How many individual virus are needed to start an infection?

[antares4141]

I used to think I was more resistant to colds and flu cause I handn't had one as far as I can remember the first 10 years into my illness. But around 13 years in I had a pretty persistant cold and than again a couple of years later another persistant one.

Oh, and just back in February I had a mild cold with a mild dry cough, profound sneezing fits, and noticeable change in taste. I would be interested in getting an antibody test to see if I have already been exposed to covid19.

 

[roller]

it has been stated by researchers a many times that droplets are the least problem. commonly used surfaces are more dangerous. and of course also your pets, that may catch it outside.
its in the rainwater/clouds (via droplets), on the floor in the whole environment.
its never been different, from what i understand. with pretty much all pathogens.

the severity of the disease is dose dependent.
in germany, they found that ppl on ventilators had best chances to die and found as the reason the close handling required by medical staff (im guessing - and the contaminated equipment too?).
in UK more than 51 percent on ventilators dont make it. they die.

so, would it be best, we catch small doses and get used to it (producing antibodies slowlyslowly...) ?

nobody knows why germany has such a low death rate.
im wondering, if it is because ppl are not hospitalized.
they are sent home. to self-quarantine.

 

[roller]

i understand, the "top virologist" drosten made a remark like, that we endure more...
as in "krupp stahl"... i wondered....

some research is guessing low death-rates may have to do with previous vaccinations in countries.

im wondernig, if in germany the previous super-deadly-flu attack (must have been 2017/2018 - killed 25,000 germans in the flu-season) left some useful antibodies, helping with corona virus ?

 

[roller]

also puzzling....

this mega-flu 2017-2018 in germany... very very deadly...
wasnt there and didnt really notice this obviously "huge thing"... despite reading newspapers...

why did this one NOT spread across europe likewise, or to china - when employees visited german plants?

 

[Booble]

It is ALL droplet related. The virus spreads via droplets. Period. The difference is if the droplet is picked up in the air or from a surface. In the air, it doesn't travel too far but if you are emoting a lot (like in church singing and waving your hands) and in an enclosed spaces, the tiniest droplets can stay floating around for a significant amount of time. Up to, I believe, 3 hours. Lots of people in enclosed space means lots of droplets. Generally speaking, the virologists all say that you are most likely to catch from prolonged close contact to someone or a group in an enclosed space. While you can catch it from air that you walk through after the infectious pereson is gone....or surfaces that someone coughed on, the majority will catch from close, prolonged interaction with someone who is symptomatic. That's why places that do strong contract tracing are doing better. Again, you can catch from asymptomatics and you can catch it from surfaces and we should be super mindful and careful of ALL of that. It's still more likely to get you sick when you get the large dose from being within 6 feet of someone for a 10+ minutes who is sick and symptomatic.
Note: I'm not trying to minimize at all. I'm scared shitless of it too and staying in 99.9% of the time.

 

[antares4141]

It is ALL droplet related. The virus spreads via droplets. Period. The difference is if the droplet is picked up in the air or from a surface. In the air, it doesn't travel too far

My thoughts were that particularly inhaling the droplets directly from somebody who just exhaled them would put you at high risk. Yes all those droplets settle on surfaces and you could pick it up that way but I would think the exposure would be far less.

Conversely if you were to handle a shopping cart without gloves or not disinfect areas you are going to touch. (preferably both!) I think that would be a potentially high risk again. Or handling a gas pump without gloves.

Because people touch their nose and face then touch the object they are depositing a relatively higher concentration of "fomites" on objects. Fomites are objects or materials which are likely to carry infection, such as clothes, utensils, and furniture.)

Or maybe you go into the store and meticulously wear gloves, wear respirator, use purel every 5 seconds, don't touch your face. Then come home, take your shoes off with your bare hands than pick your nose. That might put you at higher risk then breathing air inside a grocery store with just a paper mask.

In a way I tend to agree with what Hip was intimating to that touching surfaces then your face is where the highest risk is. But only because it's so easy to have just one lapse of judgment to contract the disease.

 

[Booble]

Yes, I think you are right that the exhale gives you the most exposure. Especially with a cough or over a certain amount of time (a certain number of concentrated breaths).

And also yes -- touching your eyes and nose after touching an item that has been recently coughed on by an infected person would also give you a large dose.

The good news is that it degrades over time on items so there is less and less virus on the surface as time passes. It has a certain half-life depending on the surface. And the virologists also say that someone would have to really cough right on the surface (for example pick up a can of beans and cough right on it, put it back on the shelf, and then you pick it up.) That's why we are seeing minimal transmission from food items and maximum cases from close contacts.

 

[roller]

this bears the question:
how many of the emitted human droplets do hold an infective virus?

so... if an average infected person does an average sneeze, how many virus particles are ejected ?

 

[Booble]

Well, if everyone wears a mask when they are out in public places, then nobody's droplets will get very far. As our mayor likes to say, "My mask protects you and your mask protects me." We are all in this together.

 

[antares4141]

Yes, I think you are right that the exhale gives you the most exposure. Especially with a cough or over a certain amount of time (a certain number of concentrated breaths).

And also yes -- touching your eyes and nose after touching an item that has been recently coughed on by an infected person would also give you a large dose.

The good news is that it degrades over time on items so there is less and less virus on the surface as time passes. It has a certain half-life depending on the surface. And the virologists also say that someone would have to really cough right on the surface (for example pick up a can of beans and cough right on it, put it back on the shelf, and then you pick it up.) That's why we are seeing minimal transmission from food items and maximum cases from close contacts.

I was thinking more along the lines you touching something somebody else touched. Like door knobs, toilet seats, car gas pumps, shopping cart handles etc. Then your face.

This artcle has some good info:
Here's how long the coronavirus will last on surfaces, and how towww.livescience.com › how-long-coronavirus-last-surfaces

Or you're touching something somebody else touched or coughed on, then touching your mask.

Not sure if anyone could come up for a reason not to do this but I suspect heat guns or hair dryers on your masks after every use.

You can rotate them also. So they set for a few days before they get used again. But it's anybodies guess on how long and at what temperatures it takes for viruses to be inactivated this way.

Suspect a hair dryer would inactivate viruses pretty quickly though.

And while using masks you have to not touch your mask without first washing your hands which I suspect is really hard.

And I often wondered how many people actually keep their mask on when they are having a sneezing or coughing fit? Realistically if you did this it would become unusable from all the mucus you expel onto it. So bringing a handkerchief or some such item to "muffle" your cough. As opposed to the fake mouth cover where you put your closed fist in front of your mouth which doesn't help at all and contaminates your hand.

Also wondered if as the water droplets dry out in your mask if that frees the virus to pass right through it. So if you go to multiple places and take your mask off between places does your mask allow all the trapped now dry particles from the last place you were at to pass right through into your lungs?

Best solution is to shop online and have items brought out to your car.

 

[ljimbo423]

Or you're touching something somebody else touched or coughed on, then touching your mask.

Not sure if anyone could come up for a reason not to do this but I suspect heat guns or hair dryers on your masks after every use.

You can rotate them also. So they set for a few days before they get used again. But it's anybodies guess on how long and at what temperatures it takes for viruses to be inactivated this way.

I read a couple of articles that said the covid 19 virus becomes inactivated after about 3 hours on absorbent surfaces like cardboard, cloth etc. and up to 3 days on hard non-porous surfaces like plastic, steel, etc.

 

[antares4141]

In the article I linked above it said nine days if it resembles other coronaviruses:

"They concluded that if this new coronavirus resembles other human coronaviruses, such as its "cousins" that cause SARS and MERS, it can stay on surfaces — such as metal, glass or plastic — for as long as nine days (In comparison, flu viruses can last on surfaces for only about 48 hours.)"

Being masks resemble cardboard you may be ok with a couple of days but I don't know weather I would want to take my chances with that.

 

[ljimbo423]

In the article I linked above it said nine days if it resembles other coronaviruses:

"They concluded that if this new coronavirus resembles other human coronaviruses, such as its "cousins" that cause SARS and MERS, it can stay on surfaces — such as metal, glass or plastic — for as long as nine days (In comparison, flu viruses can last on surfaces for only about 48 hours.)"

Being masks resemble cardboard you may be ok with a couple of days but I don't know weather I would want to take my chances with that.

This is dated March 17 2020. However, there's nothing wrong with being overly cautions with this virus. I'm pretty sure I heard Anthony Fauci qoute this study a few days ago on MSNBC.

The virus that causes coronavirus disease 2019 (COVID-19) is stable for several hours to days in aerosols and on surfaces, according to a new study from National Institutes of Health, CDC, UCLA and Princeton University scientists in The New England Journal of Medicine.

The scientists found that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was detectable in aerosols for up to three hours, up to four hours on copper, up to 24 hours on cardboard and up to two to three days on plastic and stainless steel.

The results provide key information about the stability of SARS-CoV-2, which causes COVID-19 disease, and suggests that people may acquire the virus through the air and after touching contaminated objects. The study information was widely shared during the past two weeks after the researchers placed the contents on a preprint server to quickly share their data with colleagues.

Source

 

[roller]

only few people seem to develop that most wanted antibodies after covid infection.

are there data/statistics on how many people develop antibodies after the regular flu ?

so, to see if its perhaps normal that flu-viruses leave people without any much useful antibodies ?

 

[antares4141]

only few people seem to develop that most wanted antibodies after covid infection.

are there data/statistics on how many people develop antibodies after the regular flu ?

so, to see if its perhaps normal that flu-viruses leave people without any much useful antibodies ?

I think they call the corona family of viruses "colds" rather than "flue"
And the information I came across suggest that immunity last's only a few years after you have contracted any particular strain of corona virus.

Flu immunity is a good question. I didn't look very hard but couldn't find any information on how long immunity last's after you have gotten any particular strain of flu. But they suggest that vaccines are only good for 6 months. And of course there are different strains from year to year so something that you might have aquired immunity for this year won't necessarily help you the next.

I haven't had a flu virus for 35 years interestingly. I think I have had it once for sure in my 20's and maybe one other time in my adolescence. Obviously I have been exposed to them in the intervening 35 years. I suspect this may be typical experience for others. So I am guessing there must be some other circumstances that apply to how vulnerable people are to any of these types of conditions.

Like for instance what they call innate immunity:
Innate immunity refers to nonspecific defense mechanisms that come into play immediately or within hours of an antigen's appearance in the body. These mechanisms include physical barriers such as skin, chemicals in the blood, and immune system cells that attack foreign cells in the body