There are now multiple sources of evidence pointing to a very low true infection fatality rate, as low as 0.1% in some regions. Iceland has been testing a semi-random sample using PCR since early in the epidemic, and there have been several small antibody surveys in “hot spots” showing infection rates over 15%. You can also use CDC surveillance of flu-like illnesses to estimate the total number of infected nationwide; this morning I posted an analysis of this data estimating only 1 in 40 cases were detected in March, consistent with the Stanford results: https://fivetran.com/blog/covid-19-count
Covid-19 Antibody Seroprevalence in Santa Clara County, California
31–40 of 209 posts
Re: Covid-19 Antibody Seroprevalence in Santa Clara County, California
#32Add this to growing pile of evidence that this coronavirus is more widespread than most testing to date would suggest. How much more widespread still appears very unclear. There is a major ramping up of antibody testing happening right now, and multiple new tests being introduced, so we should have a better idea very soon. But the takeaway should be that this is a good thing. Every unknown case we uncover decreases t…
I don't follow your argument. If the epidemic is more widespread than initially thought, why do you assume that the effective transmission rate would potentially decrease? If anything, the transmission rate was higher than assumed and, due to the higher number of infections and how they spread exponentially,it would only ramp up. And additionally, there are reports of reinfections among covid19 patients who were foun…
There's good news and bad news: the good news is the more cases that are found from people who didn't know they had it, the less deadly the disease is. The bad news: if it's all over the place it will be really hard to stamp it out.
Re: Covid-19 Antibody Seroprevalence in Santa Clara County, California
#33"We recruited participants by placing targeted advertisements on Facebook aimed at residents of Santa Clara County..." I wonder if these ads mentioned the purpose of the study, or if that information was only given out after initial contact (I don't know enough about IRB requirements here). A concern is that this could cause a selection bias for people who suspected they had the virus. People may respond to such an a…
Why would this matter as long as they got a good geographical sampling? "We used Facebook to quickly reach a large number of county residents and because it allows for granular targeting by zip code and sociodemographic characteristics. We used a combination of two targeting strategies: ads aimed at a representative population of the county by zip code, and specially targeted ads to balance our sample for under-repre…
If part of the value for participants was to know whether they had antibodies, then those that had gone through a flu (or covid) would be more likely to respond. This means that the overall sample likely includes more people who had COVID than a true random sampling would.
Re: Covid-19 Antibody Seroprevalence in Santa Clara County, California
#34That is certainly alarming that it is so much more widespread than expected - it really highlights the failure of our controls against the virus and the importance of early testing. It I'd good news that this implies the death rate is less severe. However, a caveat is that antibody tests might have high rates of false positives, which would be a particularly large problem when very few people are actually positive. S…
Most signs so far suggest that the virus is basically uncontainable, short of everyone on the planet taking aggressive measures to stop it escaping China back in January or December.
How do you square that with the fact that there is no outbreak in any overseas Chinese community? Not Taiwan or Hongkong or Macau, nor in the epicenter of Italy (https://www.reuters.com/article/us-health-coronavirus-italy-...), nor San Francisco Chinatown (https://www.nytimes.com/2020/04/17/us/san-francisco-coronavi...)? All of these communities have far more ties to mainland China.
Re: Covid-19 Antibody Seroprevalence in Santa Clara County, California
#35Earlier quoted context omitted.
Based on the difference between CA and NY, I'd be willing to bet that it got here earlier, maybe in December.
You would have seen more reports in hospitals of interstitial pneumonia, as well as a higher YoY death rate during January.
The CDC is reporting an abnormally high pneumonia death rate in January, and it can’t be explained by confirmed flu cases:
https://www.cdc.gov/flu/weekly/#S6
Look carefully at the black and red graph after the phrase “mortality surveillance data”.
Re: Covid-19 Antibody Seroprevalence in Santa Clara County, California
#36Earlier quoted context omitted.
Based on the difference between CA and NY, I'd be willing to bet that it got here earlier, maybe in December.
California has 2X the population of New York. NY has more than 17X the number of deaths and while the daily deaths rate there is slowing it still far outpaces CA's daily rate. I don't know how you can look at those numbers and conclude the disease was spreading unchecked in California for multiple months.
Maybe a milder form of it came directly from Wuhan to CA, spreading like a bad flu. And then the version in NY came from Wuhan to Europe to NY, mutating along the way, and making it more deadly.
Re: Covid-19 Antibody Seroprevalence in Santa Clara County, California
#37"We recruited participants by placing targeted advertisements on Facebook aimed at residents of Santa Clara County..." I wonder if these ads mentioned the purpose of the study, or if that information was only given out after initial contact (I don't know enough about IRB requirements here). A concern is that this could cause a selection bias for people who suspected they had the virus. People may respond to such an a…
Yes, the ads accurately described the study. Several friends of mine participated (I live in Santa Clara County). Of course there is selection bias, which is why they make adjustments to make the sample better represent the population (see the abstract for details on this, or read the paper for all the details, there's well-established science behind these adjustments and it's up to the reviewers to be sure that they…
What adjustments were made to account for selection bias of the sort described? It's not covered in the paper, and "well-established science" certainly doesn't answer the question.
Re: Covid-19 Antibody Seroprevalence in Santa Clara County, California
#38That is certainly alarming that it is so much more widespread than expected - it really highlights the failure of our controls against the virus and the importance of early testing. It I'd good news that this implies the death rate is less severe. However, a caveat is that antibody tests might have high rates of false positives, which would be a particularly large problem when very few people are actually positive. S…
Note coauthor name "John Ioannidis". That gives the paper a healthy boost in my view.
Careful, though, because just being a critic doesn't mean he isn't susceptible to the same sorts of biases and issues that cause a lot of other medical papers to fail. I'm hoping he's on the paper because they ran it by him for a thumbs-up before submitting it.
Re: Covid-19 Antibody Seroprevalence in Santa Clara County, California
#39Add this to growing pile of evidence that this coronavirus is more widespread than most testing to date would suggest. How much more widespread still appears very unclear. There is a major ramping up of antibody testing happening right now, and multiple new tests being introduced, so we should have a better idea very soon. But the takeaway should be that this is a good thing. Every unknown case we uncover decreases t…
I don't follow your argument. If the epidemic is more widespread than initially thought, why do you assume that the effective transmission rate would potentially decrease? If anything, the transmission rate was higher than assumed and, due to the higher number of infections and how they spread exponentially,it would only ramp up. And additionally, there are reports of reinfections among covid19 patients who were foun…
"If the epidemic is more widespread than initially thought, why do you assume that the effective transmission rate would potentially decrease?"
Herd immunity. If testing is only detecting 1/50th of cases in NYC, for example, it means that there have been about 6M cases, or about 69% of NYC's population. That's basically the threshold where we'd expect to see the infection counts level off naturally.
Re: Covid-19 Antibody Seroprevalence in Santa Clara County, California
#40This is very strong evidence that the "realists" like Alex Berensen were correct. The shutdowns probably should end, while encouraging at-risk populations (mostly retired) to stay at home.