• COVID-19 isn’t just a cold

    This thread is long, and hard to read - not just because of the technical language, but because “it’s just a cold,” “the vaccine protects me,” and “at least our children are safe” are comforting fairy tales.

    I wish they were true.

    This virus is like measles and polio: a virus with long-term impact.

    Even a “mild” case in a vaccinated individual can lead to long-term issues which cause a measurable uptick in all-cause mortality in the first 6 months, and get progressively worse with time.

    SARS-CoV-2 is a systemic disease which has multiple avenues to induce long-term impairment, attacking the brain, heart, lungs, blood, testes, colon, liver, and lymph nodes, causing persistent symptoms in more than half of patients by six months out.

    The CoVHORT study, limited to non-hospitalized patients in Arizona - “mild” cases - found a 68% prevalence of 1 or more Covid symptom after 30 days, rising to 77% after 60 days. (We will explore an explanation later).

    https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0254347

    To prevent panic, @CDCgov has been using the term “mild” to describe any case of COVID-19 which does not require hospitalization.

    #LongCOVID, however, is anything but “mild”, as the replies to @ahandvanish’s thread make heartbreakingly clear.

    https://twitter.com/ahandvanish/status/1423017721822949376

    A University of Washington study found that 30% of Covid patients had reduced Health Related Quality of Life, with 8% of the patients limited in routine daily activities.

    https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2776560

    These patients are struggling with real physical issues.

    This Yale study demonstrated reduced aerobic capacity, oxygen extraction. and ventilatory efficiency in “mild” COVID patients even after recovery from their acute infection.

    https://journal.chestnet.org/article/S0012-3692(21)03635-7/abstract

    It’s also a vascular disease. A Columbia study found “significantly altered lipid metabolism” during acute disease, which “suggests a significant impact of SARS-CoV-2 infection on red blood cell structural membrane homeostasis.”

    https://pubs.acs.org/doi/full/10.1021/acs.jproteome.0c00606

    Oregon Health & Science University found that “symptomatic or asymptomatic SARS-CoV-2 infection is associated with increased risk of [fatal] cardiovascular outcomes and has causal effect on all-cause mortality.”

    https://www.medrxiv.org/content/10.1101/2021.12.27.21268448v1

    Let’s review: SARS-CoV-2 causes an increase in mortality and reduced aerobic capacity even after asymptomatic cases, and remains in the body months after the initial infection.

    No, it’s not “just a cold.”

    But we’re just getting started. It gets worse. Way worse.

    The virus appears to be able to cross the blood-brain barrier and cause significant neurological damage.

    The ability of the spike protein to cross the blood-brain barrier was demonstrated in mice at the University of Washington.

    https://pubmed.ncbi.nlm.nih.gov/33328624

    A joint study by Stanford and Germany’s Saarland University found inflammation in the brain, and “show[ed] that peripheral T cells infiltrate the parenchyma.”

    https://www.nature.com/articles/s41586-021-03710-0

    For context, the parenchyma is the functional tissue of the brain - your neurons and glial cells. It isn’t normally where T cells are:

    “In the brain of healthy individuals, T cells are only present sporadically in the parenchyma.”

    https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6751344

    The Stanford study also discovered microglia and astrocytes which displayed “features .. that have previously been reported in human neurodegenerative disease.”

    Post-mortem neuropathology in Hamburg, Germany found “Infiltration by cytotoxic T lymphocytes .. in the brainstem and cerebellum, [with] meningeal cytotoxic T lymphocyte infiltration seen in 79% [of] patients.”

    https://www.sciencedirect.com/science/article/pii/S1474442220303082#

    An autopsy of a 14-month-old at Brazil’s Federal University of Rio de Janeiro found that “The brain exhibited severe atrophy and neuronal loss.”

    https://www.thelancet.com/journals/lanam/article/PIIS2667-193X(21)00038-7/abstract

    The UK Biobank COVID-19 re-imaging study compared before and after images of “mild” cases, and found “pronounced reduction in grey matter” and an “increase of diffusion indices, a marker of tissue damage” in specific regions of the brain.

    https://www.medrxiv.org/content/10.1101/2021.06.11.21258690v3

    That seems to explain why there is evidence of persistent cognitive deficits in people who have recovered from SARS-CoV2 infection in Great Britain.

    https://www.thelancet.com/journals/eclinm/article/PIIS2589-5370(21)00324-2/fulltext

    Also worrisome are syncytia, where an infected cell extrudes its own spike protein and takes over its neighbors, fusing together to create a large multi-nucleus cell.

    Delta’s particular aptitude for this may partly explain its severity.

    https://www.news-medical.net/news/20211006/SARS-CoV-2-emerging-variants-display-enhanced-syncytia-formation.aspx

    And, yes, syncytia formation can happen in neurons. For our visual learners, here is video of syncytia and apoptosis (cell death) in a (bat) brain:

    https://twitter.com/nytimes/status/1429604323047133185

    Luckily, the University of Glasgow found that “Whilst Delta is optimised for fusion at the cell surface, Omicron .. achieves entry through endosomal fusion. This switch .. offers [an] explanation for [its] reduced syncytia formation.”

    https://www.gla.ac.uk/media/Media_829360_smxx.pdf

    If you’re interested in further understanding the host of neurological symptoms and the mechanisms underlying them, this Nature article is an excellent primer:

    https://www.nature.com/articles/d41586-021-01693-6

    Let’s review: SARS-CoV-2 can cross the blood-brain barrier, and even “mild” or asymptomatic cases can cause loss of neurons and persistent cognitive defects?

    That doesn’t sound “mild” to me; I like my brain.

    But it keeps getting worse.

    The brain isn’t the only organ affected: Testicular pathology has found evidence of “SARS-Cov-2 antigen in Leydig cells, Sertoli cells, spermatogonia, and fibroblasts” in post-morten examination.

    https://onlinelibrary.wiley.com/doi/10.1111/andr.13073

    A Duke pathology study in Singapore “detected SARS-CoV-2 .. in the colon, appendix, ileum, haemorrhoid, liver, gallbladder and lymph nodes .. suggesting widespread multiorgan involvement of the viral infection.”

    https://gut.bmj.com/content/gutjnl/early/2021/06/13/gutjnl-2021-324280.full.pdf#page1

    The same study found “evidence of residual virus in .. tissues during the convalescent phase, up to 6 months after recovery, in a non-postmortem setting,” suggesting that “a negative swab result might not necessarily indicate complete viral clearance from the body.”

    It also causes microclots: “Fibrin(ogen) amyloid microclots and platelet hyperactivation [were] observed in [Long COVID] patients,” in this work by Stellenbosch University of South Africa, which also explored potential treatments.

    https://www.researchsquare.com/article/rs-1205453/v1

    Let’s review - SARS-CoV2 attacks our veins, blood, heart, brain, testes, colon, appendix, liver, gallbladder and lymph nodes?

    No, it’s not “just a respiratory virus”.

    Not even close.

    There are also immunology implications:

    Johns Hopkins’ @fitterhappierAJ found that “CD95-mediated [T cell] differentiation and death may be advancing T cells to greater effector acquisition, fewer numbers, and immune dysregulation.”

    https://www.frontiersin.org/articles/10.3389/fimmu.2020.600405/full

    This Chinese military study of the initial Wuhan outbreak concluded that “T cell counts are reduced significantly in COVID-19 patients, and the surviving T cells appear functionally exhausted.”

    https://www.frontiersin.org/articles/10.3389/fimmu.2020.00827/full

    The study authors went on to warn, “Non-ICU patients with total T cells counts lower than 800/μL may still require urgent intervention, even in the immediate absence of more severe symptoms due to a high risk for further deterioration in condition.”

    Those warnings have since been proven by discovery of autoimmune features.

    This study of 177 Los Angeles healthcare workers found that all had persistent self-attacking antibodies at least 6 months after infection, regardless of illness severity.

    https://translational-medicine.biomedcentral.com/articles/10.1186/s12967-021-03184-8

    In the words of T-cell immunologist Dr. Leonardi (@fitterhappierAJ)

    https://twitter.com/fitterhappierAJ/status/1475227891034210314

    This Kaiser Permanente S.California study found that, although natural immunity provided substantial protection against reinfection, “Hospitalization was more common at suspected reinfection (11.4%) than initial infection (5.4%).”

    https://www.clinicalmicrobiologyandinfection.com/article/S1198-743X(21)00422-5/abstract

    In fact, remember those cytokine storms? It turns out that even that even severe COVID-19 may not be a viral pneumonia, but an autoimmune attack of the lung.

    https://twitter.com/DaveLeeERMD/status/1413816137570205697

    Let’s review - it’s autoimmune: SARS-CoV2 convinces our body to attack itself.

    That might explain why the Arizona study saw more symptoms after 60 days than at 30 days.

    It also means “natural immunity” isn’t something to count on.

    But if you’re counting on vaccination to feel safe, there’s even more bad news.

    A study of Israel healthcare workers found that “Most breakthrough cases were mild or asymptomatic, although 19% had persistent symptoms (>6 weeks).”

    https://www.nejm.org/doi/full/10.1056/NEJMoa2109072

    Perhaps the most terrifying study is from Oxford University, which examined the effects of vaccination on long COVID symptoms, because not only did it find that vaccination does not protect against Long Covid, but that Long Covid symptoms become more likely over time:

    In the words of the study authors, “vaccination does not appear to be protective against .. long-COVID features, arrhythmia, joint pain, type 2 diabetes, liver disease, sleep disorders, and mood and anxiety disorders."

    https://www.medrxiv.org/content/10.1101/2021.10.26.21265508v3

    “The narrow confidence intervals rule out the possibility that these negative findings are merely a result of lack of statistical power. The inclusion of death in a composite endpoint with these outcomes rules out survivorship bias as an explanation.”

    That finding contradicts the findings from the UK Zoe app study, which found that “the odds of having symptoms for 28 days or more after post-vaccination infection were approximately halved by having two vaccine doses.”

    https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(21)00460-6/fulltext

    However, the structural limitations of the Zoe study - discussed in detail by @dgurdasani1 in the linked thread - may explain why it is particularly susceptible to bias against detecting a progressive degenerative condition.

    https://twitter.com/dgurdasani1/status/1422802883632893952

    Let’s review: we’ve now shown that vaccination appears to offer no protection against the long-term autoimmune effects of COVID - which we know causes T-cells to attack the lungs, and can cause T-cells to enter the brain.

    Why are we letting this run wild?!

    You may think, at least our children are safe.

    They are not.

    The CDC is tracking incidence of a life-threatening multisystem inflammatory syndrome in children following an acute COVID-19 infection, with 5,973 cases as of November 30, 2021.

    https://covid.cdc.gov/covid-data-tracker/#mis-national-surveillance

    Children also suffer from Long Covid.

    “More than half [of pediatric patients] reported at least one persisting symptom even 120 days [after] COVID-19, with 42.6% impaired by these symptoms during daily activities.”

    https://www.medrxiv.org/content/10.1101/2021.01.23.21250375v1

    Focusing exclusively on pediatric deaths is vastly underselling the danger to children.

    Anybody telling you that SARS-CoV-2 is “just a cold” or “safe for children” is lying to you. They are ignoring the massive body of research that indicates that it is anything but.

    Since our vaccines don’t stop transmission, and don’t appear to stop long-term illness, a “vaccination only” strategy is not going to be sufficient to prevent mass disability.

    This isn’t something we want to expose our kids to.

    Let’s review: even for children and vaccinated people, a “mild” case of COVID causes symptoms that point to long-term autoimmune issues, potentially causing our own body to attack our brains, hearts, and lungs.

    Scared? Good.

    Now we’re ready to get to work.

    “This is the virus most Americans don’t know. We were born into a world where a virus was a thing you got over in a few weeks.” — @sgeekfemale, to whom I owe a “thank you” for her editing assistance on this thread.

    The viruses they know in Kolkota, Kinshasa, and Wuhan are different: dangerous, lethal beasts.

    Since 2020, the field has been leveled. Willing or no, we’ve rejoined the rest of the world. We are, all of us, vulnerable in the face of an unfamiliar threat.

    The first step is acknowledging the threat.

    That means acknowledging that our response has been woefully inadequate, and that is going to be uncomfortable.

    The thought that we could have prevented this, but didn’t, will feel unconscionable to some.

    The knowledge that we could start preventing this today, but haven’t, is unconscionable to me.

    https://twitter.com/IanRicksecker/status/1426584062827712512

    It’s time to quit pretending “it’s just a cold,” or that there is some magical law of viruses that will make it evolve to an acceptable level.

    There’s no such law of evolution, just wishful thinking, easily disproven by:

    Ebola. Smallpox. Marburg. Polio. Malaria.

    There are things we can do to reduce our individual risk, immediately.

    That starts with wearing a good mask - an N95 or better - and choosing to avoid things like indoor dining and capacity-crowd stadiums.

    https://twitter.com/LazarusLong13/status/1440398111445188618

    This isn’t a choice of “individual freedom” vs “public health”. It isn’t “authoritarian” to ask people to change their behavior in order to save lives.

    https://www.thehastingscenter.org/individual-freedom-or-public-health-a-false-choice-in-the-covid-e

    As Arnold @Schwarzenegger argued so convincingly in @TheAtlantic, it is our patriotic duty:

    “Generations of Americans made incredible sacrifices, and we’re going to throw fits about putting a mask over our mouth and nose?”

    https://www.theatlantic.com/ideas/archive/2021/08/schwarzenegger-schmuck-mask-vaccines/619746

    “Those who would sacrifice essential liberty for a little bit of temporary security deserve neither!”

    What is the essential liberty here?

    It is the liberty to be able to breathe clean air, to live our lives without infecting our families and risking disability.

    To get there, we need to listen to our epidemiologists and public health experts - the ones who have been trying to tell us this since the beginning:

    https://twitter.com/EpiEllie/status/1444088804961304581

    It is time — long past time — to give up on the lazy fantasy that we can let it become “endemic” and “uncontrolled” because it inconveniences us, because it is killing our political opponents, or because the virus will magically evolve to some “mild” state.

    It is time — long past time — to begin controlling this virus.

    It’s possible: Japan, New Zealand, and South Korea have done it.

    It saves lives:

    It’s even good for the economy:

    “Globally, economic contraction and growth closely mirror increases and decreases in COVID-19 cases... Public health strategies that reduce SARS-CoV-2 transmission also safeguard the economy.”

    https://bmcinfectdis.biomedcentral.com/articles/10.1186/s12879-021-06357-4

    It’s time.

    https://threadreaderapp.com/thread/1478611650760437765.html

    sur twitter :
    https://twitter.com/IanRicksecker/status/1478611650760437765

    #long-covid #covid-19 #coronavirus #covid_long #long_covid #séquelles #post-covid

  • Practical Indicators for Risk of Airborne Transmission in Shared Indoor Environments and Their Application to COVID-19 Outbreaks
    https://pubs.acs.org/doi/pdf/10.1021/acs.est.1c06531

    ABSTRACT: Some infectious diseases, including COVID-19, can undergo airborne transmission. This may happen at close proximity, but as time indoors increases, infections can occur in shared room air despite distancing. We propose two indicators of infection risk for this situation, that is, relative risk parameter (Hr) and risk parameter (H). They combine the key factors that control airborne disease transmission indoors: virus-containing aerosol generation rate, breathing flow rate, masking and its quality, ventilation and aerosol-removal rates, number of occupants, and duration of exposure. COVID-19 outbreaks show a clear trend that is consistent with airborne infection and enable recommendations to minimize transmission risk. Transmission in typical prepandemic indoor spaces is highly sensitive to mitigation efforts. Previous outbreaks of measles, influenza, and tuberculosis were also assessed. Measles outbreaks occur at much lower risk parameter values than COVID-19, while tuberculosis outbreaks are observed at higher risk parameter values. Because both diseases are accepted as airborne, the fact that #COVID-19 is less contagious than measles does not rule out airborne transmission. It is important that future outbreak reports include information on masking, ventilation and aerosol-removal rates, number of occupants, and duration of exposure, to investigate airborne transmission.

    #aérosols #masques #ventilation #mesures_de_mitigation

  • Relative Humidity Predicts Day-to-Day Variations in #COVID-19 Cases in the City of Buenos Aires | Environmental Science & Technology
    https://pubs.acs.org/doi/10.1021/acs.est.1c02711

    We found that humidity plays a prominent role in modulating the variation of COVID-19 positive cases through a negative-slope linear relationship, with an optimal lag of 9 days between the meteorological observation and the positive case report. This relationship is specific to winter months, when relative humidity predicts up to half of the variance in positive case count. Our results provide a tool to anticipate possible local surges in COVID-19 cases after events of low humidity. More generally, they add to accumulating evidence pointing to dry air as a facilitator of COVID-19 #transmission.

    #humidité

  • A Single Immunization with Spike-Functionalized Ferritin Vaccines Elicits Neutralizing Antibody Responses against SARS-CoV-2 in Mice | ACS Central Science
    https://pubs.acs.org/doi/10.1021/acscentsci.0c01405

    [...]

    #COVID-19 : Vers un #vaccin à dose unique et lyophilisé ? | santé log
    https://www.santelog.com/actualites/covid-19-vers-un-vaccin-dose-unique-et-lyophilise

    Certes ce candidat est beaucoup moins avancé, mais il promet des avantages incomparables au-delà d’une immunisation efficace : un schéma à injection unique, l’absence de contrainte de chaîne du froid pour le stockage, le transport et la distribution et un tarif bon marché. Développé par une équipe de virologues de l’Université de Stanford et présenté dans la revue ACS Central Science, le candidat basé sur des #nanoparticules de ferritine recouvertes de fragments de la protéine de pointe du coronavirus, vient de faire ses premières preuves chez la souris.

    [...]

    Si la prochaine étape reste la tenue d’essais cliniques, l’équipe travaille déjà également au développement d’un vaccin universel contre les #coronavirus (SRAS-CoV-1, MERS, SRAS-CoV-2 et les autres coronavirus qui pourraient émerger).

    #vaccination #vaccins #sars-cov2

  • Du bon usage des masques - Communiqué de l’Académie nationale de médecine 7 septembre 2020http://www.academie-medecine.fr/wp-content/uploads/2020/09/20.9.7-Du-bon-usage-masques.pdf

    dans l’espace public, les masques en tissu, lavables, doivent être préférés aux masques jetables pour d’évidentes raisons économiques et écologiques :
    • ils peuvent être lavés à la main ou en machine, avec un détergent, comme le linge de corps, la température de 60°C n’étant pas plus justifiée pour le lavage des masques que pour le lavage des mains ;
    • ils doivent être changés lorsqu’ils deviennent humides et ne jamais être portés plus d’une journée ;
    • ils sont réutilisables après chaque cycle de lavage - séchage tant que leurs qualités (maillage du tissu et intégrité des brides) ne sont pas altérées.
    De plus, l’Académie de médecine recommande :
    – que l’obligation du port du masque, systématiquement associée aux mesures de distanciation, soit instaurée dans tous les lieux publics, clos et ouverts, selon des règles faciles à comprendre, à appliquer et à contrôler ;
    – qu’une information claire et simplifiée sur l’usage des masques soit largement diffusée.

    On s’en doutait : le savon suffit à détruire l’enveloppe lipidique du virus, la température de lavage importe peu. Il n’est pas nécessaire d’accélérer l’usure des #masques par des lavages à 60°. Il aura fallu des mois pour que ce soit dit. Encore un exemple de la raréfaction du raisonnement logique que la pandémie révèle (et accroit). C’est un des aspects terrorisant de cette pandémie (post-vérité partout).

    • Je ne vois pas à quel moment ni comment « on s’en doutait ». Que de manière pratique, quasiment tout le monde finissait par mettre les masques avec le reste à la machine, parce que personne n’a de quoi faire 4 machines à 60° par semaine, ça oui, mais c’est juste une conséquence matérielle. Mais au niveau scientifique, logique, à un instant T, les chercheureuses pouvaient parfaitement avoir suffisamment de preuves pour dire que la chaleur niquait bien le truc, mais sans pour autant avoir assez de preuves pour le savon/les détergents. Et c’est pas chacun dans son coin qui pourrait faire ce « raisonnement logique » dans son coin, ça dépend des virus, faut faire des tests sérieux.

      Mais tant mieux, c’est super, si désormais il y a un consensus, qu’il y a assez de preuves, pour affirmer ça, et qu’effectivement ce que faisaient les gens par pure obligation matérielle, bah ça suffit réellement au niveau santé.

    • Le savon dissout les graisses. Sans l’enveloppe lipidique qui le protège le brin d’arn du coronavirus est fichu. Pour ma part, depuis longtemps, je fais mariner dans de l’eau très savonneuse un bon moment, puis je rince. Si je lave avec d’autre tissus en machine, je surdose le savon (pour calmer l’anxiété).
      Les recommandations sur le séchage m’ont toujours paru débiles. Il faudrait que le masque sèche dans un endroit très infecté (une chambre de covidé ?) pour qu’il soit contaminé.
      Voir par exemple
      https://stop-postillons.fr/#en-vie-reelle
      Dont les données sont issues d’une étude Lancet d’avril dernier
      https://ars.els-cdn.com/content/image/1-s2.0-S2666524720300033-mmc1.pdf

      Que l’académie de médecine gauloise finisse par le dire des mois après n’est qu’un indice de plus que tout est fait pour que l’on n’y comprenne rien, pour déposséder les premiers concernés. La liberté est pour la police. La logique, pour personne.

    • Je vois aussi un autre point en contradiction avec les recommandations précédentes, celui de favoriser désormais l’usage du masque en tissu (sur les affiches en mai on voyait encore « utilisez un masque jetable »). Est-ce que d’un point de vue scientifique ça se tient ? Beaucoup de masques en tissu fait-maison m’ont l’air d’être des vraies passoires sans compter que la plupart du temps ils sont bien moins confortables que leurs homologues jetables, surtout par forte chaleur, ce qui n’incite pas à leur usage.

    • Concrètement, avec un virus qui contamine essentiellement par aérosolisation, c’est une recommandation de merde.

      Pour respecter les arrêtés stupides de port du masque dans la rue, oui, le masque en tissu fait parfaitement l’affaire  : il te protège bien du seul risque, celui de la prune à 135€.

      À la limite, pour les courses dans un magasin pas trop peuplé où tu peux éviter les autres… mais bon, sachant que beaucoup de gens continuent à faire les rebelles en sortant le pif ou en baissant le masque à tout bout de champ, dès que c’est fermé, c’est au moins le chirurgical.

      Mais pour les lieux où les gens macèrent ensembles pendant des plombes comme au boulot, dans les bureaux en open space, les réunions, les salles de classes, même le chirurgical est un peu léger. En gros, le protocole aurait dû interdire ce genre de situations. Surtout que beaucoup de gens ont des masques insuffisants et/ou mal ajustés (tissu trop fin ou à maillage trop lâche, mauvaise forme, coutures mal placées, etc.). Dès qu’il est humide, le chirurgical est à benner. Pour un orateur — qui doit un peu pousser sa voix pour se faire entendre — ça peut aller assez vite. Donc en population dense en milieu confiné (ce qui ne devrait pas être autorisé, je le répète), ce serait plutôt FFP2 ou équivalent, sachant que sur les visages fins ou maigres, les masques ne s’adaptent pas bien…

    • Aerosol Filtration Efficiency of Common Fabrics Used in Respiratory Cloth Masks
      https://pubs.acs.org/doi/10.1021/acsnano.0c03252

      The emergence of a pandemic affecting the respiratory system can result in a significant demand for face masks. This includes the use of cloth masks by large sections of the public, as can be seen during the current global spread of COVID-19. However, there is limited knowledge available on the performance of various commonly available fabrics used in cloth masks. Importantly, there is a need to evaluate filtration efficiencies as a function of aerosol particulate sizes in the 10 nm to 10 μm range, which is particularly relevant for respiratory virus transmission. We have carried out these studies for several common fabrics including cotton, silk, chiffon, flannel, various synthetics, and their combinations. Although the filtration efficiencies for various fabrics when a single layer was used ranged from 5 to 80% and 5 to 95% for particle sizes of <300 nm and >300 nm, respectively, the efficiencies improved when multiple layers were used and when using a specific combination of different fabrics. Filtration efficiencies of the hybrids (such as cotton–silk, cotton–chiffon, cotton–flannel) was >80% (for particles <300 nm) and >90% (for particles >300 nm). We speculate that the enhanced performance of the hybrids is likely due to the combined effect of mechanical and electrostatic-based filtration. Cotton, the most widely used material for cloth masks performs better at higher weave densities (i.e., thread count) and can make a significant difference in filtration efficiencies. Our studies also imply that gaps (as caused by an improper fit of the mask) can result in over a 60% decrease in the filtration efficiency, implying the need for future cloth mask design studies to take into account issues of “fit” and leakage, while allowing the exhaled air to vent efficiently. Overall, we find that combinations of various commonly available fabrics used in cloth masks can potentially provide significant protection against the transmission of aerosol particles.

      Encore ne s’agit-il dans cet article que de masques deux couches. D’autres préconisent 3 couches, avec des caractéristiques complémentaires.

      Le mot masque recouvre une gamme plus qu’hétéroclite d’objets, dont de nombreux ersatzs.
      Que le gouvernement se contre foute de la santé publique en édictant aucune recommandation étayée, aucune norme, en ne contribuant pas à la création de chaines de production de masques ad hoc, de là à croire que « les » masques en tissu ne protègent pas....
      Ce qui est une fois de plus sidérant - par delà l’irresponsabilité nuisible du gvt, les profit des boites - c’est que tout se passe comme si le nombre de scientifiques, de techniciens, d’ingénieurs, de fabricants, de soignants en tous genres, de journalistes scientifiques susceptibles de compiler des données, d’expérimenter pour contribuer à la définition et à la fabrication de bons équipements de protection personnelle ne servait à rien. Pourquoi a-t-on financé la formation de ces professionnels ? Pourquoi les paye-t-on ? Qu’est-ce qui interdit que l’intelligence collective, les savoirs répondent à des besoins ? Faut il en conclure à une expansion illimitée de la sphère des bullshit jobs ? Insondables mystères de l’anti-production capitaliste.

  • Masque grand public
    #PLAYMOBIL, avril 2020
    https://company.playmobil.com/Company/fr-FR/Playmobil-mask

    4.99 Euros

    Le porteur du masque doit y insérer une matière absorbante de type mouchoir en papier servant de filtre avant chaque utilisation.
    D’autres éléments absorbants peuvent être utilisés en tant que filtres (tous types mouchoirs en papier). Le masque ne doit pas être utilisé sans filtre.
    Pour des raisons d’hygiène, ce masque peut être utilisé uniquement lorsqu’il est propre et par une seule personne.
    Lorsque vous portez le masque, assurez-vous que le nez et la bouche soient couverts. Un fil élastique est utilisé pour le maintenir en place afin qu’il ne glisse pas, même avec des mouvements rapides (voir image).
    Tous les gestes barrières doivent être respectés lors du port du masque, comme par exemple garder une distance de sécurité de 1,5m minimum.
    Nettoyage : Le masque doit être entièrement lavé avec de l’eau chaude et du savon liquide après une utilisation de 10 heures. Il faut retirer le filtre avant le nettoyage.N’oubliez pas d’insérer un nouveau filtre lors de la prochaine utilisation.

    #coronavirus #masques

    • De nouveau, quoi qu’en dise tel ou tel médecin des armées avec ses serviettes de table sur YT, tel locuteur avec ses filtres à café, le meilleur des filtres disponibles, si on excepte les sacs d’aspirateurs (trop peu respirants), ce sont les #lingettes_dépoussiérantes_antistatiques 100% polyester (sans produit chimique ajouté, bannir absolument océdar, etc.). Il y a des explications techniques précises sur la manière dont elles filtrent une partie des particules en les piégeant (pas seulement en raison de leur densité). Retenons l’idée simple : "le polyester « s’électrise » rapidement, ce qui va faire que ce qui va passer près du filtre va être attiré vers lui", et cessons peut-être d’ajouter du bruit au bruit sur les matériaux de filtration qui sont indispensables dans les masques, jetables ou pas. Sans omettre de bucher sur les précautions d’emploi (avant, pendant, après), et de rechercher/fabriquer des modèles qui soient le mieux ajustés possibles (fuite d’air des deux cotés du nez fréquenté).

      Après on peu regarder tout ce qu’on veut. À quel point l’aérosol est-il contaminant (celui est vrais dans la chambre et les WC d’un malade hospitalisé) ? et si la réponse est oui, faut il vraiment trouver de la soie sauvage pour en ajouter deux couches, comme cela est indiqué

      Masques et mesures de protection
      • Une étude qui étudie différents tissus et leur capacité de filtration pour les gouttelettes et aérosols.
      Pour les gouttelettes, le coton 600TPI a une bonne capacité de filtration ; pour les particules très fines, la soie naturelle, la flanelle et la mousseline de coton offrent une bonne protection par filtrage électrostatique
      La combinaison de ces deux approches par superposition de ces deux type de matériaux semblent fournir de bons résultats. Les chercheurs/ses recommandent une couche de coton à forte densité de fibre accolée à 2 couches de soie naturelle ou de mousseline par exemple.
      La bonne adaptation du masque au visage est un paramètre déterminant, un écart peut diminuer de l’ordre de 60 % le niveau de protection offert par le masque.

      https://pubs.acs.org/doi/pdf/10.1021/acsnano.0c03252

      Une info parmi d’autre en provenance de cette très bonne revue de presse scientifique, technique et média, que Jessica Guibert, médecin généraliste au village 2 santé à Echirolles, élabore et partage
      https://pratiques.fr/Suivi-de-la-crise-liee-au-Covid19

      #filtration

  • “Researchers find bug in #Python script may have affected hundreds of [scientific] studies [in biology]”

    https://arstechnica.com/information-technology/2019/10/chemists-discover-cross-platform-python-scripts-not-so-cross-platform

    #Willoughby_Hoye” scripts used OS call that caused incorrect measurements on some platforms.

    The paper showing the problem: https://pubs.acs.org/doi/full/10.1021/acs.orglett.9b03216

    The original paper with the bug: https://www.nature.com/articles/nprot.2014.042

    #bug #science

  • Un #fromage vieux de 3 200 ans découvert dans une tombe égyptienne
    https://www.francetvinfo.fr/sciences/archeologie/un-fromage-vieux-de-3200-ans-decouvert-dans-une-tombe-egyptienne_290007

    Un fromage vieux de 3 200 ans a été découvert dans l’ancienne capitale de l’#Égypte antique, Memphis, selon une étude relayée vendredi 17 août par le HuffPost. Une équipe scientifique a retrouvé des pots cassés remplis d’une mystérieuse substance blanche dans la tombe de Phtames, l’ancien maire de #Memphis.

    #archéologie #alimentation #égyptologie

    Lien vers l’article du Anatical chemistry : https://pubs.acs.org/doi/abs/10.1021/acs.analchem.8b02535