In response to some questions of kathleen's and Third of Five:
[Disclaimer: I am not an expert. It's best to read original material from reputable sources, regularly, as more is being learned by scientists and medics every day and information changes, often rapidly].
1. Third of Five: According to your nursing instructor ("mentor"), "viral load" is the main consideration in disease transmission and therefore asymptomatic transmission is "not possible". This is not what experts are saying, according to much material that I am reading. Yes, viral load is a big factor in transmission, but not the only factor. It sounds like your mentor is saying that asymptomatic people either have no viral load or only a small viral load. This is not accurate.
If there are older, weaker or scarce particles of the virus in the air or on an object or person near you or that you touch, experts say you would likely not get infected, even if you had close contact, due to low viral load (but this is not an absolute guarantee of safety).
If someone who is known to have CV sneezes close to you, they are expelling droplets which likely contain heavy viral load (very contagious). If the infected droplets fell on you or onto something you touch and you then touch your face you have potentially just infected yourself with the virus. As we all know by now (I hope) the portals of entry for the virus are our mouth, nose and eyes. We are being constantly reminded now to STOP touching our face! It's a major way we can protect ourselves (although it's an often unconscious human impulse and hard to break the habit - we have to become more conscious of what we're doing with our hands).
But too, if someone is asymptomatic yet has CV, and they sneeze nearby, you could also be infected by them. Their viral load, therefore, may be significant yet they are either not yet ill or may not become ill - these different outcomes for various people are not yet fully understood, as far as I know.
Therefore, it would be interesting for you to check with your mentor and verify that you understood her correctly and/or if she has received new information that has updated the information she had been working with. It is dangerous for a health care worker, especially a teacher, to be teaching the incorrect information that asymptomatic people can't infect others. I believe experts are saying that is not the *main* driving force behind the worldwide contagion but it is significant enough that it's a serious factor to consider. An asymptomatic person could have a viral load strong enough to endanger others.
2. kathleen - re the virus being in the air: I agree that it has been quite confusing as the information seems to change daily. For at least one day I got the scary impression from various reports that indeed the virus was airborne (which would mean swirling all around us, making me think we're just doomed to get it).
I believe, from various sources I've read, that experts are now saying that CV is *not* an *airborne* disease. However, the infection can spread from person to person via droplets in the air that are released by infected persons, by coughing or sneezing, or by touching objects with their hands that may be contaminated with the virus if they have previously touched their face (nose, mouth) and CV is then transferred to their hands and thereafter potentially to objects or persons that they touch.
The distinction between being airborne and being passed by droplet or transfer can be confusing. The droplets are in the air. But they're only present if an infected person has expelled them there.
3. Here is an article that discusses the means of transfer and the "shelf life" of the virus (to answer kathleen's question about how long the virus can last on a surface).
First, I have laid out excerpts that address some of the specific common questions. After that I have added more statements from the article.
It's worthwhile to read the entire article (I left out parts about experiments they conducted to find out the information they present). It's also a good idea to keep updated with the latest information that comes from the findings of the ongoing experiments and the current conclusions being stated by the experts. And, of course, as always, it's good practice to check the source of your information.
I think the doctor's comment that the virus in the air as you pass by is like "foggy breath on a frosty day" is a good image, and reassuring.
However, too, now they are saying that in addition to the virus being expelled into the air by an infected person's sneeze or cough, it can also be released by the mere acts of speaking and breathing. Hence the value of the 6-foot distance between us that we should vigilantly try to maintain (many people don't seem to know what 6-feet looks like and they wander too close). It's likely this is how choir members got infected, being in close quarters and singing - all that breath being forcefully expressed into the air next to each other. So unfortunate.
The article, for more complete information:
Economic Times (NY, April 2, 2020)
By Apoorva Mandavilli
Excerpts:
“The coronavirus can live for three days on some surfaces, like plastic and steel, new research suggests.”
“When the virus becomes suspended in droplets smaller than 5 micrometers — known as aerosols — it can stay suspended for about a half-hour, researchers said, before drifting down and settling on surfaces where it can linger for hours.”
“The virus lives longest on plastic and steel, surviving for up to 72 hours. But the amount of viable virus decreases sharply over this time. It does poorly on copper, surviving four hours. On cardboard, it survives up to 24 hours, which suggests packages that arrive in the mail should have only low levels of the virus — unless the delivery person has coughed or sneezed on it or has handled it with contaminated hands.”
“That’s true in general. Unless the people who handle any of these materials are sick, the actual risk of getting infected from any of these materials is low, experts said.”
“Everything at the grocery store and restaurant takeout containers and bags could in theory have infectious virus on them,” said Dr. Linsey Marr…”
“Marr said based on physics, an aerosol released at a height of about 6 feet would fall to the ground after 34 minutes. The findings should not cause the general public to panic, however, because the virus disperses quickly in the air.”
“It sounds scary,” she said, “but unless you’re close to someone, the amount you’ve been exposed to is very low.”
“Marr compared this to cigarette smoke or a foggy breath on a frosty day. The closer and sooner another person is to the exhaled smoke or breath, the more of a whiff they might catch; for anyone farther than a few feet away, there is too little of the virus in the air to be any danger.”
Summary of article (a bit repetitious with info from above):
“The coronavirus can live for three days on some surfaces, like plastic and steel, new research suggests. Experts say the risk of consumers getting infected from touching those materials is still low, although they offered additional warnings about how long the virus survives in air, which may have important implications for medical workers.
“The new study, published on Tuesday in the New England Journal of Medicine, also suggests that the virus disintegrates over the course of a day on cardboard, lessening the worry among consumers that deliveries will spread the virus during this period of staying and working from home.
“When the virus becomes suspended in droplets smaller than 5 micrometers — known as aerosols — it can stay suspended for about a half-hour, researchers said, before drifting down and settling on surfaces where it can linger for hours. The finding on aerosol in particular is inconsistent with the World Health Organization’s position that the virus is not transported by air.
“The virus lives longest on plastic and steel, surviving for up to 72 hours. But the amount of viable virus decreases sharply over this time. It does poorly on copper, surviving four hours. On cardboard, it survives up to 24 hours, which suggests packages that arrive in the mail should have only low levels of the virus — unless the delivery person has coughed or sneezed on it or has handled it with contaminated hands.
“That’s true in general. Unless the people who handle any of these materials are sick, the actual risk of getting infected from any of these materials is low, experts said.
“Everything at the grocery store and restaurant takeout containers and bags could in theory have infectious virus on them,” said Dr. Linsey Marr, who was not a member of the research team but is an expert in the transmission of viruses by aerosol at Virginia Tech in Blacksburg. “We could go crazy discussing these ‘what-ifs’ because everyone is a potential source, so we have to focus on the biggest risks.”
“If people are concerned about the risk, they could wipe down packages with disinfectant wipes and wash their hands, she said.
“It is unclear why cardboard should be a less hospitable environment for the virus than plastic or steel, but it may be explained by the absorbency or fibrous quality of the packaging compared with the other surfaces.
“The virus lives longest on plastic and steel, surviving for up to 72 hours. But the amount of viable virus decreases sharply over this time. It does poorly on copper, surviving four hours. On cardboard, it survives up to 24 hours, which suggests packages that arrive in the mail should have only low levels of the virus — unless the delivery person has coughed or sneezed on it or has handled it with contaminated hands.
“That’s true in general. Unless the people who handle any of these materials are sick, the actual risk of getting infected from any of these materials is low, experts said.
“Everything at the grocery store and restaurant takeout containers and bags could in theory have infectious virus on them,” said Dr. Linsey Marr, who was not a member of the research team but
A study that is being reviewed by experts bears out this fear. And another study, published March 4 in JAMA, also indicates that the virus is transported by air. That study, based in Singapore, found the virus on a ventilator in the hospital room of an infected patient, where it could only have reached via the air.
“Marr said that the World Health Organization has so far referred to the virus as not airborne but that health care workers should wear gear, including respirator masks, assuming that it is.
“Based on aerosol science and recent findings on flu virus,” she said, “surgical masks are probably insufficient.”
“Marr said based on physics, an aerosol released at a height of about 6 feet would fall to the ground after 34 minutes. The findings should not cause the general public to panic, however, because the virus disperses quickly in the air.
“It sounds scary,” she said, “but unless you’re close to someone, the amount you’ve been exposed to is very low.”
“Marr compared this to cigarette smoke or a foggy breath on a frosty day. The closer and sooner another person is to the exhaled smoke or breath, the more of a whiff they might catch; for anyone farther than a few feet away, there is too little of the virus in the air to be any danger.
“Munster noted that, overall, the new coronavirus seems no more capable of surviving for long periods than its close cousins SARS and MERS, which caused previous epidemics. That suggests there are other reasons, such as transmission by people who don’t have symptoms, for its ability to cause a pandemic.”
https://economictimes.indiatimes.com/magazines/panache/how-long-can-coronavirus-live-on-surfaces-or-in-the-air/articleshow/74690737.cms