Actus Santé

Survey of Direct and Indirect Effects of COVID-19 on Eyes and the Common Ocular Manifestations

Purpose: Ocular manifestations were reported in many recent observations that studied either the effect of COVID-19 directly on eyes or of face mask use. Hence, this study aimed to investigate the effect of COVID-19 on the eyes and make a clear comparison of its direct and indirect effect from face mask-wearing. Methods: This was a cross-sectional study of both written and web-based questionnaires, distributed among a group of COVID-19 patients and a matched control group, the questionnaire consisted of common demographic data, COVID-19 infection history and its symptoms, focusing on ocular symptoms and the presence of conditions related to or cause eye symptoms. As well as the use of face masks that were assessed in terms of the complained ocular manifestation Results: Of 618 participants, 252 had COVID-19 and 366 never had COVID-19. Ocular manifestation among COVID-19 incidence was 44%, significantly higher than non-infected participants' incidence (35.8%), adjusted odds ratio, 95% confidence interval (AOR, 95%CI); 1.45 (1.02-2.06)). Eye discharges (p-value = 0.033) and photosensitivity (p-value = 0.003) were noted more commonly among COVID-19 participants compared to healthy control. When comparing long periods of face mask use with each ocular symptom; dry eye based on OSDI, forging body sensation, eye pain and eye discharges, were found significantly common among extended periods of face mask use.
Catégories: Actus Santé

Modeling remdesivir antiviral efficacy in COVID-19 hospitalized patients of the randomized, controlled, open-label DisCoVeRy trial

Despite several clinical studies, the antiviral efficacy of remdesivir in COVID-19 hospitalized patients remains controversial. We analyzed nasopharyngeal normalized viral loads collected in the 29 days following randomization from 665 hospitalized patients included in the DisCoVeRy trial, allocated to either standard of care (SoC, N=329) or SoC + remdesivir for 10 days (N=336). We used a mathematical model to reconstruct viral kinetic profiles and estimate the antiviral efficacy of remdesivir in reducing viral production. To identify factors associated with viral kinetics, additional analyses were conducted stratified either on time of treatment initiation ([≤] or > 7 days since symptom onset) or viral load at randomization (< or [≥] 3.5 log10 copies/104 cells). In our model, remdesivir reduced viral production by 2-fold on average (95%CI: 1.5-3.2). Using the estimated parameter of the model, simulations predict that remdesivir reduces time to viral clearance by 0.7 day compared to SoC, with large inter-individual variabilities (Inter-Quartile Range, IQR: 0.0-1.3 days). Exploratory analyses suggest that remdesivir had a larger impact in patients with a high viral load at randomization, reducing viral production by 5-fold on average (95%CI: 2.8-25), leading to a predicted median reduction in the time to viral clearance of 2.4 days (IQR: 0.9-4.5 days). In summary, our model shows that remdesivir reduces viral production from infected cells by a factor 2, leading to a median reduction of 0.7 days in the time to viral clearance compared to SoC. The efficacy was larger in patients with high level of viral load at treatment initiation.
Catégories: Actus Santé

Monoclonal Antibody Treatment of Breakthrough COVID-19 in Fully Vaccinated Individuals with High-Risk Comorbidities

Abstract Breakthrough COVID-19 may occur in fully vaccinated persons. In this cohort of 1395 persons (mean age, 54.3 years; 60% female; median body mass index, 30.7) who developed breakthrough COVID-19, there were 107 (7.7%) who required hospitalization by day 28. Hospitalization was significantly associated with the number of medical comorbidities. Anti-spike monoclonal antibody treatment was significantly associated with a lower risk of hospitalization (Odds Ratio: 0.227; 95% confidence interval, 0.128 - 0.403; p<0.001). The number needed to treat to prevent one hospitalization was 225 among the lowest-risk patient group compared to 4 among the groups with highest numbers of medical comorbidity.
Catégories: Actus Santé

Transmission and Unvaccinated-Only Testing in Populations of Mixed Vaccination Status

In populations with mixed vaccination status, testing programs focused on the unvaccinated have been proposed and enacted to mitigate the spread of SARS-CoV-2. While the benefits of universal SARS-CoV-2 screening are well established, it is unclear how the benefits of unvaccinated-only testing depend on population vaccination rate. Here, we introduce and analyze a model of SARS-CoV-2 transmission in which a variable fraction of the population is fully vaccinated and those who remain unvaccinated are proactively tested for infection, while varying transmission rates, vaccine performance parameters, and the degree of social mixing between vaccinated and unvaccinated populations. We find that unvaccinated testing programs are effective only when compliance is high and testing is frequent, and when vaccine coverage is low or moderate. However, in highly vaccinated populations, the impact of testing unvaccinated individuals decreases, and, by analyzing the possible modes of transmission within and between the unvaccinated and vaccinated populations, we show that the unvaccinated community ceases to be the dominant driver of transmission. By evaluating a wide range of scenarios, this work focuses on elucidating general principles, finding broadly that resources devoted to routine testing of the unvaccinated population could be reallocated to other needs when vaccine coverage is sufficiently high.
Catégories: Actus Santé

Wastewater-Based Epidemiological Modeling for Continuous Surveillance of COVID-19 Outbreak

Using wastewater surveillance as a continuous pooled sampling technique has been in place in many countries since the early stages of the outbreak of COVID-19. Since the beginning of the outbreak, many research works have emerged, studying different aspects of viral SARS-CoV-2 DNA concentrations (viral load) in wastewater and its potential as an early warning method. However, one of the questions that has remained unanswered is the quantitative relation between viral load and clinical indicators such as daily cases, deaths, and hospitalizations. Few studies have tried to couple viral load data with an epidemiological model to relate the number of infections in the community to the viral burden. This paper proposes a stochastic wastewater-based SEIR model to showcase the importance of viral load in the early detection and prediction of an outbreak in a community. We built three models based on whether or not they use the case count and viral load data and compared their simulations and forecasting quality. Our results demonstrate that a simple SEIR model based on viral load data can reliably predict the number of infections in the future. Therefore, wastewater-based surveillance is a promising way of monitoring the spread of COVID-19 and can provide city officials with timely information about the circulation of COVID-19 in the community.
Catégories: Actus Santé

Response to Tozinameran (BNT162b2) booster in twice-vaccinated kidney transplant and maintenance dialysis patients

Background Patients needing chronic RRT are at risk for severe COVID-19 and mount a lesser response to mRNA vaccination. We describe the impact of booster administration in these patients, amidst a third wave of infections and deaths. Methods In the setting of a prospective COVID-19-centred cohort study in dialysis and kidney transplant patients we examined humoral responses to booster vaccination, and subsequent infection risk. Results We quantified antibodies (DiaSorin) in 198 maintenance dialysis patients, 314 kidney transplant patients and 82 controls, without prior COVID-19 infection. Prior to boosting, 79% of controls, 35% of dialysis and 11% of transplant patients had levels [≥]59 AU/ml (putatively protective), while 8-54 days after a third injection, respective rates were 100%, 93% and 58%. Risk factors for antibodies <60 AU/ml despite booster injection were transplant vs dialysis, OR=18.4 (p<0.0001), transitioning from dialysis to transplantation or vice versa, OR=15.7 (p<0.01) and days post injection, OR=0.953 (p<0.05). Antibody step-up after the booster inversely correlated with the second dose step-up (r=-0.33, p<0.01). In this surge, 2 controls, 2 dialysis and 9 transplant patients had COVID-19. Antibody level [≥]59 AU/ml at any time point independently associated with reduced risk of infection during this surge, OR=0.264 (p=0.048). Conclusions We show that a third dose of tozinameran boosts antibody levels in patients receiving RRT, as it did in controls. Most patients have now reached antibody levels likely to protect from infection. Antibodies were higher after the third dose compared to previous peaks, which may hint that the latest immune response may be more robust and sustainable, even in immune-compromised patients. Kidney transplant recipients showed the most striking enhancement, exhibiting >5.5-fold increase in the percentage of patients with protective antibody levels. However, many transplant patients remain below threshold even after boost injection, necessitating further boosting strategies.
Catégories: Actus Santé

Genome-wide association study of 1,391 plasma metabolites in 6,136 Finnish men identifies 303 novel signals and provides biological insights into human diseases

Few studies have explored the impact of rare variants (minor allele frequency, MAF<1%) on highly heritable plasma metabolites identified in metabolomic screens. The Finnish population provides an ideal opportunity for such explorations, given the multiple bottlenecks and expansions that have shaped its history, and the enrichment for many otherwise rare alleles that has resulted. Here, we report genetic associations for 1,391 plasma metabolites in 6,136 men from the late-settlement region of Finland. We identify 303 novel association signals, more than one third at variants rare or enriched in Finns. Many of these signals identify genes not previously implicated in metabolite genome-wide association studies and suggest mechanisms for diseases and disease-related traits.
Catégories: Actus Santé

Association of Network Connectivity via Resting State Functional MRI with Consciousness, Mortality, and Outcomes in Neonatal Acute Brain Injury

Background An accurate and comprehensive test of integrated brain network function is needed for neonates during the acute brain injury period to inform on morbidity. This retrospective cohort study aimed to assess whether integrated brain network function by resting state functional MRI, acquired during the acute period in neonates with brain injury, is associated with acute exam, neonatal mortality, and 5-month outcomes. Methods This study included 40 consecutive neonates with resting state functional MRI acquired 1-22 days after suspected brain insult from March 2018 to July 2019 at Phoenix Childrens Hospital. Acute period exam and test results were assigned ordinal scores based on severity as documented by respective treating specialists. Analyses (Fisher exact, Wilcoxon-rank sum test, ordinal/multinomial logistic regression) examined association of resting state networks with demographics, presentation, neurological exam, electroencephalogram, anatomical MRI, magnetic resonance spectroscopy, passive task functional MRI, and outcomes of discharge condition, outpatient development, motor tone, seizure, and mortality. Results Subjects had a mean (standard deviation) gestational age of 37.8 (2.6) weeks, a majority were male (63%), with diagnosis of hypoxic ischemic encephalopathy (68%). Other findings at birth included mild distress (48%), moderately abnormal neurological exam (33%), and consciousness characterized as awake but irritable (40%). Significant associations after multiple testing corrections were detected for resting state networks: basal ganglia with outpatient developmental delay (odds ratio [OR], 14.5; 99.4% confidence interval [CI], 2.00-105; P<.001) and motor tone/weakness (OR, 9.98; 99.4% CI, 1.72-57.9; P<.001); language/frontal-parietal network with discharge condition (OR, 5.13; 99.4% CI, 1.22-21.5; P=.002) and outpatient developmental delay (OR, 4.77; 99.4% CI, 1.21-18.7; P=.002); default mode network with discharge condition (OR, 3.72; 99.4% CI, 1.01-13.78; P=.006) and neurological exam (P=.002 (FE); OR, 11.8; 99.4% CI, 0.73-191; P=.01 (OLR)); seizure onset zone with motor tone/weakness (OR, 3.31; 99.4% CI, 1.08-10.1; P=.003). Resting state networks were not detected in only three neonates, who died prior to discharge. Conclusions This study provides level 3 evidence (OCEBM Levels of Evidence Working Group) that the degree of abnormality of resting state networks in neonatal acute brain injury is associated with acute exam and outcomes. Total lack of brain network detection was only found in patients who did not survive.
Catégories: Actus Santé

Evaluation of a speech-based AI system for early detection of Alzheimer's disease remotely via smartphones

Background: Changes in speech, language, and episodic and semantic memory are documented in Alzheimer's disease (AD) years before routine diagnosis. Aims: Develop an Artificial Intelligence (AI) system detecting amyloid-confirmed prodromal and preclinical AD from speech collected remotely via participants' smartphones. Method: A convenience sample of 133 participants with established amyloid beta and clinical diagnostic status (66 A{beta} +, 67 A{beta} -; 71 cognitively unimpaired (CU), 62 with mild cognitive impairment (MCI) or mild AD) completed clinical assessments for the AMYPRED study (NCT04828122). Participants completed optional remote assessments daily for 7-8 days, including the Automatic Story Recall Task (ASRT), a story recall paradigm with short and long variants, and immediate and delayed recall phases. Vector-based representations from each story source and transcribed retelling were produced using ParaBLEU, a paraphrase evaluation model. Representations were fed into logistic regression models trained with tournament leave-pair-out cross-validation analysis, predicting A{beta} status and MCI/mild AD within the full sample and A{beta} status in clinical diagnostic subsamples. Findings: At least one full remote ASRT assessment was completed by 115 participants (mean age=69.6 (range 54-80); 63 female/52 male; 66 CU and 49 MCI/mild AD, 56 A{beta} + and 59 A{beta} -). Using an average of 2.7 minutes of automatically transcribed speech from immediate recall of short stories, the AI system predicted MCI/mild AD in the full sample (AUC=0.85 +/- 0.08), and amyloid in MCI/mild AD (AUC=0.73 +/- 0.14) and CU subsamples (AUC=0.71 +/- 0.13). Amyloid classification within the full sample was no better than chance (AUC=0.57 +/- 0.11). Broadly similar results were reported for manually transcribed data, long ASRTs and delayed recall. Interpretation: Combined with advanced AI language models, brief, remote speech-based testing offers simple, accessible and cost-effective screening for early stage AD. Funding: Novoic.
Catégories: Actus Santé

Ambient heat exposure and COPD hospitalisations in England: A nationwide case-crossover study during 2007-2018.

Background There is emerging evidence suggesting a link between ambient heat exposure and Chronic obstructive pulmonary disease (COPD) hospitalisations. Individual and contextual characteristics can affect population vulnerabilities to COPD hospitalisation due to heat exposure. This study quantifies the effect of ambient heat on COPD hospitalisations and examines population vulnerabilities by age, sex and contextual characteristics. Methods Individual data on COPD hospitalisation at high geographical resolution (postcodes) during 2007-2018 in England was retrieved from the small area health statistics unit. Maximum temperature at 1 kmx1km resolution was available from the UK Met Office. We employed a case-cross over study design and fitted Bayesian conditional Poisson regression models. We adjusted for PM2.5, O3, relative humidity and national holidays, and examined effect modification by age, sex, green space, average temperature, deprivation and urbanicity. Results After accounting for confounding, we found a 0.52% (95% Credible Interval 0.22% to 0.84%) increase in the hospitalisation risk for every 1oC increase in the lag 0-2 temperatures above 23.8oC. We reported weak evidence of an effect modification by sex and age. We found a strong spatial determinant of the COPD hospitalisation risk due to heat exposure, that was alleviated when we accounted for contextual characteristics. Assuming a causal effect, 6 280 (95% CrI 3 441 to 8 993) COPD hospitalisations were attributable to heat exposure. Conclusion Our study suggests that resources should be allocated to support the public health systems, for instance through developing or expanding heat-health alerts, to challenge the increasing future heat-related COPD hospitalisation burden.
Catégories: Actus Santé

Psychological, social and financial impact of COVID-19 on culturally and linguistically diverse communities: a cross-sectional Australian study

Objective: This study aimed to explore the psychological, social, and financial impacts of COVID-19 on culturally and linguistically diverse communities in Australia. Design: Cross-sectional survey informed by the Framework for Culturally Competent Health Research conducted between March and July, 2021. Setting: Participants were recruited from Greater Western Sydney, New South Wales, Australia. Participants: 708 community members who speak a language other than English at home participated (mean age: 45.4years [range 18 to 91]; 88% [n=622] born outside of Australia). Outcome measures: Fifteen items regarding impacts of COVID-19, adapted from validated scales, previous surveys or co-designed in partnership with Multicultural Health and interpreter service staff. Logistic regression models (using post-stratification weighted frequencies) identified factors associated with psychological, social, and financial impacts. Surveys were available in English or translated (11 languages). Results: Even prior to the COVID-19 outbreak in Sydney, 25% of the sample reported feeling nervous or stressed most/all of the time and 22% felt lonely or alone most/all of the time. One quarter of participants reported negative impacts on their spousal relationships as a result of COVID-19 and most parents reported that their children were less active (64%), had more screen time (63%), and were finding school harder (45%). Mean financial burden was 2.9/5 (95%CI=2.8 to 2.9). Regression analyses consistently showed distinct impact patterns for different language groups and more negative outcomes for those with comorbidities. Conclusion: Culturally and linguistically diverse communities experience significant psychological, social and financial impacts of COVID-19, with distinct impact patterns across language groups. A whole-of-government approach with policy and sustainable infrastructure is needed to co-design innovative, tailored and culturally-safe COVID-19 support packages.
Catégories: Actus Santé

Wastewater and surface monitoring to detect COVID-19 in elementary school settings: The Safer at School Early Alert project

Schools are high-risk settings for SARS-CoV-2 transmission, but necessary for children's educational and social-emotional wellbeing. While wastewater monitoring has been implemented to mitigate outbreak risk in universities and residential settings, its effectiveness in community K-12 sites is unknown. We implemented a wastewater and surface monitoring system to detect SARS-CoV-2 in nine elementary schools in San Diego County. Ninety-three percent of identified cases were associated with either a positive wastewater or surface sample; 67% were associated with a positive wastewater sample, and 40% were associated with a positive surface sample. The techniques we utilized allowed for near-complete genomic sequencing of wastewater and surface samples. Passive environmental surveillance can complement approaches that require individual consent, particularly in communities with limited access and/or high rates of testing hesitancy.
Catégories: Actus Santé

Factors affecting the mental health of pregnant women using UK maternity services during the COVID-19 pandemic: A qualitative interview study.

Background: People using maternity services in the United Kingdom (UK) have faced significant changes brought on by the COVID-19 pandemic and social distancing regulations. We focused on the experiences of pregnant women using UK maternity services during the pandemic and the impact of social distancing rules on their mental health and wellbeing. Methods: We conducted 23 qualitative semi-structured interviews from June 2020 to August 2021, with women from across the UK who experienced a pregnancy during the pandemic. Nineteen women in the study carried their pregnancy to term and four women experienced a miscarriage during the pandemic. Interviews took place remotely over video or telephone call, discussing topics such as mental health during pregnancy and use of UK maternity services. We used reflexive thematic analysis to analyse interview transcripts. Results: We generated six higher order themes: (1) Some pregnancy discomforts alleviated by social distancing measures, (2) The importance of relationships that support coping and adjustment, (3) Missed pregnancy and parenthood experiences, (4) The mental health consequences of birth partner and visitor restrictions, (5) Maternity services under pressure, and (6) Lack of connection with staff. Many participants felt a sense of loss over a pregnancy experience that differed so remarkably to what they had expected because of the pandemic. Supportive relationships were important to help cope with pregnancy and pandemic-related changes; but feelings of isolation were compounded for some participants because opportunities to build social connections through face-to-face parent groups were unavailable. Participants also described feeling alone due to restrictions on partners being present when accessing UK maternity services. Conclusions: Our findings highlight some of the changes that may have affected pregnant womens mental health during the COVID-19 pandemic. Reduced social support and being unable to have a partner or support person present during maternity service use were the greatest concerns reported by women in this study, as this absence removed a protective buffer in times of uncertainty and distress. This suggests that the availability of a birth partner or support person must be prioritised wherever possible to protect the mental health of women experiencing pregnancy and miscarriage in times of pandemics.
Catégories: Actus Santé

Metabolic Dysfunction-Related Liver Disease as a Risk Factor for Cancer

The aim of this study was to investigate the association with obesity, diabetes and related liver dysfunction and the incidence of cancer. This study was conducted with health record data available from the National Health Service in Tayside and Fife. GoDARTS, SHARE and Tayside and Fife diabetics, three Scottish cohorts of 13,695, 62,438, and 16,312 patients respectively were analysed in this study. Participants in GoDARTS were a volunteer sample, with half having T2DM. SHARE were a volunteer sample. Tayside and Fife diabetics was a population level cohort. Metabolic dysfunction-related liver disease (MDLD) was defined using ALT measurements, and individuals with alternative causes of liver disease (alcohol abuse, viruses etc) were excluded from the analysis. Other indicators of liver disease were analysed including the Fatty Liver Index, Fibrosis Score(FIB-4) and hospital admissions for NASH. The main outcomes were cancer incidence and cancer death. MDLD associated with increased cancer incidence with a hazard ratio of 1.31 in a cox proportional hazards model adjusted for sex, type 2 diabetes, BMI, and smoking status (95% CI = 1.27 - 1.35, p < 0.0001). This was replicated in two further cohorts, and similar associations with cancer incidence were found for Fatty Liver Index (FLI), FIB-4 and NASH. Homozygous carriers of the common NAFLD risk variant PNPLA3 rs738409 had increased risk of cancer. (HR = 1.27 (1.02-1.58), p = 0.031 ). BMI was not independently associated with cancer incidence when MDLD was included as a covariate. MDLD was associated with increased risk of cancer death (HR = 1.40, 95% CI =1.33 - 1.47, p < 0.0001). MDLD, FLI, FIB-4 and NASH associated with increased risk of cancer incidence and death. Further, we found evidence of a causal association between NAFLD and cancer using the established causal risk allele of PNPLA3 as a genetic instrument. NAFLD may be a major component of the relationship between obesity and cancer incidence.
Catégories: Actus Santé

Immunogenicity of BNT162b2 Vaccine in Patients with Inflammatory Bowel Disease on Infliximab Combination Therapy: A Multicenter Prospective Study

Background Vaccination is a promising strategy to protect vulnerable groups like inflammatory bowel disease (IBD) patients against COVID-19 and associated severe outcomes. COVID-19 Vaccines clinical trials excluded IBD patients taking infliximab with azathioprine or 6-mercaptopurine (infliximab combination). Therefore, we sought to evaluate serologic responses to COVID-19 vaccination with the mRNA vaccine, BNT162b2 in IBD patients receiving infliximab combination therapy compared to healthy participants. Methods This is a multicenter prospective study. IBD patients were recruited at the time of attendance at infusion center between August 1st, 2021, and September 15th, 2021. Our primary outcome was the concentrations of SARS-CoV-2 antibodies 4-10 weeks after vaccination with two doses of BNT162b2 vaccine in IBD patients taking infliximab combination therapy (study group) compared to healthy participants group (control group). Both study and healthy participants groups were matched for age, sex and time-since-last-vaccine-dose using optimal pair matching method. Results In total 116 participants were recruited in the study, 58 patients in the study group and 58 in the control group. Median (IQR) IgG concentrations were lower in the study group [99 BAU/mL (40, 177)] than the control group [139 BAU/mL (120, 188)], following vaccination (p = 0.0032). Neutralizing antibodies was also lower in the study group compared to the control group [64% (23, 94) vs 91% (85, 94), p <0.001]. The median IgA levels in the study group was also significantly lower when compared to the control group [6 U/ml (3, 34) vs 13 U/ml (7, 30), p =0.0097]. In the study group, the percentage of patients who achieved positive IgG, neutralizing antibody and IgA levels were 81%, 75% and 40% respectively. In the control group, all participants (100%) had positive IgG and neutralizing antibody levels while 62% had positive IgA levels. Conclusion In patients with IBD receiving infliximab combination therapy, IgG, IgA and neutralizing antibody levels after BNT162b2 vaccine were lower compared to healthy participants. However, most patients treated with infliximab combination therapy seroconverted after two doses of the vaccine.
Catégories: Actus Santé

Extreme COVID-19 waves reveal hyperexponential growth and finite-time singularity

Coronavirus disease 2019 (COVID-19) has rapidly spread throughout our planet, bringing human lives to a standstill. Understanding the early transmission dynamics helps plan intervention strategies such as lockdowns that mitigate further spread, minimizing the adverse impact on humanity and the economy. Exponential growth of infections was thought to be the defining feature of an epidemic in its initial growth phase. Contrary to common belief, early stages of extreme COVID-19 waves display an unbounded growth and finite-time singularity accompanying a hyperexponential power-law. The faster than exponential growth phase is hazardous and would entail stricter regulations. Such power-law description allows us to characterize COVID-19 waves with single power-law exponents, better than piecewise exponentials. Furthermore, we identify the presence of log-periodic patterns decorating the power-law growth. These log-periodic oscillations may enable better prediction of the finite-time singularity. We anticipate that our findings of hyperexponential growth and log-periodicity will help model the COVID-19 transmission more accurately.
Catégories: Actus Santé

Impact of routine asymptomatic screening on COVID-19 incidence in a highly vaccinated university population

Background: With the return of in-person classes, an understanding of COVID-19 transmission in vaccinated university campuses is essential. Given the context of high anticipated vaccination rates and other measures, there are outstanding questions of the potential impact of campus-based asymptomatic screening. Methods: We estimated the expected number of cases and hospitalizations in one semester using rates derived for British Columbia (BC), Canada up to September 15th, 2021 and age-standardizing to a University population. To estimate the expected number of secondary cases averted due to routine tests of unvaccinated individuals in a BC post-secondary institution, we used a probabilistic model based on the incidence, vaccination effectiveness, vaccination coverage and R0. We examined multiple scenarios of vaccine coverage, screening frequency, and pre-vaccination R0. Results: For one 12 week semester, the expected number of cases is 67 per 50,000 for 80% vaccination coverage and 37 per 50,000 for 95% vaccination coverage. Screening of the unvaccinated population averts an expected 6-16 cases per 50,000 at 80% decreasing to 1-2 averted cases per 50,000 at 95% vaccination coverage for weekly to daily screening. Further scenarios can be explored using a web-based application. Interpretation: Routine screening of unvaccinated individuals may be of limited benefit if vaccination coverage is 80% or greater within a university setting.
Catégories: Actus Santé

SARS-COV-2 δ variant drives the pandemic in India and Europe via two subvariants

SARS-COV-2 evolution generates different variants and drives the pandemic. As the current main driver, delta variant bears little resemblance to the other three variants of concern, raising the question what features future variants of concern may possess. To address this important question, I compared different variant genomes and specifically analyzed delta genomes in the GISAID database for potential clues. The analysis revealed that delta genomes identified in India by April 2021 form four different groups (referred to as delta1, delta2, delta3 and delta4) with signature spike, nucleocapsid and NSP3 substitutions defining each group. Since May 2021, delta1 has gradually overtaken all other subvariants and become the dominant pandemic driver, whereas delta2 has played a less prominent role and the remaining two (delta3 and delta4) are insignificant. This group composition and variant transition are also apparent across Europe. In the United Kingdom, delta1 has quickly become predominant and is the sole pandemic driver underlying the current wave of COVID-19 cases. Alarmingly, delta1 subvariant has evolved further in the country and yielded a sublineage encoding spike V36F, A222V and V1264L. These substitutions may make the sublineage more virulent than delta1 itself. In the rest of Europe, delta1 is also the main pandemic driver, but delta2 still plays a role. In many European countries, there is a delta1 sublineage encoding spike T29A, T250I and Q613H. This sublineage originated from Morocco and has been a key pandemic driver there. Therefore, delta variant drives the pandemic in India and across Europe mainly through delta1 and delta2, with the former acquiring additional substitutions and yielding sublineages with the potential to drive the pandemic further. These results suggest a continuously branching model by which delta variant evolves and generates more virulent subvariants.
Catégories: Actus Santé

Impacts of vaccination and Severe Acute Respiratory Syndrome Coronavirus 2 variants Alpha and Delta on Coronavirus Disease 2019 transmission dynamics in the 15 most populous metropolitan statistical areas in the United States

To characterize Coronavirus Disease 2019 (COVID-19) transmission dynamics in each of the 15 most populous metropolitan statistical areas (MSAs) in the United States (US) from January 2020 to September 2021, we extended a previously reported compartmental model accounting for effects of multiple distinct periods of social distancing by adding consideration of vaccination and Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) variants Alpha (lineage B.1.1.7) and Delta (lineage B.1.617.2). For each MSA, we found region-specific parameterizations of the model using daily reports of new COVID-19 cases available from January 21, 2020 to August 24, 2021. In the process, we obtained estimates of the relative infectiousness of Alpha and Delta as well as their takeover times in each MSA. We find that 14-d ahead forecasts are reasonably accurate; these forecasts are being updated daily. Projections made on August 24, 2021 suggest that 5 of the 15 MSAs have already achieved herd immunity.
Catégories: Actus Santé

Comparative effectiveness of allocation strategies of COVID-19 vaccines and antivirals against emerging SARS-CoV-2 variants of concern in East Asia and Pacific region

Background We aimed to evaluate the impact of various allocation strategies of COVID-19 vaccines and antiviral such that the pandemic exit strategy could be tailored to risks and preferences of jurisdictions in the East Asia and Pacific region (EAP) to improve its efficiency and effectiveness. Methods Vaccine efficacies were estimated from the titre distributions of 50% plaque reduction neutralization test (PRNT50), assuming that PRNT50 titres of primary vaccination decreased by 2-10 folds due to antibody waning and emergence of VOCs, and an additional dose of vaccine would increase PRNT50 titres by 3- or 9-fold. We then used an existing SARS-CoV-2 transmission model to assess the outcomes of vaccine allocation strategies with and without the use of antivirals for symptomatic patients in Japan, Hong Kong and Vietnam. Findings Increasing primary vaccination coverage was the most important contributing factor in reducing the total and peak number of COVID-19 hospitalizations, especially when population vaccine coverage or vaccine uptake among older adults was low. Providing antivirals to 50% of symptomatic infections only further reduced total and peak hospitalizations by 10-13%. The effectiveness of an additional dose of vaccine was highly dependent on the immune escape potential of VOCs and antibody waning, but less dependent on the boosting efficacy of the additional dose. Interpretation Increasing primary vaccination coverage should be prioritised in the design of allocation strategies of COVID-19 vaccines and antivirals in the EAP region. Heterologous vaccination with any available vaccine as the additional dose could be considered when planning pandemic exit strategies tailored to the circumstances of EAP jurisdictions.
Catégories: Actus Santé

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