The sample size is this non peer reviewed study is 79 vaccinated people (corrected, misread as 83 before) and completely lacks the statistical power to differentiate between vaccinated and unvaccinanted people.
Also as in the Provincetown study it's a convenience sample, meaning people who chose to be tested, and not a random sample of all infections. That likely biases the sample toward more severe infections since people with more severe symptoms are more likely to seek out testing.
Another big statistical issue in these studies (at least the Wisconsin one) is that they have truncated samples. People with high Ct values (higher Ct = harder to find virus) are eliminated from the comparison because it's not clear they can be considered "infected".
If one way that breakthrough infections manifest themselves is thru very low amounts of virus in some people, but then you eliminate people with very low viral loads from your comparison, you're sort of begging the question. Need to be careful in cases like these.
Here is a study from the UK with a MUCH larger sample size (~50K vaccinated people) that indeed finds vaccinated people carry lower viral loads.…
The study also avoids some of the selection bias issues discussed since it relies on a random sample, not just a convenience sample of those who happened to get tested because they had symptoms.

It is much more rigorous than e.g. the Wisconsin or Provincetown Bear Weak studies.
To throw a gauntlet down, a pretty simple test of whether news outlets like @nytimes actually care about getting the science right is if they report on this more rigorous UK study with >= fervor to the Provincetown study.
Seen discussion of the sample size in the UK study and it's worth pointing out that (although the overall sample size is very large) the number of *positives* is ~similar to the other studies. Note, however, that they do find a statistically significant result (p-value = 0.01).
And, again, this reflects a random sample of the entire UK population, which is >> more robust than a self-selected sample. The UK has done great work with large random samples like these; see also their work on Long COVID below, for instance.…

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More from @NateSilver538

30 Jul
The news is *not* that "vaccinated people easily spread the Delta variant". That reflects a gross misunderstanding of the CDC's evidence, abetted by imprecise and innumerate media coverage. See this thread below.

Vaccinated people are much less likely to become infected with COVID. *Conditional upon becoming infected*, there is some evidence to suggest they carry similar viral loads, but this evidence is quite uncertain, and viral loads do not necessarily equate 1:1 to transmission.
Of course it doesn't help when The New York Times takes some new (not yet public or peer-reviewed FWIW) study that says what I wrote above and frames it as some "harrowing new twist that upends everything we know about the coronavirus" or whatever.
Read 8 tweets
26 Jul
There were ~240,000 reported Delta cases in the US last week (and probably another ~2 million unreported Delta infections) but yeah let's keep those Delta-carrying Europeans out!
People from Slovenia are currently banned from entering the US whereas people from Malaysia are allowed, even though Malaysia currently has >10x as many cases per capita.
You could argue that it would be too much work for the US to constantly update the list of countries based on current conditions except the State Department already does *exactly that* for Americans traveling *to* those countries.…
Read 5 tweets
19 Jul
I think you'll see some places reimpose mask mandates and I think you'll see some fierce debates about school reopenings, but I'd be somewhat surprised if you see many COVID-related restrictions return in the US beyond that. (No idea about other countries.)
For one thing, it's not clear who the constituency for these restrictions would be. Vaccinated people are pretty safe and don't necessarily *need* them while unvaccinated people largely won't *want* them and may not abide by them.
For another, we're dealing with far different circumstances than earlier phases of the pandemic & I don't expect nearly as much consensus among public health experts on the desirability of restrictions. Even "Zero COVID" folks are now somewhat resigned.… Image
Read 4 tweets
2 Jul
This article is confusing. Experts make a great case that J&J recipients should get a booster.

But then it's said a new study—so far described only in a J&J press release!—addressed "some of those concerns". Weak basis for concluding no booster needed.… ImageImage
Another example of the logic I find confusing.

Sure, one-shot J&J may provide decent protection against Delta and better-than-decent against severe illness from Delta. But why wouldn't you want the VERY good protection you might get from an mRNA booster?… Image
One consistent lesson from COVID is you should trust the experts' evidence (e.g. studies that show mRNA boosters really boost protection in people who got the AZ vaccine) more than their proscriptive advice (e.g. "I wouldn't get a booster) when the two are in conflict.
Read 4 tweets
29 Jun
Kinda seems like Yang's endorsement of Garcia as his #2 mattered here. She gains a lot of ground and overtakes Wiley when Yang is eliminated.

Note that these results are preliminary; does not include absentee ballots. ImageImage
This is another key observation. About 25% of ballots were exhausted. Always fill out all your choices when participating in a ranked-choice election.
Another question: Given that Garcia barely edged out Wiley in the penultimate round before nearly catching Adams, does that mean Wiley has a path *too* once absentees are added?

My guess is Wiley has a path, but it's pretty unlikely one (see next tweet).

Read 6 tweets
13 Jun
So the thesis here is that Walensky follows the medical science, but actually this is bad and the CDC should tell weird little lies to people?…
I guess you can steel-man this by saying "behavioral science is science too!". I strongly agree.

But i) the public health community's instincts for behavioral science have been poor;
ii) Behavioral science would suggest an agency being less honest with people has consequences.
If you want to say "follow the *behavioral* science, *too*!", that's great!

But some of the people cited in this article have been quite hostile to behavioral scientists (sociologists, economists, political scientists, etc.) when they've tried to contribute their own expertise.
Read 4 tweets

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