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Youyang Gu Profile picture
Youyang Gu
@youyanggu
Data Scientist. Creator of https://t.co/ByO92M3ceQ and https://t.co/k9yZN1fORq. Presenter of unbiased takes. Realist. @MIT '15.
11 subscribers
Aug 5, 2021 • 6 tweets • 3 min read
People were worried cases would spike further when the UK lifted almost all remaining restrictions in July. The opposite happened.

We must acknowledge that restrictions aren't all that effective in Western countries.

(Except Australia, who just entered their 6th lockdown) It's interesting that some experts would rather question the accuracy of the data than acknowledge this reality.
Jul 22, 2021 • 4 tweets • 2 min read
Thanks @ScottGottliebMD! On data, research & messaging, there’s lots of room for improvement at the CDC.

For modeling, they were right in enlisting @reichlab to run Forecast Hub: cdc.gov/coronavirus/20…

They’ve crowdsourced 30+ teams for weekly updates.

Of course, the modeling isn’t perfect & never will be. But this ensemble of forecasts coming from 250+ researchers has helped add clarity for many over the past year.

The CDC deserves credit for taking a conscious, hands-off approach on this.

technologyreview.com/2021/05/28/102…
Jul 1, 2021 • 4 tweets • 3 min read
On its last model update on March 5, 2021, covid19-projections.com projected that 180 million people in the US will be vaccinated by July 1 (1+ dose).

Today, July 1, @CDCgov reported that the US surpassed 180M people vaccinated.

Not all models are bad.

covid19-projections.com/path-to-herd-i… Image Since I began making vaccination projections in Dec 2020, I have consistently predicted a return to normal by Summer 2021.

Some said it was too optimistic, others too pessimistic.

It appears that as of this week, all states (minus HI) are fully reopen.

ImageImage
Jun 30, 2021 • 5 tweets • 2 min read
South Dakota has a vaccination rate of 50% (1+ dose). Maine is at 66%. So is Maine better protected?

Not quite. If you factor in immunity from natural infection, SD has a total population immunity of ~70%, while ME is at ~62%.

I created a calculator: docs.google.com/spreadsheets/d… Many existing immunity estimates only look at a single metric: vaccination rate. But there are two main issues:

1) Not all vaccinated individuals are fully immune
2) They do not take into account acquired natural immunity

This calculator attempts to correct for this.
Jun 22, 2021 • 13 tweets • 6 min read
I believe income inequality is the single best predictor of total Covid deaths in the US.

Not income, but income *inequality*. The R^2 is surprisingly high: 0.35.

Thanks to @joe_sill, I was able to look at over 40 different variables, and expands on my analysis from last month. It's honestly shocking how correlated the Gini coefficient, a measure of inequality in wealth distribution in a state, is with total Covid deaths.

No other predictor I've seen comes close.

Props to @joe_sill for the finding and an excellent dataset:

May 25, 2021 • 18 tweets • 7 min read
Is containing COVID-19 a requirement for preserving the economy? My analysis suggests: probably not.

In the US, there is no correlation between Covid deaths & changes in unemployment rates.

However, blue states are much more likely to have higher increases in unemployment.

🧵 Image We can dive deeper by looking at levels of restrictions in each state, using the Oxford Covid-19 Government Response Tracker (OxCGRT).

More restrictions in a state is NOT correlated with fewer COVID-19 deaths.

However, more restrictions IS correlated with higher unemployment. ImageImage
May 18, 2021 • 12 tweets • 4 min read
Dr. Fauci said this week that racism led to unacceptable disparities in health for minority groups, "especially African Americans, Hispanics & Native Americans".

Time & time again, Asian Americans are overlooked & left out.

A 🧵 on model minority myth.

May is Asian American & Pacific Islander (AAPI) Heritage Month.

I want to take this thread to address something that means a lot to me personally:

The myth of the model minority and why everyone, intentionally or unintentionally, can fall for the myth.
May 13, 2021 • 15 tweets • 4 min read
Are we still in a pandemic?

I put together a model this week to estimate current excess deaths. Here's what I concluded:

For 32 US states, the answer is YES.

For the remaining states, current all-cause deaths are likely below the upper bound threshold for excess deaths. 🧵 My model estimates that 8 states still have excess deaths that are more than 10% above the upper bound threshold:

Michigan (30% excess!), Indiana, New Mexico, Louisiana, Illinois, Oregon, Texas, and Nevada

The data suggests that these states are still amidst a pandemic.
May 11, 2021 • 12 tweets • 4 min read
In the weeks ahead, we'll probably see more politicized debates about mask mandates. But let's first look at the data!

Below are COVID-19 cases over the past months for states that kept vs dropped mask mandates.

Cases are dropping regardless of the presence of mask mandates. 🧵 The 5 states that lifted their mask mandates in February and March (IA, ND, MT, MS, TX) also saw a similar continued decline in cases, even more so than masked states.

(the bump in early Mar was due to the Texas power crisis)
Mar 12, 2021 • 13 tweets • 4 min read
This past week I’ve made my last daily update to covid19-projections.com. Thank you to everyone who visited the site over the past year.

I’m also taking a break from Twitter. It's been a great resource but can also serve as an echo chamber at times.

Some final thoughts 🧵(1/13) Our final update shows that roughly 100M people, or 30% of the US population, have been infected by end of Feb.

Our vaccination estimates show that around 2/3 of the US 18+ population will be vaccinated by June. A return to normal will follow soon after.

covid19-projections.com/path-to-herd-i…
Mar 11, 2021 • 23 tweets • 8 min read
We must stop ranking states by the percent of the population they've vaccinated.

It unfairly favors states that prioritize speed of vaccination at the expense of protecting their vulnerable population, & deepens systematic inequalities that favor wealthy states.

Hear me out 🧵 Backstory: Experts spent weeks in Dec debating & rejecting the idea of an age-based vaccine distribution which favors speed over equity.

It resulted in the CDC recommending that people aged 16-64 with underlying medical conditions be included in Phase 1.

cdc.gov/coronavirus/20…
Mar 10, 2021 • 19 tweets • 7 min read
Here's a very interesting thread where several academic Twitter heavyweights debate the Facebook censorship of a @WSJ op-ed by Johns Hopkins public health professor @MartyMakary.

A 🧵 on my thoughts on censorship (tldr; it's a slippery slope).

First of all, no one is disagreeing that Dr. Makary's piece has very questionable assumptions and claims. Experts widely denounced it when it came out. I've also expressed my disapproval:



Here's the article in question: wsj.com/articles/well-…
Mar 9, 2021 • 7 tweets • 3 min read
How to be like Connecticut:

1) Be the richest state in the country
2) Vaccinate its wealthy, white residents
3) Announce "we've protected the vulnerable"
4) Drop all business capacity restrictions
5) Receive praise from public health experts

23% of white residents in CT over age of 65 have been fully vaccinated, compared to just 10% of black & hispanic residents and 15% of Asian residents.

Source: data.ct.gov/stories/s/CoVP…

It's disappointing to see respected experts moving goalposts and ignoring inequity.
Mar 3, 2021 • 7 tweets • 3 min read
We surpassed 1M new vaccinations/day for the 1st time this week. @WhiteHouse announced that there'll be enough vaccines for everyone by May, 2 months earlier than expected.

But in fact, this is quite expected. Many have been saying this since January. 🧵

Don't get me wrong, it's great news to hear that we are still on track.

Here is the latest vaccination progress and our projections for the next few months.

covid19-projections.com/path-to-herd-i… ImageImage
Mar 2, 2021 • 6 tweets • 2 min read
Here's one danger of data:

Child abuse cases are way down during this pandemic. Does that mean there's less child abuse happening? Of course not.

If schools are closed and children are forced to stay home with their abusers, who's going to report them? In the words of @VPrasadMDMPH:

"Many of you support the US school closures bc of availability bias. You see the harms of the virus, but not the harms of closure."

Follow him and @apsmunro for good insights on schools.

Feb 25, 2021 • 5 tweets • 3 min read
Thu Feb 25 Vaccination Update - Two main takeaways from this past week:

1) There were fewer new vaccinations than a month ago
2) More 2nd doses were given than 1st doses

covid19-projections.com/path-to-herd-i… The winter storm in the South had an impact, but the trend wasn't looking great before the storm either.

Pretty much all states already used up the majority of their doses.

However, there's an increase of 13M newly distributed doses over the last two days, so that's promising.
Feb 24, 2021 • 11 tweets • 3 min read
When can we return to normal? Forget about "herd immunity".

Below is my estimate for the number of susceptible individuals over time, as a proportion of the US population.

Looking at this graph, what is the best point to go back to normal? Christmas? Fall? Or Summer?

🧵 By summer, everybody who wants a vaccine will be able to get one. The vulnerable population will long have been able to receive their shots. Hospitalizations & deaths will be at negligible levels.

Normality will happen... with or without herd immunity.

Feb 23, 2021 • 7 tweets • 3 min read
Unfortunately this @nytimes model uses unrealistic assumptions, like "80% of the population is ultimately fully vaccinated".

Even if *every* adult is vaccinated, that's still not 80% of the population. And we haven't even factored in vaccine hesitancy.

nytimes.com/interactive/20… Rather than clearly highlighting this bold assumption in the article, it's buried at the bottom as a footnote.

At what point do unrealistic model assumptions become misleading? Does the science support immunity lasting indefinitely? Or 80% of Americans getting fully vaccinated?
Feb 22, 2021 • 16 tweets • 5 min read
A @CDCgov report in Jan concluded that "university counties with in-person instruction experienced a 56% increase in incidence".

They only examined 21 days before/after classes start.

Since then, those counties saw a much lower incidence vs counties w/remote instruction.

🧵 You can see above that counties with in-person instruction had a ~50% higher incidence in the weeks after classes start than remote counties, consistent with the CDC report.

But during the peak in Dec/Jan, counties w/in-person instruction actually had a ~50% *lower* incidence.
Feb 18, 2021 • 12 tweets • 4 min read
I've seen many news articles cite that "the UK variant could be the dominant strain by March". This is emphasized by @CDCDirector.

While this will likely to be the case, this should not be an automatic cause for concern. Cases could still remain contained.

Here's how: 🧵 One of @CDCgov's own models has tracked the true decline in cases quite accurately thus far.

Their projection shows that the B.1.1.7 variant will become the dominant variant in March. But interestingly... there's no fourth wave. Cases simply level out:

cdc.gov/mmwr/volumes/7…
Feb 17, 2021 • 15 tweets • 7 min read
Which metric is a better predictor of the severity of the fall surge in US states?

1) Margin of Democrat victory in Nov 2020 election
or
2) % infected through Sep 1, 2020

Can you guess which plot is which? The left plot is based on the % infected through Sep 1, 2020. You can see that there is very little correlation with the % infected since Sep 1.

However, there is a *strong* correlation when using the margin of Biden's victory (right).

Infections % from covid19-projections.com.