Saw this comment [1] on Reddit that outlines the limitations of the study well: This is the most poorly-designed serosurvey we've seen yet, frankly. It adverti

Saw this comment [1] on Reddit that outlines the limitations of the study well: This is the most poorly-designed serosurvey we've seen yet, frankly. It advertised on Facebook asking for people who wanted antibody testing. This has an enormous potential effect on the sample - I'm so much more likely to take the time to get tested if I think it will benefit me, and It's most likely to benefit me if I'm more likely to have had COVID. An opt-in design with a low response rate has huge potential to bias results. Sample bias (in the other direction) is the reason that the NIH has not yet released serosurvey results from Washington: We’re cautious because blood donors are not a representative sample. They are asymptomatic, afebrile people [without a fever]. We have a “healthy donor effect.” The donor-based incidence data could lag behind population incidence by a month or 2 because of this bias. Presumably, they rightly fear that, with such a high level of uncertainty, bias could lead to bad policy and would negatively impact public health. I'm certain that these data are informing policy decisions at the national level, but they haven't released them out of an abundance of caution. Those conducting this study would have done well to adopt that same caution. If you read closely on the validation of the test, the study did barely any independent validation to determine specificity/sensitivity - only 30! pre-covid samples tested independently of the manufacturer. Given the performance of other commercial tests and the dependence of specificity on cross-reactivity + antibody prevalence in the population, this strikes me as extremely irresponsible. This paper elides the fact that other rigorous serosurveys are neither consistent with this level of underascertainment nor the IFR this paper proposes. Many of you are familiar with the Gangelt study, which I have criticized. Nevertheless, it is an order of magnitude more trustworthy than this paper (both insofar as it sampled a larger slice of the population and had a much much higher response rate). It also inferred a much higher fatality rate of 0.37%. IFR will, of course, vary from population to population, and so will ascertainment rate. Nevertheless, the range proposed here strains credibility, considering the study's flaws. 0.13% of NYC's population has already died, and the paths of other countries suggest a slow decline in daily deaths, not a quick one. Considering that herd immunity predicts transmission to stop at 50-70% prevalence, this is baldly inconsistent with this study's findings. For all of the above reasons, I hope people making personal and public health decisions wait for rigorous results from the NIH and other organizations and understand that skepticism of this result is warranted. I also hope that the media reports responsibly on this study and its limitations and speaks with other experts before doing so. [1] https://www.reddit.com/r/COVID19/comments/g32wjh/covid19_antibody_seroprevalence_in_santa_clara/fnotu78/ https://www.reddit.com/r/COVID19/comments/g32wjh/covid19_ant...