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Suggests that had the govt really 'followed the science' the first kids back in to school would have been those that are best able to moderate their tendency to shout/sing - older kids. And yet we started with the very opposite!

Does anyone else wash everything they buy in the shops now, wherever possible? I've taken the contact transmission risk to heart since I can easily control all the other risks, but not sure if going too far. unpacking the shopping & putting it away can easily take as long as buying it all did

It’s not common to contract Covid-19 from a contaminated surface, scientists say

I've heard this a few times, and I'm not doubting it, but I am really interested to understand why this is, because other respiratory viruses - like rhinoviruses - tend to transmit very effectively via hand-to-surface-to-face contact. And the coronavirus seems to remain active on hard surfaces for longer than rhinoviruses do.

This WSJ article is a really good summary of the scientific understanding but they don't give a source for this particular claim.

Could it simply be because prior to lockdowns, the drive for fastidious hand and surface hygiene actually trampled out much of this spread, while at the same time social distancing guidance hadn't been pushed as hard yet? Have we just been good at staying away from places that tend to have lots of high-touch surfaces? These are guesses. But I'd be curious to read more about it!

Nothing particularly new, but seems like a reasonable summary of current understanding.

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If people are still asking this question, they have been living under a rock.

This and other stories in the next issue of "Duh" magazine.

Indoors with people and no PPE = death. Out doors with PPE = life.

That's what the science is telling us. Churches, bars, schools, visiting friends and relatives kills. Outside, away from people, wearing masks: relatively safe.

Explains all the outbreaks in churches and bars while there have been almost no cases from the protests.

Not a surprise to me but the UK (English) government either doesn't know this or doesn't care as currently they want to reduce social distancing to 1m in order to help pubs and restaurants reopen.

Someone passing me 1m away outdoors on a pavement is probably little or zero risk.

Someone passing me 1m away in a supermarket aisle is probably little risk.

Spending 15mins in a bus or train with people 1m away is a higher risk.

Spending 1-2hrs in a restaurant or crowded pub with people 1m (or less) aways probably an even higher risk.

​

Southern US states where social distancing has basically gone with little mask wearing have shown a spike in Covid-19 cases amongst the young. https://www.huffingtonpost.co.uk/entry/younger-people-testing-positive-covid-19_n_5ef0bf99c5b639909d576089?ri18n=true

Imo this article is poorly written. The author contradicts almost every point made in the beginning paragraphs by stating the exact opposite afterward. It's as if the author wrote a catchy headline and then just copied and pasted wording from a bunch of different articles written since February to generate content for clicks with no regard for what is being presented. Sad.

From article:

"It’s not common to contract Covid-19 from a contaminated surface, scientists say."

Same article:

"High-touch surfaces like doorknobs are a risk..."

From article:

"And fleeting encounters with people outdoors are unlikely to spread the coronavirus."

Instead, the major culprit is close-up, person-to-person interactions for extended periods. Crowded events, poorly ventilated areas and places where people are talking loudly—or singing.. maximize the risk."

Same article:

"One important factor in transmission is that seemingly benign activities like speaking and breathing produce respiratory bits of varying sizes that can disperse along air currents and potentially infect people nearby."

Just two examples but there are many contradictions and statements not backed up by actual sources. "Some scientist say" ... ya OK. Very official and trustworthy. Thanks but no thanks.

When I take the bike uptown, I see a lot of this. Restaurants, bars,etc. Our cases are going to go up. I only have to watch the news to get the numbers, I know which way it's going

Wear a face shield with your mask! It’s like having a portable, wearable plexiglas barrier on you at all times.

It's important to move away from mass hysteria to targeted measures. To do that we need to quantify what's important to avoid (prolonged, close-quarters contact without masks) and what isn't (fleeting contact outdoors).

Based on the number of "oh my god I saw someone cycling outdoors without a mask" responses I'd say this is a message worth spreading.

Well duh.

Really? Omg, we didn't know that.

Rest of article:

“Changing policies

Based on this emerging picture of contagion, some policies are changing. The standard procedure for someone who tests positive is to quarantine at home. Some cities are providing free temporary housing and social services where people who are infected can stay on a voluntary basis, to avoid transmitting the virus to family members.

The CDC recently urged Americans to keep wearing masks and maintaining a distance from others as states reopen. “The more closely you interact with others, the longer the interaction lasts, the greater the number of people involved in the interaction, the higher the risk of Covid-19 spread,” said Jay Butler, the CDC’s Covid-19 response incident manager.

If the number of Covid-19 cases starts to rise dramatically as states reopen, “more extensive mitigation efforts such as what were implemented back in March may be needed again,” a decision that would be made locally, he said.

CDC guidelines for employers whose workers are returning include requiring masks, limiting use of public transit and elevators to reduce exposure, and prohibiting hugs, handshakes and fist-bumps. The agency also suggested replacing communal snacks, water coolers and coffee pots with prepacked, single-serve items, and erecting plastic partitions between desks closer than 6 feet apart.

Current CDC workplace guidelines don’t talk about distribution of aerosols, or small particles, in a room, said Lisa Brosseau, a respiratory-protection consultant for the University of Minnesota’s Center for Infectious Disease Research and Policy.

“Aerosol transmission is a scary thing,” she said. “That’s an exposure that’s hard to manage and it’s invisible.” Ensuring infected individuals stay home is important, she said, but that can be difficult due to testing constraints. So additional protocols to interrupt spread, like social distancing in workspaces and providing N95 respirators or other personal protective equipment, might be necessary as well, she said.

Some scientists say while aerosol transmission does occur, it doesn’t explain most infections. In addition, the virus doesn’t appear to spread widely through the air.

“If this were transmitted mainly like measles or tuberculosis, where infectious virus lingered in the airspace for a long time, or spread across large airspaces or through air-handling systems, I think you would be seeing a lot more people infected,” said the CDC’s Dr. Brooks.

Sampling the air in high-traffic areas regularly could help employers figure out who needs to get tested, said Donald Milton, professor of environmental and occupational health at the University of Maryland School of Public Health.

“Let’s say you detect the virus during lunchtime on Monday in a dining hall,” he said. “You could then reach out to people who were there during that time telling them that they need to get tested.”

Erin Bromage, a University of Massachusetts Dartmouth associate professor of biology, has been fielding questions from businesses, court systems and even therapists after a blog post he wrote titled “The Risks—Know Them—Avoid Them” went viral.

Courts are trying to figure out how to reconvene safely given that juries normally sit close together, with attorneys speaking to them up close, Dr. Bromage said. Therapists want to be able to hold in-person counseling sessions again. And businesses are trying to figure out what types of cleaning and disease-prevention methods in which to invest most heavily.

He advises that while wiping down surfaces and putting in hand-sanitizer stations in workplaces is good, the bigger risks are close-range face-to-face interactions, and having lots of people in an enclosed space for long periods. High-touch surfaces like doorknobs are a risk, but the virus degrades quickly so other surfaces like cardboard boxes are less worrisome, he said. “Surfaces and cleaning are important, but we shouldn’t be spending half of our budget on it when they may be having only a smaller effect,” he said.

Drugmaker Eli Lilly & Co. has a medical advisory panel that’s reading the latest literature on viral transmission, which it is using to develop recommendations for bringing back the company’s own workers safely.

To go into production facilities, some of which are in operation now, scientists must don multiple layers of personal protective equipment, including gloves, masks, goggles and coveralls. That’s not abnormal for drug-development settings, said Lilly Chief Scientific Officer Daniel Skovronsky. “The air is extensively filtered. There’s lots of protection,” he said.

The places he worries about are the break rooms, locker rooms and security checkpoints, where people interact. Those are spaces where the company has instituted social-distancing measures by staggering the times they are open and how many people can be there at once. Only a few cafeterias are open, and those that are have socially distanced seating. In bathrooms, only half the stalls are available to cut down on the number of people.

“We’ll never be more open than state guidelines,” Dr. Skovronsky said, but “we’re often finding ourselves being more restrictive because we’re following the numbers.”

Article:

“How Exactly Do You Catch Covid-19? There Is a Growing Consensus

Surface contamination and fleeting encounters are less of a worry than close-up, person-to-person interactions for extended periods

By , and Updated June 16, 2020 10:39 am ET Six months into the coronavirus crisis, there’s a growing consensus about a central question: How do people become infected?

It’s not common to contract Covid-19 from a contaminated surface, scientists say. And fleeting encounters with people outdoors are unlikely to spread the coronavirus.

Instead, the major culprit is close-up, person-to-person interactions for extended periods. Crowded events, poorly ventilated areas and places where people are talking loudly—or singing, in one famous case—maximize the risk.

These emerging findings are helping businesses and governments devise reopening strategies to protect public health while getting economies going again. That includes tactics like installing plexiglass barriers, requiring people to wear masks in stores and other venues, using good ventilation systems and keeping windows open when possible.

Two recent large studies showed that wide-scale lockdowns—stay-at-home orders, bans on large gatherings and business closures—prevented millions of infections and deaths around the world. Now, with more knowledge in hand, cities and states can deploy targeted interventions to keep the virus from taking off again, scientists and public-health experts said.

That means better protections for nursing-home residents and multigenerational families living in crowded conditions, they said. It also means stressing physical distancing and masks, and reducing the number of gatherings in enclosed spaces.

“We should not be thinking of a lockdown, but of ways to increase physical distance,” said Tom Frieden, chief executive of Resolve to Save Lives, a nonprofit public-health initiative. “This can include allowing outside activities, allowing walking or cycling to an office with people all physically distant, curbside pickup from stores, and other innovative methods that can facilitate resumption of economic activity without a rekindling of the outbreak.”

The group’s reopening recommendations include widespread testing, contact tracing and isolation of people who are infected or exposed.

One important factor in transmission is that seemingly benign activities like speaking and breathing produce respiratory bits of varying sizes that can disperse along air currents and potentially infect people nearby.

Health agencies have so far identified respiratory-droplet contact as the major mode of Covid-19 transmission. These large fluid droplets can transfer virus from one person to another if they land on the eyes, nose or mouth. But they tend to fall to the ground or on other surfaces pretty quickly.

Some researchers say the new coronavirus can also be transmitted through aerosols, or minuscule droplets that float in the air longer than large droplets. These aerosols can be directly inhaled.

That’s what may have happened at a restaurant in Guangzhou, China, where an infected diner who was not yet ill transmitted the virus to five others sitting at adjacent tables. Ventilation in the space was poor, with exhaust fans turned off, according to one study looking at conditions in the restaurant.

Aerosolized virus from the patient’s breathing or speaking could have built up in the air over time and strong airflow from an air-conditioning unit on the wall may have helped recirculate the particles in the air, according to authors of the study, which hasn’t yet been peer-reviewed.

Sufficient ventilation in the places people visit and work is very important, said Yuguo Li, one of the authors and an engineering professor at the University of Hong Kong. Proper ventilation—such as forcing air toward the ceiling and pumping it outside, or bringing fresh air into a room—dilutes the amount of virus in a space, lowering the risk of infection.

Another factor is prolonged exposure. That’s generally defined as 15 minutes or more of unprotected contact with someone less than 6 feet away, said John Brooks, the Centers for Disease Control and Prevention’s chief medical officer for the Covid-19 response. But that is only a rule of thumb, he cautioned. It could take much less time with a sneeze in the face or other intimate contact where a lot of respiratory droplets are emitted, he said.

Superspreaders

At a March 10 church choir practice in Washington state, 87% of attendees were infected, said Lea Hamner, an epidemiologist with the Skagit County public-health department and lead author of a study on an investigation that warned about the potential for “superspreader” events, in which one or a small number of people infect many others.

Members of the choir changed places four times during the 2½-hour practice, were tightly packed in a confined space and were mostly older and therefore more vulnerable to illness, she said. All told, 53 of 61 attendees at the practice were infected, including at least one person who had symptoms. Two died.

Several factors conspired, Ms. Hamner said. When singing, people can emit many large and small respiratory particles. Singers also breathe deeply, increasing the chance they will inhale infectious particles.

Similar transmission dynamics could be at play in other settings where heavy breathing and loud talking are common over extended periods, like gyms, musical or theater performances, conferences, weddings and birthday parties. Of 61 clusters of cases in Japan between Jan. 15 and April 4, many involved heavy breathing in close proximity, such as karaoke parties, cheering at clubs, talking in bars and exercising in gyms, according to a recent study in the journal Emerging Infectious Diseases.

The so-called attack rate—the percentage of people who were infected in a specific place or time—can be very high in crowded events, homes and other spaces where lots of people are in close, prolonged contact.

An estimated 10% of people with Covid-19 are responsible for about 80% of transmissions, according to a study published recently in Wellcome Open Research. Some people with the virus may have a higher viral load, or produce more droplets when they breathe or speak, or be in a confined space with many people and bad ventilation when they’re at their most infectious point in their illness, said Jamie Lloyd-Smith, a University of California, Los Angeles professor who studies the ecology of infectious diseases.

But overall, “the risk of a given infected person transmitting to people is pretty low,” said Scott Dowell, a deputy director overseeing the Bill & Melinda Gates Foundation’s Covid-19 response. “For every superspreading event you have a lot of times when nobody gets infected.”

The attack rate for Covid-19 in households ranges between 4.6% and 19.3%, according to several studies. It was higher for spouses, at 27.8%, than for other household members, at 17.3%, in one study in China.

Rosanna Diaz lives in a three-bedroom apartment in New York City with five other family members. The 37-year-old stay-at-home mother was hospitalized with a stroke on April 18 that her doctors attributed to Covid-19, and was still coughing when she went home two days later.

She pushed to get home quickly, she said, because her 4-year-old son has autism and needed her. She kept her distance from family members, covered her mouth when coughing and washed her hands frequently. No one else in the apartment has fallen ill, she said. “Nobody went near me when I was sick,” she said.

Being outside is generally safer, experts say, because viral particles dilute more quickly. But small and large droplets pose a risk even outdoors, when people are in close, prolonged contact, said Linsey Marr, a Virginia Tech environmental engineering professor who studies airborne transmission of viruses.

No one knows for sure how much virus it takes for someone to become infected, but recent studies offer some clues. In one small study published recently in the journal Nature, researchers were unable to culture live coronavirus if a patient’s throat swab or milliliter of sputum contained less than one million copies of viral RNA.

Based on our experiment, I would assume that something above that number would be required for infectivity,” said Clemens Wendtner, one of the study’s lead authors and head of the department of infectious diseases and tropical medicine at München Klinik Schwabing, a teaching hospital at the Ludwig Maximilian University of Munich.

He and his colleagues found samples from contagious patients with virus levels up to 1,000 times that, which could help explain why the virus is so infectious in the right conditions: It may take much lower levels of virus than what’s found in a sick patient to infect someone else.”

Part 2 in next comment. It was too long for one comment.

Paywall

en gros : les paranos du gel hydroalcoolique qui ne portent pas de masque, vous avez tout faux.
Depuis le début ce consensus a toujours été le plus fort dans le monde scientifique, c'est juste que les médias ne savaient pas lire les études ("le virus reste 2jours sur des surfaces" -> non, ce sont des traces, etc ... )

Merci pour le partage, je trouve qu'on ne parle pas du tout assez de ce fait que je vois de plus en plus depuis quelques semaines. La contamination se fait en "chargeant" l'air, cela rend certaines interdictions overkill (typiquement les événements en extérieurs pas trop dense ) et ça montre également que certaines activités pourraient ne tout simplement pas reprendre tant qu'un vaccin n'est pas trouvé (ex :les boîtes de nuit ). Ça expliquerait aussi pourquoi la saisonnalité et l'arrivée de l'été freine le virus, tout simplement parce que les gens fo't plus d'activités en extérieur et aérent plus leur environnement

Le covid c’est so first-half-of-2020

Il n’y a pas un rapport du conseil scientifique covid ou des autorités qui confirment toussa? J’aimerais bien de le montrer à mon l’employeur qui nous fait obliger de revenir travailler sur site au lieu de télétravailler

Comment attrape-t-on exactement le Covid-19 ?

Un consensus grandissant : La contamination de surface et les rencontres fugitives sont moins préoccupantes que les interactions de personne à personne de près pendant de longues périodes

Six mois après le début de la crise des coronavirus, un consensus croissant se dégage sur une question centrale : Comment les gens sont-ils infectés ?

Il n'est pas courant de contracter le Covid-19 à partir d'une surface contaminée, disent les scientifiques. Et les rencontres éphémères avec des personnes à l'extérieur ont peu de chances de propager le coronavirus.

Au lieu de cela, le principal coupable est la proximité, les interactions de personne à personne pendant de longues périodes. Les événements à forte affluence, les zones mal ventilées et les endroits où les gens parlent fort - ou chantent, dans un cas célèbre - maximisent le risque.

Ces nouvelles découvertes aident les entreprises et les gouvernements à concevoir des stratégies de réouverture pour protéger la santé publique tout en relançant l'économie. Cela inclut des tactiques comme l'installation de barrières en plexiglas, l'obligation de porter des masques dans les magasins et autres lieux, l'utilisation de bons systèmes de ventilation et le maintien des fenêtres ouvertes lorsque cela est possible.

Deux grandes études récentes ont montré que des mesures de confinement à grande échelle - interdiction de séjour à domicile, interdiction de grands rassemblements et fermetures d'entreprises - ont permis d'éviter des millions d'infections et de décès dans le monde. Maintenant que nous disposons de plus de connaissances, les villes et les États peuvent déployer des interventions ciblées pour empêcher le virus de se propager à nouveau, ont déclaré les scientifiques et les experts de la santé publique.

Cela signifie de meilleures protections pour les résidents des maisons de retraite et les familles multigénérationnelles qui vivent dans des conditions de surpopulation, ont-ils déclaré. Cela signifie également qu'il faut mettre l'accent sur l'éloignement physique et les masques, et réduire le nombre de rassemblements dans des espaces clos.

"Nous ne devrions pas penser à un verrouillage, mais à des moyens d'augmenter la distance physique", a déclaré Tom Frieden, directeur général de Resolve to Save Lives, une initiative de santé publique à but non lucratif. "Il peut s'agir d'autoriser les activités extérieures, de permettre de se rendre à pied ou à vélo à un bureau avec des personnes toutes physiquement éloignées, d'assurer la collecte en bordure de trottoir dans les magasins, et d'autres méthodes innovantes qui peuvent faciliter la reprise de l'activité économique sans relancer l'épidémie".

Les recommandations de réouverture du groupe comprennent la généralisation des tests, la recherche des contacts et l'isolement des personnes infectées ou exposées.

https://i.imgur.com/tvnzdVi.png

Un facteur important dans la transmission est que des activités apparemment bénignes comme parler et respirer produisent des bouts respiratoires de tailles variables qui peuvent se disperser le long des courants d'air et potentiellement infecter les personnes à proximité.

Les agences de santé ont jusqu'à présent identifié le contact entre les gouttelettes respiratoires comme le principal mode de transmission de Covid-19. Ces grosses gouttelettes de liquide peuvent transférer le virus d'une personne à une autre si elles atterrissent sur les yeux, le nez ou la bouche. Mais ils ont tendance à tomber sur le sol ou sur d'autres surfaces assez rapidement.

Certains chercheurs affirment que le nouveau coronavirus peut également être transmis par des aérosols, ou de minuscules gouttelettes qui flottent dans l'air plus longtemps que les grosses gouttelettes. Ces aérosols peuvent être directement inhalés.

C'est ce qui a pu se produire dans un restaurant de Guangzhou, en Chine, où un dîneur infecté qui n'était pas encore malade a transmis le virus à cinq autres personnes assises à des tables voisines. La ventilation de l'espace était médiocre, les ventilateurs d'extraction étant éteints, selon une étude portant sur les conditions dans le restaurant.

Le virus en aérosol provenant de la respiration ou de la parole du patient pourrait s'être accumulé dans l'air au fil du temps et un fort débit d'air provenant d'une unité de climatisation murale pourrait avoir aidé à faire recirculer les particules dans l'air, selon les auteurs de l'étude, qui n'a pas encore été examinée par des pairs.

Une ventilation suffisante dans les lieux que les gens visitent et où ils travaillent est très importante, a déclaré Yuguo Li, l'un des auteurs et professeur d'ingénierie à l'université de Hong Kong. Une ventilation adéquate - par exemple en poussant l'air vers le plafond et en le pompant à l'extérieur, ou en faisant entrer de l'air frais dans une pièce - permet de diluer la quantité de virus dans un espace, ce qui réduit le risque d'infection.

Un autre facteur est l'exposition prolongée. C'est généralement défini comme 15 minutes ou plus de contact non protégé avec quelqu'un à moins d'un mètre cinquante, a déclaré John Brooks, le médecin en chef des Centers for Disease Control and Prevention pour la réponse au Covid-19. Mais ce n'est qu'une règle empirique, a-t-il averti. Cela pourrait prendre beaucoup moins de temps avec un éternuement au visage ou un autre contact intime où beaucoup de gouttelettes respiratoires sont émises, a-t-il dit. Les super-épandeurs

Lors d'une répétition de la chorale de l'église le 10 mars dernier dans l'État de Washington, 87 % des participants ont été infectés, a déclaré Lea Hamner, épidémiologiste du département de santé publique du comté de Skagit et auteur principal d'une étude sur une enquête qui a mis en garde contre le risque d'événements de "super propagation", dans lesquels une ou un petit nombre de personnes infecte beaucoup d'autres.

Les membres de la chorale ont changé de place quatre fois au cours de la répétition de 2½, étaient entassés dans un espace confiné et étaient pour la plupart plus âgés et donc plus vulnérables aux maladies, a-t-elle déclaré. Au total, 53 des 61 participants au cabinet ont été infectés, dont au moins une personne qui présentait des symptômes. Deux sont morts.

Plusieurs facteurs ont concouru, a déclaré Mme Hamner. En chantant, les gens peuvent émettre de nombreuses particules respiratoires, petites et grandes. Les chanteurs respirent aussi profondément, ce qui augmente les chances qu'ils inhalent des particules infectieuses.

Une dynamique de transmission similaire pourrait être à l'œuvre dans d'autres contextes où la respiration lourde et les conversations bruyantes sont courantes sur de longues périodes, comme les gymnases, les spectacles musicaux ou théâtraux, les conférences, les mariages et les fêtes d'anniversaire. Sur les 61 groupes de cas recensés au Japon entre le 15 janvier et le 4 avril, beaucoup impliquaient une respiration lourde à proximité, comme lors de soirées karaoké, d'encouragements dans des clubs, de discussions dans des bars et d'exercices dans des salles de sport, selon une étude récente publiée dans la revue Emerging Infectious Diseases.

Le taux d'attaque, c'est-à-dire le pourcentage de personnes infectées dans un lieu ou à un moment précis, peut être très élevé dans les lieux très fréquentés, les maisons et autres lieux où de nombreuses personnes sont en contact étroit et prolongé.

On estime que 10% des personnes atteintes de Covid-19 sont responsables d'environ 80% des transmissions, selon une étude publiée récemment dans Wellcome Open Research. Certaines personnes atteintes du virus peuvent avoir une charge virale plus élevée, ou produire davantage de gouttelettes lorsqu'elles respirent ou parlent, ou se trouver dans un espace confiné avec de nombreuses personnes et une mauvaise ventilation lorsqu'elles sont à leur point le plus infectieux de leur maladie, a déclaré Jamie Lloyd-Smith, un professeur de l'université de Californie, Los Angeles, qui étudie l'écologie des maladies infectieuses.