Coronavirus infection isn't just about hygiene and distance. It's about time, too.

[Yo_Mama_Been_Loggin]

By now, you've likely heard the main pieces of advice to avoid the coronavirus.

Wear a mask. Wash your hands with soap. Stay at least 6 feet from others. If you do gather with others, go outside rather than inside.

Still, there's one more aspect to infection that has received less attention. Growing evidence suggests that Covid-19 infection, like with other illnesses, is related to prolonged time exposed to the virus. The longer you stay in an environment that may contain the virus, the higher the risk of getting sick.

Dr. Erin Bromage, a comparative immunologist and professor of biology at the University of Massachusetts Dartmouth, summed it up with a short and sweet equation: "Successful Infection = Exposure to Virus x Time."

Bromage's simplified formula was part of a recent blog post explaining ways to lower your risk of catching Covid-19 that has been read over 15 million times in the past two weeks, he told CNN.

https://www.msn.com/en-us/health/medical/coronavirus-infection-isnt-just-about-hygiene-and-distance-its-about-time-too/ar-BB14gipI?li=BBnb7Kz

[Worried2020]

1. Makes sense to me - but I'd add in Age . . .

.
.

A bunch of teens hanging around together for a period of time is less dangerous because most of their immune systems are strong. Old farts like me, immune system is tired.

I figure at 69, along with failing health, if I'm exposed, and catch it -

I'm dead.



W

[Igel]

6. Separate out risk of infection from risk of severe case/death.

They're distinct.

What the OP's saying is you need a certain amount of virus to become infected. One droplet won't do. The longer you're around somebody that's got an active infection, the more likely the person'll chuck enough virus your way.

It's not just time. It's also how they're infectious. For example, one analysis of school closures came back with the odd conclusion that school closures did very little to slow transmission. Sure, the kids got infected, but they didn't pass it to their elders very much. Or, really, to each other, for the most part. Because when a kid gets COVID, by and large they don't cough and sneeze all over everything. They're shedding virus, to be sure--if they blow their nose. If they then shake hands and that person picks his nose, it's transmitted. But if the nose-blower washes her hands and nobody reuses the tissue with her snot, it's not going to jump to infect somebody.

So risk of infection is time x how infectious the person is.

But it's also dependent on you. I'm 61. My immune system's slowing down. So it may be that the amount of virus that a 20-something would shrug off without a problem takes root so that I'm actively infected.

If I do get infected, my risk of death is something like 1 in 300 or 400, according to the most recent immunological survey I've seen. If I were near 70, it would be a lot higher.

[OhZone]

2. I'm really confused by this -

I always thought if you got a virus, even if it was just a couple of microscopic individual virus particles, it would get into your cells and it multiply, and it would be off to the races.

I understand if you get a larger dose, it would overwhelm your defences faster, and make you sick faster, but what happens when you only get a handful of little corona's?

Why don't they eventually make you very sick?

[Wounded Bear]

3. It's about viral load...

Most people, a few virus particles will be handled by your immune system. But get a concentrated load and the immune system gets overloaded. Immuno-compromised people have a much lower threshold to it.

So yeah, it's common sense NOT to sit in an enclosed space, even a large one like a church, with a group of people that might include infected folks.

Same with masks. If you wear a cheapo mask with a 50% filtering rate, it helps a little. If the guy in the room with you has the same thing, his breath is filtered twice at 50%, which means it is filtered to 75% when you inhale it. If you both wear N95's (95% effective) your inhalation rate of filtered particle is reduced to about .5% or so.

[OhZone]

4. So it's actually possible to get a couple of -

flu, cold, or maybe even ebola virus particles and not get particulary sick?

Hmmmm!

How does your immune system deal with a new virus it never saw before if it's a tiny dose?

What does it do?

Would you get antibodies or is there something else that's attacking unknown invaders in small doses>

[Wounded Bear]

5. Any foreign entity can trigger an immune response...

"new" viruses will naturally be more effective because the generic response may not work.

Ingesting a "few" virus molecules would probably not trigger the body to generate antibodies if they immediately get flushed out by normal white cells and the bodily filters.

[WhiskeyGrinder]

9. "How does your immune system deal with a new virus it never saw before if it's a tiny dose?"

This is what a vaccine is. Your immune system attacks it and gains immunity.

[maxrandb]

12. From what I understand, we have cells that fight viruses that they've seen before, but

we also have Naive Immunity cells that are responsible for going after stuff that is new.

[DrToast]

8. Here's a good response I found on Reddit

In theory a single virus should be enough, yes. But in reality, a virus is unable to move on its own, it has to be moved. And unless it reaches an ACE2 receptor and gets accepted into the cell, no replication is going to happen. These things are small, they can easily get stuck somewhere where they can't do any harm. The more virus laden droplets you inhale, the higher the probability that some of those reach a place where their payload can do harm.

And then there is the question, whether the initial viral load makes a difference since a low initial load might give the immune system more time to get its act together. Not sure if there is a consensus on that yet.

There are viral infections where very small amounts are enough to infect you, noro (stomach flu) being one of them, there it's between 10 and 100 virus particles for an infection to happen.

[OhZone]

10. This is very helpful to my thinking, thanks.

My brother says I don't think logically enough and I want to be able to show him up! ha

Seriously, though, that kinda makes sense. A single or handful of certain kinds of viruses might get caught on a hair or nasal mucus and not be able to bind onto the cell it evolved to connect to. Or if it's in the blood, but it only binds to certain kinds of cells, it might not make it to that kind of cell before it degrades or somehow gets caught up. But if you get a huge viral load, it's more likely that some will get to where they can be a problem.

Very interesting.

I guess stomach virus is all set to bind to stomach cells and gets transported right there by eating something "infected."

So thanks, and thanks to Wounded Bear and Whiskey Grinder.

[ProfessorGAC]

11. That's Useful

The infection spreads due to chemical reactions that steal the raw materials to replicate.
Mass transfer limitations affect any reaction where one of the reactants is in limited supply.
In your reference, that's basically what's happening.
One reactant in physically limited from finding the other reactable components, like enzymes, proteins or amino acids in living cells.
We've been hearing about viral load for weeks.
This nicely explains why.

[ecstatic]

7. I figured that. Burlington had a huge sale this past weekend

The store was packed to the brim, with no social distancing and extremely long lines that took hours to get through. I didn't go, but I truly hope the people who did don't get sick.