽

Relative Humidity ◽

Cultural Heritage ◽

Mechanical Behaviour ◽

Viscoelastic Properties ◽

Viscoelastic Behaviour ◽

Storage And Loss Moduli ◽

Heritage Studies ◽

Paint Films ◽

The Impact

AbstractIn this investigation on the mechanical behaviour of paint films, we use a new ferrule-top nanoindentation protocol developed for cultural heritage studies to examine the impact of repeated relative humidity variations on the viscoelastic behaviour of paint films and their mechanical properties in different paint stratigraphies through the changes in their storage and loss moduli. We show that the moisture weathering impact on the micromechanics varies for each of these pigment-oil systems. Data from the nanoindentation protocol provide new insights into the evolution of the viscoelastic properties dsue to the impact of moisture weathering on paint films.

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Temporal dynamics of viral load and false negative rate influence the levels of testing necessary to combat COVID-19 spread

Scientific Reports ◽

10.1038/s41598-021-88498-9 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Katherine F. Jarvis ◽

Joshua B. Kelley

Keyword(s):

Viral Load ◽

Temporal Dynamics ◽

Reproduction Number ◽

False Negative ◽

False Negative Rate ◽

Agent Based Model ◽

Agent Based ◽

Viral Spread ◽

Negative Rate

AbstractColleges and other organizations are considering testing plans to return to operation as the COVID-19 pandemic continues. Pre-symptomatic spread and high false negative rates for testing may make it difficult to stop viral spread. Here, we develop a stochastic agent-based model of COVID-19 in a university sized population, considering the dynamics of both viral load and false negative rate of tests on the ability of testing to combat viral spread. Reported dynamics of SARS-CoV-2 can lead to an apparent false negative rate from ~ 17 to ~ 48%. Nonuniform distributions of viral load and false negative rate lead to higher requirements for frequency and fraction of population tested in order to bring the apparent Reproduction number (Rt) below 1. Thus, it is important to consider non-uniform dynamics of viral spread and false negative rate in order to model effective testing plans.

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Riding the waves: the ongoing impact of COVID-19 on a national surgical training cohort

Irish Journal of Medical Science (1971 -) ◽

10.1007/s11845-021-02739-4 ◽

2021 ◽

Author(s):

Orla Hennessy ◽

Amy Lee Fowler ◽

Conor Hennessy ◽

David Brinkman ◽

Aisling Hogan ◽

...

Keyword(s):

Surgical Training ◽

World Health Organisation ◽

World Health ◽

Training Methods ◽

Viral Spread ◽

Surgical Services ◽

Global Pandemic ◽

Surgical Trainees ◽

Secondary Survey ◽

The Impact

Abstract Background The World Health Organisation declared a global pandemic on the 11 March 2020 resulting in implementation of methods to contain viral spread, including curtailment of all elective and non-emergent interventions. Many institutions have experienced changes in rostering practices and redeployment of trainees to non-surgical services. Examinations, study days, courses, and conferences have been cancelled. These changes have the potential to significantly impact the education and training of surgical trainees. Aim To investigate the impact of the COVID-19 pandemic on training, educational, and operative experiences of Irish surgical trainees. Methods Surgical trainees were surveyed anonymously regarding changes in working and educational practices since the declaration of the COVID-19 pandemic on 11 March 2020. The survey was circulated in May 2020 to both core and higher RCSI surgical trainees, when restrictions were at level five. Questions included previous and current access to operative sessions as well as operative cases, previous and current educational activities, access to senior-led training, and access to simulation-/practical-based training methods. A repeat survey was carried out in October 2020 when restrictions were at level two. Results Overall, primary and secondary survey response rates were 29% (n = 98/340) and 19.1% (n = 65/340), respectively. At the time of circulation of the second survey, the number of operative sessions attended and cases performed had significantly improved to numbers experienced pre-pandemic (p < 0.0001). Exposure to formal teaching and education sessions returned to pre-COVID levels (p < 0.0001). Initially, 23% of trainees had an examination cancelled; 53% of these trainees have subsequently sat these examinations. Of note 27.7% had courses cancelled, and 97% of these had not been rescheduled. Conclusion Surgical training and education have been significantly impacted in light of COVID-19. This is likely to continue to fluctuate in line with subsequent waves. Significant efforts have to be made to enable trainees to meet educational and operative targets.

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A Qualitative Study of COVID-19 Distress in University Students

Emerging Adulthood ◽

10.1177/21676968211025128 ◽

2021 ◽

pp. 216769682110251

Author(s):

Samantha G. Farris ◽

Mindy M. Kibbey ◽

Erick J. Fedorenko ◽

Angelo M. DiBello

Keyword(s):

University Students ◽

Undergraduate Students ◽

Mental Health Problems ◽

Financial Strain ◽

Public Response ◽

Viral Spread ◽

Future Work ◽

The Impact ◽

Viral Outbreak ◽

Selection Of

The psychological effect of the pandemic and measures taken in response to control viral spread are not yet well understood in university students; in-depth qualitative analysis can provide nuanced information about the young adult distress experience. Undergraduate students ( N = 624) in an early US outbreak “hotspot” completed an online narrative writing about the impact and distress experienced due to the COVID-19 pandemic. Data were collected April-May 2020. A random selection of 50 cases were sampled for thematic analysis. Nine themes were identified: viral outbreak distress, fear of virus contraction/transmission, proximity to virus, dissatisfaction with public response, physical distancing distress, social distancing distress, academic and school-related distress, disruptive changes in health behavior and routines, financial strain and unemployment, worsening of pre-existing mental health problems, and social referencing that minimizes distress. Future work is needed to understand the persistence of the distress, in addition to developing methods for assessment, monitoring, and mitigation of the distress.

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