To get current infected you then have to multiply it by communication^(days to death), something like 1.1^14, with the first term varying depending on population density and lockdown measures, and the second on how on the ball that locality is for detecting cases and keeping people alive.
Yes. Stanford's recent study says 2-4% of the population of Santa Clara County has been infected. Those are probably reasonable bounds. Herd immunity is around 80% for this. So about 20 to 40 times as many people need to die before it's over.
That test needs to be repeated weekly to get the growth rate. (Preferably not with the scheme from Verity, which requires that you sign up for a Google account.[1]) Now that California hospital admissions and deaths for COVID-19 have flattened, growth should be linear for a while. But the rate of increase is still not really known.
Still, we're probably looking at a year and a million deaths in the US, within a factor of 2 either way.
[1] https://verily.com/stories/the-project-baseline-covid-19-pro...
There is a very major risk with extrapolating the Santa Clara data in the motivation of those being tested has not been controlled. Who is more likely to want to know they have been infected - those who have had classic COVID-19 symptoms or those who haven’t.
Source? Right now, that seems unknown - too soon to tell. A few months of measuring antibody levels and we'll know more.
https://www.thelancet.com/journals/laninf/article/PIIS1473-3...
I would be surprised if, after this current wave of infections, the percentage of people with antibodies in the US is higher than the low single digits.
Herd immunity without a vaccine is a pipe dream. Our best bet is to massively ramp up testing and contact tracing and really start pushing the number of infections down to a point where parts of society can start functioning again.
In the Netherlands a fatality rate of 0.5% would mean it'd take about a year for herd immunity to kick in assuming we managed sustain the peak that occurred about 2 weeks ago (and it's somewhat dubious whether the healthcare system actually can sustain that peak).
That's because just like in a war, it isn't realistic to expect the frontline soldiers to stay in combat for longer than weeks at a time before they start to exhibit PTSD and their effectiveness begins to drop.
Unless we have large reserves of doctors and nurses to rotate in and out I think we should be very careful not to take them for granted.
328.2 million (Approximate population of the US [1]) * 80% for herd immunity (based on an R0 5.7 [2]) * 1% = 2.6 million people die.
If the fatality rate is 0.5% instead, then 1.3 million people die If the fatality rate is 0.1%, we're still looking at ~260k-ish people.
That's pretty grim.
This situation is still developing so hopefully those numbers get adjusted downwards as later information becomes available.
For reference, ~1.2 million people died to heart attacks and cancer in 2017. [3]
[1] https://www.census.gov/popclock/ [2] https://wwwnc.cdc.gov/eid/article/26/7/20-0282_article [3] https://www.cdc.gov/nchs/fastats/leading-causes-of-death.htm
Total Covid deaths are already at a "mild flu season" level already after a month and continuing some level of exponential growth after social distancing.
It's sad and awful but it seems like with the current administration approach, the response of ramped up contract tracing has pretty much flown away and with these figures, we're looking 500K deaths, 250K over the next two month and another 250K over a longer period. Hide your parents...
NYC, for example, has 123k confirmed cases. Multiply by 50, and you have 6.1M, which is close to 70% of the total population.
You should read it before commenting.
The problem is, a vaccine is also a pipe dream. So we're going to have to all get infected over some sort of timeline that doesn't cause societal collapse. Also known as flattening the curve.
Really want to get a test on myself and family. We had something that near hospitalized me, but the kids barely registered being sick.
Yes and no.
A disease is endemic when R0 x S = 1 [0]. R0 for SARS-CoV-2 is estimated to be 2.5 to 3.5 and some models predicting a much higher 5.7 [1].
The herd immunity threshold is given by (1 - S)%, which implies when R0 = 2.5, 60% of the population would need to be immune; similarly 71.42% and 82.45% for R0s, 3.5 and 5.7, respectively.
I believe the SIR model [0] answers those questions. 3blue1brown's video on the topic is super digestible and informative [1].
In short, the discovery of a prophylactic if not a therapeutic treatment are our best immediate bets, absent which, quarantines and lockdowns will have to persist to curb the spread of a disease as infectious as covid-19 whilst we patiently wait for an effective vaccine against it [2].
[0] https://en.wikipedia.org/wiki/Compartmental_models_in_epidem...
[Edit: 'No symptoms experienced at time of positive test results' is intended to mean the same as 'no symptoms experienced yet at time of positive test results'.]
Highly unlikely these are all just people who have produced antibodies as part of a yet-to-be overrun immune response.
Like, it was for a while impossible to get a test if you are not experiencing multiple symptoms AND can make a case that you might have been exposed via interacting with someone who has traveled. Even now I don't think they're giving the test if you don't have a fever. It's implausible that 50% of the people tested by the official pathway had no symptoms because the official pathway is not available when you have no symptoms.
But if you mean that you've seen a 50% "asymptomatic transmission" rate, in other words studies like this that purport to test a bunch of people at random and see how many of them have COVID-19, note that this definition of "asymptomatic" may include many with symptoms not severe enough to be hospitalized -- in other words they might have been feverish and coughing but not moreso than a typical cold. I myself have had a really nasty cough but it is not "dry" but "productive" and it has not come with a fever -- I would really love to be tested but right now that does not seem to be possible! Maybe I am in this above grouping of "asymptomatic" folks.
The OP article suggests that as many as 98-99% of cases might not involve hospitalization and therefore might be cases like mine (assuming I do indeed have COVID-19, maybe I don't). Now it is likely that there is some sort of selection bias in how they recruited candidates, but still it tends to push that number above your high end of 70%, suggesting maybe it's closer to 80 or 90%. On the other hand while the paper says that it did its due diligence subtracting out the test's false-positive rate, a rather small error here can have a big impact on that number because there are so few true positives right now.
In some ways the paper's claim is a bit of good news, it means that this disease has much lower mortality than we were originally told. (There may be lower bounds on mortality -- I have heard of one town in Italy where 1% of its population is gone due to COVID-19 in which case that would seem to be a good lower bound.) In other ways it is bad news, it means that this disease, still with nontrivial mortality, is going to be much less affected by quarantine countermeasures and the social distancing stuff is really the only reason it is spreading as slowly as it is, so that we need to endure the pain of isolation for much longer -- potentially until testing becomes widespread and cheap.
That may not be too much longer, as mentioned in a previous HN comment/story [1] that if you can get testing to work with the old Sanger sequencers used in the Human Genome Project you can maybe ramp up to 200,000 samples/day at first with possibilities to go up to 1M/day once you solve additional logistical problems. Before that the production of kits and sourcing of reagents may be your limit.
An example where testing was conducted without requiring symptoms first: https://taskandpurpose.com/news/uss-theodore-roosevelt-sailo...
If it's the nasal swab-PCR test that most civilians are getting, then the claim of "asymptomatic" must be accompanied by a "yet". We can't really conclude anything for at least two weeks after the positive result -- after seeing whether those people ever develop symptoms.
If it's blood-antibody testing, then we can give the statement a little more weight, because a positive result would mean the infection is in a later stage or even past. I have no idea whether the Navy is using these tests.
This is in the bay area, where people were very quick to self-quarantine. Most people have been working from home since early March. They were asking people to break their self-quarantine to get tested without having any symptoms?
This is only a small comfort since it means we may have had about 8.75 million infected and presumably now immune in the USA. Or about 2.6%. There’s still a long way to go in that case.