science journals, jobs, information and services.

https://www.nature.com

  • Olfactory transmucosal #SARS-CoV-2 invasion as a port of central nervous system entry in individuals with COVID-19 | Nature Neuroscience
    https://www.nature.com/articles/s41593-020-00758-5

    Étude post-mortem sur des humains.

    ... experts from the fields of neuropathology, pathology, forensic medicine, virology and clinical care studied tissue samples from 33 patients (average age 72) who had died at either Charité or the University Medical Center Göttingen after contracting COVID-19. Using the latest technology, the researchers analyzed samples taken from the deceased patients’ olfactory mucosa and from four different brain regions. Both the tissue samples and distinct cells were tested for SARS-CoV-2 genetic material and a ’spike protein’ which is found on the surface of the virus. The team provided evidence of the virus in different neuroanatomical structures which connect the eyes, mouth and nose with the brain stem. The olfactory mucosa revealed the highest viral load. Using special tissue stains, the researchers were able to produce the first-ever electron microscopy images of intact coronavirus particles within the olfactory mucosa . These were found both inside nerve cells and in the processes extending from nearby supporting (epithelial) cells.

  • What the data say about asymptomatic #COVID infections
    https://www.nature.com/articles/d41586-020-03141-3

    Définition : Au moins 7 jours de suivi sans symptômes
    20% des sujets infectés sont asymptomatiques ;
    contagieux mais moindre que les symptomatiques ;
    leur rôle dans la propagation n’est pas capital
    Leur charge virale est initialement aussi importante que les symptomatiques (d’où la nécessité des mesures barrière malgré tout) mais diminue plus rapidement.

    Research early in the pandemic suggested that the rate of asymptomatic infections could be as high as 81%. But a meta-analysis published last month1, which included 13 studies involving 21,708 people, calculated the rate of asymptomatic presentation to be 17%. The analysis defined asymptomatic people as those who showed none of the key COVID-19 symptoms during the entire follow-up period, and the authors included only studies that followed participants for at least seven days. Evidence suggests that most people develop symptoms in 7–13 days, says lead author Oyungerel Byambasuren, a biomedical researcher at the Institute for Evidence-Based Healthcare at Bond University in Gold Coast, Australia.

    Byambasuren’s review also found that asymptomatic individuals were 42% less likely to transmit the virus than symptomatic people.

    One reason that scientists want to know how frequently people without symptoms transmit the virus is because these infections largely go undetected. Testing in most countries is targeted at those with symptoms.

    As part of a large population study in Geneva, Switzerland, researchers modelled viral spread among people living together. In a manuscript posted on medRxiv this month2, they report that the risk of an asymptomatic person passing the virus to others in their home is about one-quarter of the risk of transmission from a symptomatic person.

    Although there is a lower risk of transmission from asymptomatic people, they might still present a significant public-health risk because they are more likely to be out in the community than isolated at home, says Andrew Azman, an infectious-disease epidemiologist at the Johns Hopkins Bloomberg School of Public Health in Baltimore, Maryland, who is based in Switzerland and was a co-author on the study. “The actual public-health burden of this massive pool of interacting ‘asymptomatics’ in the community probably suggests that a sizeable portion of transmission events are from asymptomatic transmissions,” he says.

    But other researchers disagree about the extent to which asymptomatic infections are contributing to community transmission. If the studies are correct in finding that asymptomatic people are a low transmission risk, “these people are not the secret drivers of this pandemic”, says Byambasuren. They “are not coughing or sneezing as much, they’re probably not contaminating as much surfaces as other people”.

    Muge Cevik, an infectious-disease researcher at the University of St Andrews, UK, points out that because most people are symptomatic, concentrating on identifying them will probably eliminate most transmission events.

    Viral dynamics

    To understand what is happening in people with no symptoms, Cevik and colleagues conducted a systematic review and meta-analysis3 of 79 studies on the viral dynamics and transmissibility of SARS-CoV-2, which is posted on social-sciences preprint server SSRN. Some studies showed that those without symptoms had similar initial viral loads — the number of viral particles present in a throat swab — when compared with people with symptoms. But asymptomatic people seem to clear the virus faster and are infectious for a shorter period.

    The immune systems of asymptomatic individuals might be able to neutralize the virus more rapidly, says Cevik. But that doesn’t mean these people have a stronger or more durable immune response — and there is evidence that people with severe COVID-19 have a more substantial and long-lasting neutralizing antibody response, she says.

    Although there is a now a better understanding of asymptomatic infections and transmission of COVID-19, Cevik says that asymptomatic people should continue to use measures that reduce viral spread, such as social distancing, hand hygiene and wearing a mask.

    References

    1. Byambasuren, O. et al. J. Assoc. Med. Microbiol. Infect. Dis. Can. https://doi.org/10.3138/jammi-2020-0030 (2020).

    #asymptomatique #contagiosité

  • Ranking the effectiveness of worldwide COVID-19 government interventions | Nature Human Behaviour
    https://www.nature.com/articles/s41562-020-01009-0/figures

    Assessing the effectiveness of non-pharmaceutical interventions (NPIs) to mitigate the spread of SARS-CoV-2 is critical to inform future preparedness response plans. Here we quantify the impact of 6,068 hierarchically coded NPIs implemented in 79 territories on the effective reproduction number, Rt, of COVID-19. We propose a modelling approach that combines four computational techniques merging statistical, inference and artificial intelligence tools. We validate our findings with two external datasets recording 42,151 additional NPIs from 226 countries. Our results indicate that a suitable combination of NPIs is necessary to curb the spread of the virus. Less disruptive and costly NPIs can be as effective as more intrusive, drastic, ones (for example, a national lockdown). Using country-specific ‘what-if’ scenarios, we assess how the effectiveness of NPIs depends on the local context such as timing of their adoption, opening the way for forecasting the effectiveness of future interventions.

    aussi référencé ici https://seenthis.net/messages/887290

    • En français (bibi+tesseract+deepl+remplacement firefox html/css+capture d’écran)

      Small gathering cancellation
      Closure of educational institutions
      Border restriction
      Increase availability of PPE
      Individual movement restrictions
      National lockdown
      Mass gathering cancellation
      Educate and actively communicate with the public
      The government provides assistance to vulnerable populations
      Actively communicate with managers
      Measures for special populations
      Increase in healthcare workforce
      Quarantine
      Activate or establish emergency response
      Enhance detection system
      Increase in medical supplies and equipment
      Police and army interventions
      Travel alert and warning
      Public transport restriction
      Actively communicate with healthcare professionals
      Airport restriction
      Crisis management plans
      Increase in patient capacity
      Adapt procedures for patient management
      Special measures for certain establishments
      Research
      Personal protective measures
      Tracing and tracking
      Border health check
      Cordon sanitaire
      Port and ship restriction
      Work safety protocols
      Isolation of cases
      Repurpose hospitals
      Environmental cleaning and disinfection
      Measures to ensure security of supply
      Return operation of nationals
      Provide international help
      Restricted testing
      Activate case notification
      Surveillance
      Airport health check
      Measures for public transport
      Increase in isolation and quarantine facilities
      Enhance laboratory testing capacity
      Receive international help
      -

  • Immunity to the #Coronavirus May Last Years, New Data Hint - The New York Times
    https://www.nytimes.com/2020/11/17/health/coronavirus-immunity.html

    The research, published online, has not been peer-reviewed nor published in a scientific journal. But it is the most comprehensive and long-ranging study of immune memory to the coronavirus to date.

    “That amount of memory would likely prevent the vast majority of people from getting hospitalized disease, severe disease, for many years,” said Shane Crotty, a virologist at the La Jolla Institute of Immunology who co-led the new study.

    The findings are likely to come as a relief to experts worried that immunity to the virus might be short-lived, and that vaccines might have to be administered repeatedly to keep the pandemic under control.

    [..,]

    A study published last week also found that people who have recovered from #Covid-19 have powerful and protective killer immune cells even when antibodies are not detectable .

    These studies “are all by and large painting the same picture, which is that once you get past those first few critical weeks, the rest of the response looks pretty conventional,” said Deepta Bhattacharya, an immunologist at the University of Arizona.

    Akiko Iwasaki, an immunologist at Yale University, said she was not surprised that the body mounts a long-lasting response because “that’s what is supposed to happen.” Still, she was heartened by the research: “This is exciting news.”

    Sources :

    Immunological memory to #SARS-CoV-2 assessed for greater than six months after infection | bioRxiv
    https://www.biorxiv.org/content/10.1101/2020.11.15.383323v1

    Characterization of pre-existing and induced SARS-CoV-2-specific CD8 + T cells | Nature Medicine
    https://www.nature.com/articles/s41591-020-01143-2

    #immunité_cellulaire #immunité

  • Découverte surprenante de millions d’arbres dans le désert du Sahara
    https://www.tameteo.com/actualites/actualite/decouverte-surprenante-de-millions-d-arbres-dans-le-desert-du-sahara.html

    Le Sahara, le plus grand désert non polaire du monde, recèle des secrets cachés difficiles à percer. Récemment, une nouvelle étude a conclu que plus de 1,8 milliard d’arbres y vivent. Il ne s’agit pas de forêts, mais d’arbres solitaires.

    Les travaux menés par le scientifique Martin Brandt (Université de Copenhague), publiés dans la revue Nature, ont réussi à dénombrer ces arbres un à un sur une superficie de 1,3 million de km2 en Afrique du Nord-Ouest.

    Brandt et ses collègues ont analysé 11 128 images satellites avec une résolution de 0,5 mètre. Ils ont utilisé des algorithmes d’apprentissage en profondeur pour cartographier les arbres sur une vaste zone couvrant le désert du Sahara en Afrique de l’Ouest, la région semi-aride du Sahel et une zone humide au sud. La région traverse des pays comme l’Algérie, la Mauritanie, le Sénégal et le Mali.

    https://www.nature.com/articles/s41586-020-2824-5

  • Age-specific mortality and immunity patterns of SARS-CoV-2 | Nature
    https://www.nature.com/articles/s41586-020-2918-0

    #COVID-19 : Les décès chez les moins de 65 ans, un indicateur fiable de #transmission | santé log
    https://www.santelog.com/actualites/covid-19-les-deces-chez-les-moins-de-65-ans-un-indicateur-fiable-de-transm

    Cette étude de chercheurs de l’Université de Cambridge et de l’Institut Pasteur, publiée dans la revue Nature souligne que les décès liés au COVID-19 sont un indicateur utile pour suivre la transmission de l’épidémie, au niveau de chaque pays. A condition peut-être d’exclure les décès intervenus dans les groupes d’âge plus élevé : les décès intervenus dans les maisons de retraite européennes et les données manquantes en provenance de certains pays d’Asie et d’Amérique du Sud ont pu fausser les estimations de taux de mortalité chez ces groupes d’âge plus avancé.

    Pour ces raisons de différences d’enregistrement et de déclaration selon les pays, la simple comparaison des taux de décès entre pays apporte très probablement une représentation trompeuse des niveaux de transmission du virus, soulignent les auteurs. En revanche, la notification des décès liés au COVID-19 chez les moins de 65 ans est un indicateur probablement bien plus fiable, peut apporter un éclairage précieux sur la transmission du virus, et permettre de meilleures comparaisons entre pays – ce qui peut également permettre d’évaluer l’efficacité des différentes stratégies.

  • Harms of public health interventions against covid-19 must not be ignored | The BMJ
    https://www.bmj.com/content/371/bmj.m4074

    The harmful consequences of public health interventions can be direct or indirect—for example, psychological harms, equity harms, group and social harms, opportunity harms, and inequalities in intervention benefits.12 These interventions can increase the adverse outcomes they seek to prevent or affect other health outcomes.234 Policy makers, acting to protect public health, need to weigh the possible side effects when deciding on, implementing, and evaluating specific public health interventions.1

    Public policy efforts that have been implemented to deal with the covid-19 pandemic have been caught in a political maelstrom precisely because these efforts, in their first iteration, did not consider the potential negative consequences. Although policies to bring about mass social distancing may have slowed viral spread, they also brought about unprecedented levels of unemployment that led to justifiable resistance from some sectors. Had these policy efforts explicitly considered these consequences from the start—and social distancing has long been an element of planning for a severe pandemic—this would have obviated some of the political backlash, leading to more uniform and more effective implementation of these policies.

  • Why big pharma has abandoned antibiotics (Nature)
    https://www.nature.com/articles/d41586-020-02884-3

    Despite the clear need for more antimicrobial agents, such drugs have not been forthcoming. Fewer new antibiotics are reaching the market; the last entirely original class of antibiotic was discovered in the late 1980s. One reason is that discovering and bringing antibiotics to market is often not profitable for pharmaceutical companies.

  • La #Dépakine multiplie par cinq le risque de troubles du développement
    https://www.lemonde.fr/societe/article/2020/10/22/la-depakine-multiplie-par-cinq-le-risque-de-troubles-du-developpement_605701

    Le nom générique de la Depakine est « valproate » ou acide valproïque ». En dehors de « Depakine » il existe d’autres noms commerciaux de valproate sur le marché.

    L’article* montre par ailleurs qu’il n’y a pas d’augmentation du risque chez les enfants exposés au #valproate « uniquement pendant le premier trimestre » de #grossesse, alors que « les études disponibles ne permettaient pas d’établir si le risque différait selon la période d’exposition », souligne la chercheuse. Il conclut également que « le risque est plus faible chez les enfants exposés à de plus faibles doses du médicament que chez ceux exposés à des doses plus élevées ».

    Autre enseignement : « Le risque de troubles neuro-développementaux précoces associé aux autres antiépileptiques, notamment la lamotrigine, apparaît beaucoup moins marqué. Cependant, le risque (…) après une exposition in utero à la prégabaline », augmenté de 50 % selon l’étude, « nécessite d’être surveillé et doit faire l’objet d’études complémentaires », souligne l’épidémiologiste.

    « Le niveau des connaissances » pour les autres traitements de l’#épilepsie était jusqu’ici « hétérogène et généralement insuffisant pour permettre une conclusion définitive sur le risque de troubles neuro-développementaux », ajoute Rosemary Dray-Spira. Selon les recommandations de la Haute Autorité de santé, les alternatives au valproate dans l’épilepsie sont la lamotrigine (à privilégier) puis le lévétiracétam et l’oxcarbazépine.

    * Risk of early neurodevelopmental disorders associated with in utero exposure to valproate and other antiepileptic drugs: a nationwide cohort study in France | Scientific Reports
    https://www.nature.com/articles/s41598-020-74409-x

  • Modeling #COVID-19 scenarios for the United States | Nature Medicine
    https://www.nature.com/articles/s41591-020-1132-9

    Projections of current non-pharmaceutical intervention strategies by state—with social distancing mandates reinstated when a threshold of 8 deaths per million population is exceeded (reference scenario)—suggest that, cumulatively, 511,373 (469,578–578,347) lives could be lost to COVID-19 across the United States by 28 February 2021. We find that achieving universal mask use (95% mask use in public) could be sufficient to ameliorate the worst effects of epidemic resurgences in many states.

    Universal mask use could save an additional 129,574 (85,284–170,867) lives from September 22, 2020 through the end of February 2021, or an additional 95,814 (60,731–133,077) lives assuming a lesser adoption of mask wearing (85%), when compared to the reference scenario.

    #masques

  • Magnitude, demographics and dynamics of the effect of the first wave of the COVID-19 pandemic on all-cause mortality in 21 industrialized countries | Nature Medicine
    https://www.nature.com/articles/s41591-020-1112-0

    #Covid-19 : les leçons à tirer de la #surmortalité lors de la première vague, pays par pays - Le Parisien
    https://www.leparisien.fr/societe/covid-19-les-lecons-a-tirer-de-la-surmortalite-lors-de-la-premiere-vague-

    Saisissantes, les différences d’un pays à l’autre sont pour les auteurs de l’étude le reflet de « la façon dont chacun a géré l’épidémie ainsi que de la préparation et la résistance du système social et de santé ». Parmi ces facteurs, il y a notamment la mise en place d’un traçage efficace des cas contacts ou le moment auquel le confinement est entré en vigueur.

    « Ceux qui ont pris cette mesure un peu trop tardivement se sont retrouvés avec des taux de mortalité en excès plus forts », souligne Michel Guillot. Trois des quatre pays ayant connu la plus haute surmortalité ont attendu d’avoir plus de 10 000 cas de coronavirus recensés et plusieurs centaines de morts liés au Covid-19 pour prendre une telle mesure.

    Le rôle central des investissements dans la santé

    Le taux de surmortalité semble aussi fortement corrélé aux #investissements dans le système de #santé. A l’exception de la Belgique, les sept pays avec les taux de décès excédentaires les plus élevés disposent de moins de 3,5 lits d’hôpitaux pour 1 000 habitants, contre 6,4 lits pour 100 000 habitants en France et 7,6 lits en Autriche.

    « Dans les endroits où le nombre de lits d’hôpitaux est limité, la peur d’être débordé peut avoir mené à retarder l’admission des malades atteints du Covid-19 et des autres patients jusqu’à une détérioration de leur état », expliquent les auteurs. « Nous ne pouvons pas démanteler le système de santé pour cause d’#austérité et ensuite s’attendre à ce qu’il prenne soin des gens au moment où le besoin est à son comble, particulièrement au sein des sous-populations #pauvres et marginalisées », abonde dans un communiqué Majid Ezzati, auteur principal de l’étude et chercheur à l’Ecole de #Santé_Publique de l’Imperial College.

  • Ending hunger : science must stop neglecting smallholder farmers
    https://www.nature.com/articles/d41586-020-02849-6

    Un groupe international de chercheurs (#Ceres2030) a épluché plus de 100.000 articles en 3 ans sur la #faim et les moyens d’y remédier ; leurs constatations sont accablantes : les solutions efficaces, en particulier l’aide aux fermes les plus importantes, celles de petite taille, ne sont retrouvées que dans une “infime” partie de ces publications.

    The team was able to identify ten practical interventions that can help donors to tackle hunger, but these were drawn from only a tiny fraction of the literature. The Ceres2030 team members found that the overwhelming majority of the agricultural-research publications they assessed were unable to provide solutions , particularly to the challenges faced by smallholder farmers and their families.

    [...]

    By contrast, the project team found a preponderance of studies on new technologies. Every year, food rots in the field, or later on, because of inadequate storage. But nearly 90% of interventions aiming to reduce these losses looked at how well a particular tool, such as a pesticide or a storage container, worked in isolation. Only around 10% compared the many existing agricultural practices to evaluate what works and what doesn’t.

    Pourquoi ? Parce que « plus de la moitié du financement de la recherche sur ce domaine est assuré par le secteur #privé », nommément l’#agribusiness, et parce que le système est fait de telle manière (maximum de publications) que ledit secteur est le meilleur moyen de faire #carrière pour les #chercheurs.

    So why aren’t more researchers answering more practical questions about ending hunger that are relevant to smallholder farmers? Many of the key reasons can be traced to the changing priorities of international agricultural-research funding.

    During the past four decades, funding provision for this type of research has been shifting towards the private sector, with more than half of funding now coming from #agribusinesses

    [...]

    At the same time, applied research involving working with smallholder farmers and their families doesn’t immediately boost an academic career. Many researchers — most notably those attached to the #CGIAR network of agricultural research centres around the world — do work with smallholder farmers. But in larger, research-intensive universities, small is becoming less desirable. Increasingly, university research-strategy teams want their academics to bid for larger grants — especially if a national research-evaluation system gives more credit to research income.

    Les revues de publication ont leur part de responsabilité dans cette #escroquerie...

    Publishers also bear some responsibility. Ceres2030’s co-director, Jaron Porciello, a data scientist at Cornell University in Ithaca, New York, told Nature that the subject matter for smallholder-farming research might not be considered sufficiently original, globally relevant or world-leading for journal publication. This lack of a sympathetic landing point in journals is something that all publishers must consider in the light of the Ceres2030 team’s findings.

    ... de même que les #pouvoirs_publics, partisans du « partenariat public-privé » dans les #universités ;

    National research agencies, too, need to listen, because they are the major funding source for researchers in universities. There’s a place for collaborating with big businesses, but achieving the SDG to end hunger will require an order of magnitude more research engagement with smallholders and their families. Their needs — and thus the route to ending hunger — have been neglected for too long.

  • Face masks: what the data say
    https://www.nature.com/articles/d41586-020-02801-8

    What does this imply for the ability of masks to impede COVID-19 transmission? The virus itself is only about 0.1 µm in diameter. But because viruses don’t leave the body on their own, a mask doesn’t need to block particles that small to be effective. More relevant are the pathogen-transporting droplets and aerosols, which range from about 0.2 µm to hundreds of micrometres across. (An average human hair has a diameter of about 80 µm.) The majority are 1–10 µm in diameter and can linger in the air a long time, says Jose-Luis Jimenez, an environmental chemist at the University of Colorado Boulder. “That is where the action is.”

    Scientists are still unsure which size of particle is most important in COVID-19 transmission. Some can’t even agree on the cut-off that should define aerosols. For the same reasons, scientists still don’t know the major form of transmission for influenza, which has been studied for much longer.

    Many believe that asymptomatic transmission is driving much of the COVID-19 pandemic, which would suggest that viruses aren’t typically riding out on coughs or sneezes. By this reasoning, aerosols could prove to be the most important transmission vehicle. So, it is worth looking at which masks can stop aerosols.

    #masque #covid #aérosolisation

    • All in the fabric

      Even well-fitting N95 respirators fall slightly short of their 95% rating in real-world use, actually filtering out around 90% of incoming aerosols down to 0.3 µm. And, according to unpublished research, N95 masks that don’t have exhalation valves — which expel unfiltered exhaled air — block a similar proportion of outgoing aerosols. Much less is known about surgical and cloth masks, says Kevin Fennelly, a pulmonologist at the US National Heart, Lung, and Blood Institute in Bethesda, Maryland.

      In a review9 of observational studies, an international research team estimates that surgical and comparable cloth masks are 67% effective in protecting the wearer.

      In unpublished work, Linsey Marr, an environmental engineer at Virginia Tech in Blacksburg, and her colleagues found that even a cotton T-shirt can block half of inhaled aerosols and almost 80% of exhaled aerosols measuring 2 µm across. Once you get to aerosols of 4–5 µm, almost any fabric can block more than 80% in both directions, she says.

      Multiple layers of fabric, she adds, are more effective, and the tighter the weave, the better. Another study10 found that masks with layers of different materials — such as cotton and silk — could catch aerosols more efficiently than those made from a single material.

      Benn worked with Danish engineers at her university to test their two-layered cloth mask design using the same criteria as for medical-grade ventilators. They found that their mask blocked only 11–19% of aerosols down to the 0.3 µm mark, according to Benn. But because most transmission is probably occurring through particles of at least 1 µm, according to Marr and Jimenez, the actual difference in effectiveness between N95 and other masks might not be huge.

      Eric Westman, a clinical researcher at Duke University School of Medicine in Durham, North Carolina, co-authored an August study11 that demonstrated a method for testing mask effectiveness. His team used lasers and smartphone cameras to compare how well 14 different cloth and surgical face coverings stopped droplets while a person spoke. “I was reassured that a lot of the masks we use did work,” he says, referring to the performance of cloth and surgical masks. But thin polyester-and-spandex neck gaiters — stretchable scarves that can be pulled up over the mouth and nose — seemed to actually reduce the size of droplets being released. “That could be worse than wearing nothing at all,” Westman says.

      Some scientists advise not making too much of the finding, which was based on just one person talking. Marr and her team were among the scientists who responded with experiments of their own, finding that neck gaiters blocked most large droplets. Marr says she is writing up her results for publication.

      “There’s a lot of information out there, but it’s confusing to put all the lines of evidence together,” says Angela Rasmussen, a virologist at Columbia University’s Mailman School of Public Health in New York City. “When it comes down to it, we still don’t know a lot.”

      Minding human minds

      Questions about masks go beyond biology, epidemiology and physics. Human behaviour is core to how well masks work in the real world. “I don’t want someone who is infected in a crowded area being confident while wearing one of these cloth coverings,” says Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota in Minneapolis.

      Perhaps fortunately, some evidence12 suggests that donning a face mask might drive the wearer and those around them to adhere better to other measures, such as social distancing. The masks remind them of shared responsibility, perhaps. But that requires that people wear them.

  • Cross-reactive memory T cells and herd immunity to #SARS-CoV-2 | Nature Reviews Immunology
    https://www.nature.com/articles/s41577-020-00460-4

    4 scénarios en rapport avec la présence d’une #immunité_croisée pré-existante et leurs répercussions sur l’#immunité de groupe :

    Le premier (diminution de la charge virale pulmonaire donc des formes sévères mais sans diminution de la charge des voies aériennes supérieures) n’accélèrerait pas l’immunité de groupe et pourrait même entraîner une majoration de la transmission du virus.

    Epidemiological implications

    Compared with a population including fewer individuals harbouring such memory, a population with more individuals with pre-existing cross-reactive CD4+ memory T cells would experience the following, all else being equal: (a) lower probabilities of hospitalizations and deaths per SARS-CoV-2 infection; and (b) no reduction, or potentially an increase, in viral spread. An increase could occur if the reduction in symptoms made infection harder to identify and trace and thus increased the frequency of undetected cases while not reducing infectiousness.

  • Fonte sans précédent de la calotte glaciaire
    Claude Gauvreau, Actualités UQAM, le 1er octobre 2020
    https://www.actualites.uqam.ca/2020/groenland-fonte-sans-precedent-calotte-glaciaire

    « Un tel scénario conduirait à une hausse de près d’un centimètre du niveau de la mer chaque année, ce qui entraînerait des répercussions dévastatrices pour les zones côtières de la planète », souligne la professeure du Département des sciences de la Terre et de l’atmosphère Anne de Vernal, qui fait partie de l’équipe de recherche. Celle-ci regroupe quelque 20 spécialistes dans les domaines de la modélisation climatique, de la géomorphologie, de la télédétection et de la paléoclimatologie, provenant principalement d’universités américaines.

    L’an dernier, la calotte glaciaire a perdu plus de 500 milliards de tonnes, un record, contribuant pour 40 % à la montée du niveau de la mer en 2019.

    Article original :

    Rate of mass loss from the Greenland Ice Sheet will exceed Holocene values this century
    Jason P. Briner, Joshua K. Cuzzone, Jessica A. Badgeley, Nicolás E. Young, Eric J. Steig, Mathieu Morlighem, Nicole-Jeanne Schlegel, Gregory J. Hakim, Joerg M. Schaefer, Jesse V. Johnson, Alia J. Lesnek, Elizabeth K. Thomas, Estelle Allan, Ole Bennike, Allison A. Cluett, Beata Csatho, Anne de Vernal, Jacob Downs, Eric Larour & Sophie Nowicki. Nature 586:70–74 (2020)
    https://www.nature.com/articles/s41586-020-2742-6

    On l’ajoutera à la quatrième compilation :
    https://seenthis.net/messages/818991

    #effondrement #collapsologie #catastrophe #fin_du_monde #it_has_begun #Anthropocène #capitalocène

  • Why Nature needs to cover politics now more than ever
    https://www.nature.com/articles/d41586-020-02797-1

    And just last week, in Japan, incoming Prime Minister Yoshihide Suga rejected the nomination of six academics, who have previously been critical of government science policy, to the Science Council of Japan. This is an independent organization meant to represent the voice of Japanese scientists. It is the first time that this has happened since prime ministers started approving nominations in 2004.

    Le premier ministre japonais, Yoshihide Suga, en guerre avec le monde intellectuel
    https://www.lemonde.fr/international/article/2020/10/06/le-premier-ministre-japonais-yoshihide-suga-en-guerre-avec-le-monde-intellec

  • #COVID research updates: Teenager spreads coronavirus on family holiday
    https://www.nature.com/articles/d41586-020-00502-w

    A 13-year-old girl gave the new #coronavirus to her grandparents and 9 other relatives who occupied the same holiday house for up to 3½ weeks, confirming that adolescents can seed #clusters of COVID-19 cases.

    https://www.cdc.gov/mmwr/volumes/69/wr/mm6940e2.htm?s_cid=mm6940e2_w

  • #COVID-19 : Le #masque pour faire face au virus | santé log
    https://www.santelog.com/actualites/covid-19-le-masque-pour-faire-face-au-virus

    Laisser tomber le masque augmenterait non seulement le risque d’infecter, mais aussi d’être infecté par le #coronavirus. Alors qu’après plus de 7 mois d’épidémie, certains commencent à douter de l’efficacité des mesures barrières, les principales preuves de la littérature scientifique doivent nous rappeler la nécessité de porter un masque de protection et de faire face au virus.