3 ms·

Nobody knows the asymptomatic infection rate. Without that, differences in mortality numbers between countries are meaningless, because testing rates are all ov

Nobody knows the asymptomatic infection rate. Without that, differences in mortality numbers between countries are meaningless, because testing rates are all over the place. Explaining the differences by overrun hospitals is jumping the gun I think.

Ozzie_osman 7y ago
Exactly. Fatality rates are mostly just a function of a country's testing (how much testing they're doing, and how biased the sample is). If you're only testing a small # of people with severe symptoms, obviously the fatality rate will look really high. If you're testing a much wider section of the population, and testing people who aren't severely sick, the number will look lower. Some examples: - Iceland randomly tested people in the general population (no symptoms), they found ~1% of people tested positive, and half of those had no symptoms (and so probably wouldn't be tested). [1] - Italy tested an entire village (the village had a cluster of cases), 3% tested positive, of which half had no symptoms. - One professor used the Diamond Princess cruise ship as a baseline, and estimated anywhere from 0.025%-0.625% [2] - China had a fatality rate of 17% initially, which went down to 0.7% if you only consider symptom onset _after_ Feb 1st. [3] Of course, there are a lot of other factors, and it's possible that the rates end up in fact being really high, but there's an argument that we just don't know how many people are infected and fatality ends up being a lot lower then just dividing # of deaths by # of confirmed cases would have you believe. Just to be clear: even the lower case scenarios are really serious and worrying, and I'm definitely not in the "this is just another flu" camp. But there's a huge range of uncertainty here. [1] https://www.government.is/news/article/?newsid=f96a270c-66e8-11ea-945f-005056bc4d74 https://www.government.is/news/article/?newsid=f96a270c-66e8... [2] https://www.statnews.com/2020/03/17/a-fiasco-in-the-making-as-the-coronavirus-pandemic-takes-hold-we-are-making-decisions-without-reliable-data/ https://www.statnews.com/2020/03/17/a-fiasco-in-the-making-a... [3] https://www.cebm.net/covid-19/global-covid-19-case-fatality-rates/ https://www.cebm.net/covid-19/global-covid-19-case-fatality-...
cashsterling 7y ago
I can't stress enough how important this factor is... without widespread randomized testing of the population, we have no idea what the true infection rate is or how widespread the virus really is. Our current stats have a huge selection bias problem. This is why it is so important that we take social distancing, self hygiene, and shelter-in-place measures really seriously in order to protect those among us who may be more susceptible to severe infection. The silver lining: the more widespread the virus, and hence the number of asymptomatic cases... lower the actual the severity statistics are. i.e. we know "number of deaths", "number of hospitalizations", and "number of positive cases". Right now, when we calculate our various severity rates, we are putting "number of positive cases" in the denominator because we don't know the number of actual infections. There is an unknown multiplier (>= 1) relating positive cases to infections. All our severity statistics need to be divided by this unknown multiplier. But right now, since we don't know what it is... the responsible thing to do for reporting and policy decisions is assume it is 1 (worst case). It is not 1... it is greater than 1... we all know that. But how much is a tough question to answer properly without proper statistical sampling of the population. There are modelling studies and estimates that suggest value ranges for the multiplier, but I don't want to spread potentially false information on a public forum.
- WalterSear 7y ago
  It's not a silver lining: the number of serious cases remains the same and our ability to contain the epidemic is less effective.
  - edanm 7y ago
    It is, because assuming that having the virus gives some immunity, then if we find out that 90% of people are asymptomatic, that implies that the number of cases we have right now won't go up much more (since many people have already had and recovered from Coronavirus).
deleted 7y ago
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Ozzie_osman 7y ago

Exactly. Fatality rates are mostly just a function of a country's testing (how much testing they're doing, and how biased the sample is). If you're only testing a small # of people with severe symptoms, obviously the fatality rate will look really high. If you're testing a much wider section of the population, and testing people who aren't severely sick, the number will look lower. Some examples: - Iceland randomly tested people in the general population (no symptoms), they found ~1% of people tested positive, and half of those had no symptoms (and so probably wouldn't be tested). [1] - Italy tested an entire village (the village had a cluster of cases), 3% tested positive, of which half had no symptoms. - One professor used the Diamond Princess cruise ship as a baseline, and estimated anywhere from 0.025%-0.625% [2] - China had a fatality rate of 17% initially, which went down to 0.7% if you only consider symptom onset _after_ Feb 1st. [3] Of course, there are a lot of other factors, and it's possible that the rates end up in fact being really high, but there's an argument that we just don't know how many people are infected and fatality ends up being a lot lower then just dividing # of deaths by # of confirmed cases would have you believe. Just to be clear: even the lower case scenarios are really serious and worrying, and I'm definitely not in the "this is just another flu" camp. But there's a huge range of uncertainty here. [1] https://www.government.is/news/article/?newsid=f96a270c-66e8-11ea-945f-005056bc4d74 https://www.government.is/news/article/?newsid=f96a270c-66e8... [2] https://www.statnews.com/2020/03/17/a-fiasco-in-the-making-as-the-coronavirus-pandemic-takes-hold-we-are-making-decisions-without-reliable-data/ https://www.statnews.com/2020/03/17/a-fiasco-in-the-making-a... [3] https://www.cebm.net/covid-19/global-covid-19-case-fatality-rates/ https://www.cebm.net/covid-19/global-covid-19-case-fatality-...

cashsterling 7y ago

I can't stress enough how important this factor is... without widespread randomized testing of the population, we have no idea what the true infection rate is or how widespread the virus really is. Our current stats have a huge selection bias problem. This is why it is so important that we take social distancing, self hygiene, and shelter-in-place measures really seriously in order to protect those among us who may be more susceptible to severe infection. The silver lining: the more widespread the virus, and hence the number of asymptomatic cases... lower the actual the severity statistics are. i.e. we know "number of deaths", "number of hospitalizations", and "number of positive cases". Right now, when we calculate our various severity rates, we are putting "number of positive cases" in the denominator because we don't know the number of actual infections. There is an unknown multiplier (>= 1) relating positive cases to infections. All our severity statistics need to be divided by this unknown multiplier. But right now, since we don't know what it is... the responsible thing to do for reporting and policy decisions is assume it is 1 (worst case). It is not 1... it is greater than 1... we all know that. But how much is a tough question to answer properly without proper statistical sampling of the population. There are modelling studies and estimates that suggest value ranges for the multiplier, but I don't want to spread potentially false information on a public forum.

WalterSear 7y ago
It's not a silver lining: the number of serious cases remains the same and our ability to contain the epidemic is less effective.
- edanm 7y ago
  It is, because assuming that having the virus gives some immunity, then if we find out that 90% of people are asymptomatic, that implies that the number of cases we have right now won't go up much more (since many people have already had and recovered from Coronavirus).

deleted 7y ago

[deleted]