It was discussed in another thread that I'll try to dig up, but the percentage of the population required to reach herd immunity goes up the more contagious a virus is. If way more people are infected then we think, then it points to some of the higher R0 estimates being accurate and would therefore require a much higher portion of the population to be immune before we reach herd immunity.
Yeah, I'm not an epidemiologist but I think the principle is simple: it's just a matter of getting the actual transmission rate below 1, so that any outbreak will naturally die out. If in the absence of any immunity the average infected person infects 3 others, but now 2/3 of people are immune, then the average infected person will actually only infect one other. Ditto for a transmission rate of four and 3/4 immunity, and so on.
It's worth noting, though, that the natural tendency during an epidemic is for the total number of infections to exceed the herd immunity threshold; I think the phrase to google is 'herd immunity overshoot'.
(It's also worth noting the serious problems with this study, as pointed out by other commenters.)
I saw that too when mucking with simple models. The percent infected overshoots (R0 - 1)/R0. So that is a threshold for herd immunity not the ultimate infection ratio. They're only equivalent under steady state conditions.
Also saw an study released by the CDC that estimated that the initial r0 in Wuhan was 5.8. Explains what happened in Northern Italy and New York. The epidemic achieved break out while most infected were still mildly ill or asymptomatic.
Another anecdote: someone online who works in a virus lab doing other stuff said that if you are ill, have a shower twice a day and rinse mouth with mouthwash to reduce viral load.
If you need to go out, when you come back, remove all clothes and wash and then have a shower.
I've heard that as well. Basically, the spread of the virus inside your body is exponential too, whereas the immune system's response time will be fairly static. So if you're exposed to a little, the immune system has time to respond before the infection gets out of control; if you're exposed to a large amount, by the time the immune system starts to respond, the virus is already widespread in your system.
Interesting - almost identical to the idea of not overwhelming relatively inflexible health services with spikes of new cases, only within a single human body?
Why wouldn't it be the other way around? If the virus replicates very fast, people with minimum infectious doses have a couple replication generations of extra time.
If the virus replicates more slowly, a large infectious dose would have the same impact as multiple replication generations.
I'm not asserting the above is what happens, I'm asking the question.
If it were 'less' exponential, and each cell only infected, say, 5 others, then you get to 500x late in the 4th generation.
In a cartoon example where a low exposure leads to 1 infected cell and a high exposure leads to 500 infected cells, the low exposure matters more if the reproductive factor is lower.
There is an interesting accidental study about this regarding norovirus. (Back in 2014 I think, not the 2017 Tennessee thanksgiving event)
Some guy vomited in a restaurant. Then you can clearly model the time from exposure to symptoms in everyone else based on how far away they were when the guy vomited. Though in this case the viral exposure was very high for everyone in the restaurant.
That's a theory I've heard before. I don't remember where, unfortunately. Does anyone have a source?
The basic theory is that if you catch the virus, you want to have it in your nose first so your body has time to start a response before it reaches your lungs.
If you get a large dose into your lungs at the start (perhaps because you work at a hospital with insufficient PPE) it's less likely to be mild.
> The basic theory is that if you catch the virus, you want to have it in your nose first so your body has time to start a response before it reaches your lungs.
That's a thought that has crossed my mind before: if it's better the farther up in the respiratory system the initial infection happens, then all that hand washing might be a bad idea, at least for the personal outcome. It depends a lot on wether you expect the full wave to eventually roll through until herd immunity or if you expect it to be stopped early, either by continued distancing until it's starved our by a vaccine.
>That's a thought that has crossed my mind before: if it's better the farther up in the respiratory system the initial infection happens, then all that hand washing might be a bad idea, at least for the personal outcome.
Huh? How does that figure? Hand washing will means less (or no) virii in your nose/mouth.
So, isn't it (a) good in itself, and (b) totally orthogonal to the infection happening "farther up in the respiratory system" (aside the positive, that if it happens and is further up, it will also be less viral content)
> Huh? How does that figure? Hand washing will means less (or no) virii in your nose/mouth.
If you make "first contact" by inhaling tiny droplets it's possible that they will make landfall right down in the lungs, whereas an infection from dirty fingers is guaranteed to start in the nose/mouth area and will already be an immune system project while it works it's way deeper down. Still worse than not getting infected at all, but if you assume that it will eventually hit you anyways, easing into the infection via the nose would surely be preferable to starting in the lungs where it's actually dangerous.
The reverse of this would be accumulating an infective dose from the leakage amount allowed through by PPE while working in extreme exposure. I doubt that there is empirical data regarding viruses, but everything we've learned about particulate emissions suggests that smaller particles reach deeper into the lungs. So it seems quite convincing to me that people who do fall ill despite PPE fall ill harder. Might explain the prominent medical worker deaths.
I couldn’t get tested so not 100% that I actually had covid but as soon as I started having some symptoms I started gargling with diluted hydrogen peroxide and rinsing my sinuses with a strong saline solution. I can’t see how this would hurt and why this isn’t recommended given that the virus replicates in the nose and throat.
The viruses are replicating inside your cells. You can't just "disinfect" living tissue without killing it. There is a reason why medicine relies on evidence and does not recommend whatever random "treatment" someone came up with.
And you disinfect your mouth because disinfecting doesn't mean killing your mouth/tongue tissue. There are several mouthwashes on the market with antibacterial/antiviral properties, dentists do the same, etc...
In Bavaria they are only testing people with symptoms and the positive rate is around 10% [1].
Everybody thinks they have it but the symptoms could also be down to a cold. I am not pointing this statistic out to prove you wrong -- I just find it interesting.
Probably the only time it's appropriate for outrage culture and to focus on the negative is exactly right now.
Shame and tell everyone whenever possible to stay the fuck inside because those are going to be the people that make you stay in lockdown for 6 months instead of 2.
It appears Seattle may have "flattened the curve" too much as new cases have flatlined.
Sounds good!? But healthy young people aren't building up antibodies.
Which means when we end social distancing, the virus will start spreading just like it did before.
The goal here isn't to prevent everyone from getting it. The goal is to slowly build up heard immunity, in a way that doesn't overly burden the healthcare system, and to hopefully learn some new treatments along the way.
Building up herd immunity without overwhelming the hospital system would take years. Instead we need to prevent spread as much as possible while testing is ramped up. Once we have free, fast, widespread testing, we can remove restrictions without risking new outbreaks, because new cases will be caught quickly.
I am not so sure herd immunity is a goal. The idea is indeed to avoid overrunning the healthcare system, with an expectation that we can get the majority of the population successfully through the system. It's not well-known that we'll build even short term immunity, let alone long to medium term immunity.
If new cases flatline, that's good! If we can avoid everyone getting it, that's even better! If the globe can get a handle on things, we don't need to solely consider worst-case scenarios.
No, it won't. If people mingle and fail to "flatten the curve", the whole mess will be over sooner, albeit with more dead old people. If you believe you can starve the virus of hosts, you're delusional.
...preliminary figures released on Wednesday by the Centers for Disease Control and Prevention show that adults ages 20 to 44 represent nearly one-third of U.S. coronavirus patients whose ages are known.
CDC published numbers on Wednesday night that 40% of hospitalizations for COVID-19 in the US are adults younger than the age of 54.
Sure they're not fatalities, but do you really want to go to an overcrowded hospital for COVID-19? (Will be worse when ventilators run out and hospitalization can't help you nearly as much)
Only 2.8% of all hospitalizations that required an ICU were people under 45 years old, though, and we have no idea what underlying health problems they may have had.
The second link summarizes how unhealthy are millenials. What will happen when ICU capacity is not enough? There was another study suggesting that being exposed to the virus fast vs slow makes the difference, can't find it now. Crowded hospitals with millenials will surely make a difference for all.
What do you mean by "so many"? Singapore appears to be an amazing success story in containing C19.
They are using aggressive contact tracing as part of that, so if it were spreading like wildfire through A/C vents surely that wouldn't be effective and they would have a much faster growth rate of cases.
I don't think the assertion is that it's spreading through vents, just that spending time in a very air conditioned room mimics some of attributes of winter that make the spread of respiratory viruses more likely (dry air, dry nasal passages)
There may be something to this. If you look at the actual cases in Singapore, they seem to be clustered around two specific locations, one company and a single event which I would presume was held inside a single big hall.
I'm in Singapore, and life here goes on pretty much as it always has. Except for a larger than normal number of people wearing masks, you can't really tell that this is ongoing.
That said, the government is doing a lot to keep it that way. There is intensive contact tracing, and companies register people going in and out of their offices (to help tracing), if you're sick you're supposed to stay at home, and so on.
