Latest in science: How much virus does it take to make you sick?

[SoonerPride]

When experts recommend wearing masks, staying at least six feet away from others, washing your hands frequently and avoiding crowded spaces, what they’re really saying is: Try to minimize the amount of virus you encounter.

A few viral particles cannot make you sick — the immune system would vanquish the intruders before they could. But how much virus is needed for an infection to take root? What is the minimum effective dose?

For SARS, also a coronavirus, the estimated infective dose is just a few hundred particles. For MERS, it is much higher, on the order of thousands.

The new coronavirus, SARS-CoV-2, is more similar to SARS and, therefore, the infectious dose may be hundreds of particles, Dr. Rasmussen said.

But the virus has a history of defying predictions.

Generally, people who harbor high levels of pathogens — whether from influenza, H.I.V. or SARS — tend to have more severe symptoms and are more likely to pass on the infection.

But with the new coronavirus, people who have no symptoms may have just as much virus in their bodies as those who are seriously ill, some studies suggest.

Longer article at the link

https://www.nytimes.com/2020/05/29/health/coronavirus-transmission-dose.html?referringSource=articleShare

[stopdiggin]

1. mask is still the answer

Answer: We still really don't know (precisely). But larger doses are definitely to be encountered indoors, in non-ventilated environments, and in larger droplet transmission (coughing, sneezing, speaking).

But they noted that aerosols, because they are smaller than 5 microns, would also contain much less, perhaps millions-fold less, virus than droplets of 500 microns.
“It really takes a lot of these single-digit size droplets to change the risk for you,” said Dr. Joshua Rabinowitz, a quantitative biologist at Princeton University.
Apart from avoiding crowded indoor spaces, the most effective thing people can do is wear masks, all of the experts said. Even if masks don’t fully shield you from droplets loaded with virus, they can cut down the amount you receive, and perhaps bring it below the infectious dose.
“This is not a virus for which hand washing seems like it will be enough,” Dr. Rabinowitz said. “We have to limit crowds, we have to wear masks.”

Best practice: Wear a mask when indoors, or around other people.

[SoonerPride]

2. Precisely.

The biggest takeaway is masks are essential.

[Blue_true]

3. I was sitting in auto traffic behind a smoker today.

Not moving, I smelled cigarette smoke. Looked around the guy in the car ahead was smoking. We were at least ten feet apart. Because I was in my vehicle, I didn't have on a mask.

[LizBeth]

5. That is what I figure. Whatever reduces intake lowers risk.

[LisaL]

4. This one is a very strange virus.

[JudyM]

6. I read research a few days ago hypothesizing that it was "nonzero," meaning 1 virion could do it.

Which explains how people can contract it from simply speaking with someone.

[SoonerPride]

7. 😳

😳

[Hugin]

8. K&R