A month ago, I reported on @CDCgov's overestimate of true infections in the US.

It appears that last week, the CDC significantly lowered their estimates. It now closely matches covid19-projections.com's latest estimate of ~83M infected (~25% of the population).
My thread from last month is below, where I highlight the flaws in the CDC's original estimates (91M infections through November 2020 and a 7:1 infections to case ratio).

Their explanation:

"Since the previous update, CDC has received additional data about the proportion of persons with symptomatic illness who seek [..] testing services. The higher values of health-seeking behavior result in lower estimates of infections"

cdc.gov/coronavirus/20…
The CDC lowered the fraction of true COVID-19 infections that are reported by 40%, from 1 in 7.2 to 1 in 4.6.

Their new 95% uncertainty interval (1 in 4.0-5.4) is completely disjoint from their original interval (1 in 6.2-8.5).

They have yet to release an updated methodology.
Given this drastic change in results, it seems reasonable (to a non-academic like myself) that their original paper in "Clinical Infectious Diseases", a top infectious diseases journal, be retracted or at the very least, be corrected.

academic.oup.com/cid/advance-ar…
I hope this is not representative of the standards for paper acceptance across academia.

Otherwise, I would unfortunately not blame people for being skeptical of peer review/published results.

Trust in science should not be automatically given - it should be earned.
I have always tried to judge scientific work by the quality of the work itself, not by who wrote it.

Unfortunately, this has not been always true in academia, as some have accused me of "intellectual elitism" for simply critiquing CDC's work.

As I've said last time, I highly respect the work that the CDC does. And that's why I also hold their work to the same high standards.

I think the mentality of "don't question the experts because they must be right" can sometimes be detrimental and hinder the progress of ideas.

Of course, there should always be a balance (i.e. one cannot simply dismiss scientific results). And this balance can be a fine line.

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More from @youyanggu

27 Jan
Wed Jan 27 Weekly Vaccination Update:

Given no unforeseen supply issues, we estimate that the general public can receive the vaccine by April.

We also estimate over 60% of the US adult population will be fully vaccinated by June.

covid19-projections.com/path-to-herd-i… Image
These estimates are driven by data. In the past week, over 1 million doses were administered per day, a 20% week-over-week increase.

While there are news reports of anecdotal supply issues, this has not shown up in the data. If this changes, we will update accordingly. Image
Nationwide, new infections are decreasing quickly while vaccinations are steadily increasing.

But around 500k people are still being infected per day, double the summer peak.

The drop in infections is more likely due to a post-holiday slowdown rather than vaccinations. Image
Read 6 tweets
20 Jan
Jan 20 Weekly Update: New vaccinations (750k/day) are still increasing, but at a slower pace. 1st doses saw a 30% increase over last week, compared to 76% increase the week before.

We are the only site that tracks vaccine doses since December: covid19-projections.com/path-to-herd-i…
By state, Alaska and West Virginia lead the pack, with over 7% of the population receiving at least 1 dose.

In contrast, Nevada and Alabama have less than 3% of the population receiving at least 1 dose.

See more maps: covid19-projections.com/maps-infection…
As of today, over 14M people have received at least 1 dose, or 4.3% of the population.

36M doses have been distributed. Our "percent doses used" metric is under 50%.

Efficiency can be greatly improved.
Read 5 tweets
14 Jan
There appears to be an error on the CDC website.

The @CDCgov page currently claims 11M people have initiated COVID-19 vaccination, but the underlying data suggests that it's actually 11M *doses*.

This is quite misleading, and I hope this error is corrected ASAP.
I took some time to correct for this myself. Our vaccination page now breaks down administered doses into 1st & 2nd doses: covid19-projections.com/path-to-herd-i…

According to our estimates, 10M people (not 11.1M) have received at least one dose. Out of those 9M, 1.1M have received both doses.
After this adjustment, the current pace of new vaccinations is ~4M people per week. Even if we double that pace, it would take 9 months to vaccinate everyone.

As of now, ~15% of the daily doses given are used as a 2nd dose (114k / 747k). I expect this fraction to grow over time.
Read 5 tweets
12 Jan
New feature! We are now including vaccination status (according to @CDCgov) on all covid19-projections.com plots for every US state (and nationally).

Find out how quickly your state is vaccinating people here: covid19-projections.com/#view-us-infec…
For example, states like Florida and New York are quickly vaccinating more people than new infections, while states like California and Georgia are still lagging behind.
See my short thread from yesterday for more vaccination data + projections.

Read 4 tweets
7 Jan
Are high levels of existing COVID-19 population immunity in US counties associated with a lower infection rate in this current wave?

This thread contains my latest findings to this question.

Initial conclusion: No, there is practically no correlation.
The plot above shows the the percentage of the population infected before Sep 1 & after Sep 1 in each county (based on covid19-projections.com estimates).

The question is: can knowing the % infected before Sep 1 in a county predict the relative severity of this current wave?
When looking at all 3,000+ counties, the answer is no. There is practically no correlation (R^2 = 0.002) between the % infected before Sep 1 and after Sep 1.

So given a county, the COVID-19 prevalence before Sep 1 has no predictive value in determining the severity since Sep 1.
Read 26 tweets
5 Jan
Out of 137 US counties with >500,000 residents, the top five currently worst-hit counties are all in California.

We estimate 1 in 16 residents in those counties are currently infected with COVID-19.

See more in our new US County Summary page: covid19-projections.com/infections/sum…
So how does LA now compare to NYC at its peak?

We estimate NYC had 1 in 8 residents infected at its peak in March 2020. So LA is currently at half of NYC's peak.

Deaths are likely lower than half due to a lower IFR than in the spring.
Read 5 tweets

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