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Mike Hoerger, PhD MSCR MBA Profile picture
Mike Hoerger, PhD MSCR MBA
@michael_hoerger
Expert in weighing medical evidence, cancer, COVID forecasting & mitigation, health disparities, financial analytics. 120 publications. PhD program director.
45 subscribers
Apr 9 • 5 tweets • 2 min read
The NIH Clinical Center drops universal masking after 5 months of protecting patients, family, & staff.

Wastewater-derived estimates indicate 2.79 million Americans are getting Covid per week AND top actuaries suggest an American dies of Covid every 3 minutes.

🧵1/5 Masks are optional beginning April 11. Staff will mask on request. These are the current wastewater-derived estimates of transmission.

2.79 million Covid infections/week in the U.S. in the current high "lull."
🧵2/5
Apr 7 • 4 tweets • 2 min read
1) PMC COVlD Dashboard, April 7, 2025 (U.S.)

🔹1 in 120 actively infectious
🔹1 in 3 chance of exposure in a room of 50
🔹2.8 million weekly infections
🔹>140,000 resulting LC cases from the week's infections
🔹>1,000 deaths resulting from the week's infections Current Levels for Apr 7, 2025 % of the Population Infectious 0.8% (1 in 120) New Daily Infections 399000 New Weekly Infections 2793000 Resulting Weekly Long COVID Cases 140,000 to 559,000 Resulting Weekly Excess Deaths 1,000 to 1,700 Monthly Forecast Average % of the Population Infectious 1.0% (1 in 105) Average New Daily Infections 455766.6667 New Infections During the Next Month 13673000 Resulting Monthly Long COVID Cases 684,000 to 2,735,000 Resulting Monthly Excess Deaths 4,900 to 8,100 Running Totals Infections Nationwide in 2025 55591000 Average Number of... 2) Watch this video to understand how we use excess death data from one of the world's largest reinsurers to estimate how this week's infections will result in >1,000 deaths.
Mar 31 • 5 tweets • 2 min read
🧵1 of 5
PMC Dashboard, March 31, 2025 (U.S.)

🔹800-1,400 deaths expected to result from this week's infections (new stat, see video next Tweet)
🔹100,000+ Long Covid conditions to result from this week's infections
🔹1 in 142 actively infectious todayCurrent Levels for Mar 31, 2025 % of the Population Infectious 0.7% (1 in 142) New Daily Infections 337000 New Weekly Infections 2359000 Resulting Weekly Long COVID Cases 118,000 to 472,000 Resulting Weekly Excess Deaths 800 to 1,400 Monthly Forecast Average % of the Population Infectious 0.8% (1 in 120) Average New Daily Infections 397233.3333 New Infections During the Next Month 11917000 Resulting Monthly Long COVID Cases 596,000 to 2,383,000 Resulting Monthly Excess Deaths 4,300 to 7,100 Running Totals Infections Nationwide in 2025 52303000 Average Number of ... 🧵2 of 5
PMC Dashboard, March 31, 2025 (U.S.)

This video explains U.S. COVID excess death statistics, which we have incorporated into the dashboard.

Mar 31 • 6 tweets • 3 min read
PMC Update on #ExcessDeaths

🔥109,000-175,000 people in the U.S. are expected to die as a result of COVID in 2025, based on estimates derived from Swiss Re
🔥COVID deaths expected to be on par with lung cancer in the U.S. in 2025
🔥Death data added to the dashboard 2) Full video links to learn more about COVID #ExcessDeaths in the U.S.

Dashboard page (presently featured): pmc19.com/data
Downloadable file: pmc19.com/data/deaths033…
Veed platform: veed.io/view/558039f4-…
Mar 24 • 5 tweets • 2 min read
PMC Dashboard, Mar 24, 2025 (U.S.)
🧵1/5

🔹3 million new weekly infections in a persistent "lull" of substantial transmission
🔹1 in 107 (0.9%) of the population actively infectious
🔹1 in 3 regions in high/very high transmission (16 states and DC)Heat map of transmission, described in Tweet PMC Dashboard, Mar 24, 2025 (U.S.)
🧵2/5

We have had a steady state of about a half million infections the past several weeks. That's over 50 million estimated infections so far in 2025.

In a room of 40-50 people, there's a 1-in-3 chance of exposure if no testing/isolation.Current Levels for Mar 24, 2025 % of the Population Infectious 0.9% (1 in 107) New Daily Infections 446000 New Weekly Infections 3122000 Resulting Weekly Long COVID Cases 156,000 to 624,000 Monthly Forecast Average % of the Population Infectious 1.0% (1 in 96) Average New Daily Infections 496566.6667 New Infections During the Next Month 14897000 Resulting Monthly Long COVID Cases 745,000 to 2,979,000 Running Totals Infections Nationwide in 2025 50757000 Average Number of Infections Per Person All-Time, U.S. 3.708526284 How Does Risk Increase with More Social Co...
Mar 11 • 25 tweets • 8 min read
1) 5-yr Anniversary of the WHO Pandemic Declaration

🔥10 waves
🔥Covid mortality rivals lung cancer
🔥8 infections/person by 2030
🔥Long Covid as catastrophic
🔥Death trajectories becoming complex
🔥"During Covid" as anti-science rhetoric
🔥Serious ppl take Covid seriously
🧵 2) Wastewater-derived estimates of case rates show international consensus 20-26% of populations got Covid during the peak 2 months of the 2023-24 winter wave in the U.S., Canada, and the U.K.
Feb 26 • 4 tweets • 2 min read
1) Mardi Gras 2020 was 5 years ago today. ⚜️

It was before the pandemic declaration, before the federal government recommended masking.

COVlD spread quickly through New Orleans, leading to one of the highest mortality rates per capita in the U.S.... Timeline showing Mardi Gras 2020 just 4 days before the first known reported death of C19 in the U.S. Note. "Peak" diagnoses refers to the peak of the 1st wave. 2) New Orleans service workers were disproportionately hit by the early pandemic. Many died. Many developed #LongCOVID at the time or have now through repeat infections. Many have switched to other sectors....

Feb 17 • 5 tweets • 2 min read
1) PMC COVlD Dashboard, Feb 17, 2025 (U.S.)

🔥1 in 72 actively infectious
🔥Sustained high transmission
🔥30 states in high/very high transmission (CDC)
🔥3x the transmission of Feb 2021
🔥668,000 daily infections
🔥Only 1 in 28 cases reportedGraph shows 10 waves of the pandemic. Tables summarized partially in post. Additionally, transmission is higher than during 59% of the pandemic. How Does Risk Increase with More Social Contacts? Number of People | Chances anyone is infectious 1 1.4% 2 2.8% 3 4.1% 4 5.5% 5 6.8% 6 8.1% 7 9.4% 8 10.6% 9 11.9% 10 13.1% 15 19.0% 20 24.5% 25 29.7% 30 34.4% 35 38.9% 40 43.0% 50 50.5% 75 65.2% 100 75.5% 300 98.5% 2) PMC COVlD Dashboard, Feb 17, 2025 (U.S.)

This is a mid-sized wave, meaning substantial transmission. Notice that transmission remains steady at high rates.

Expect steady or slightly declining transmission, unless the real-time data are retroactively corrected.Two graphs, showing year-over-year transmission and the forecast, summarized in the post.
Feb 11 • 7 tweets • 3 min read
1) A lot of high-risk/aware patients I talk to -- mostly getting cancer treatment -- tend to protect themselves from infection by staying home more.

In the work we do, we help patients to understand that a well-fitting high-quality mask can allow them to attend events safely. 2) These are some tips for finding a well-fitting mask among common options in the U.S. and Canada.

Jan 28 • 9 tweets • 3 min read
1) PMC COVID Dashboard for the Week of Jan 27, 2025 (U.S.)

🔹1 in 108 actively infectious
🔹3.1 million weekly infections
🔹>150,000 weekly resulting Long Covid conditions Current Levels for Jan 27, 2025 % of the Population Infectious 0.9% (1 in 108) New Daily Infections 443,000 New Weekly Infections 3,101,000 Resulting Weekly Long COVID Cases 155,000 to 620,000 Monthly Forecast Average % of the Population Infectious 0.9% (1 in 106) Average New Daily Infections 452,933 New Infections During the Next Month 13,588,000 Resulting Monthly Long COVID Cases 679,000 to 2,718,000 Running Totals Infections Nationwide in 2025 18,779,000 Average Number of Infections Per Person All-Time, U.S. 3.60 There is more COVID-19 transmission today than during 41.9% of the pan... 2) We predicted the wave peak would be 0.8 to 1.3 million across various forecasts. We presently have it at 0.9-1.0 million, though retroactive corrections can change that. The WHN also runs an excellent model, with a peak estimated at 1.3 million.
whn.global/estimation-of-…
Jan 20 • 5 tweets • 6 min read
1) PMC COVID-19 Forecast for Jan 20, 2025 (U.S.)

If we are lucky, the 10th wave has peaked, likely in the 0.9-1.1 million daily infections range, barring significant retroactive corrections.

Over the next month, we should still see about 14 million infections, resulting in 700K to 2.8 million new conditions and enduring symptoms under the umbrella of #LongCOVID. This is simply your reminder than transmission remains high on the back on of a wave.

Regarding the peak, there were huge retroactive downward corrections, especially in Oregon. The CDC data originally showed one of the largest waves there all-time, and then corrected it to say a complete lull the whole time. Once the Biobot data get updated, we may see the peak date change by a week, or jump a bit higher than what you see in the main figure.

What you see in the far end of the forecast is unlikely to be a "high lull," but rather an average between a low lull versus a sustained post-peak haunch of lingering transmission. So, keep an eye on the data. If you're putting off a non-urgent medical appointment, we could get into relatively lower transmission in the next 4-8 weeks. What has me concerned is a sneak-peek of @jlerollblues's long-term forecast indicating a clear possibility of an earlier "mid-year" wave than usual, perhaps even in April. We're still getting pretty lucky on the viral evolution front, but the longer that persists, in absent of major policy change, the bigger the wave we could get. It's a very important time to stay tuned.

Caveats: No data from Biobot in weeks (20% model weight). The California wildfires and pending severe storms in the Deep South are wildcards for transmission. School-based transmission could pick up, but to get a higher peak, transmission would need to pick up much faster in the South and West than in the Midwest and North (unlikely).

In the report, I note that PMC will persist even if the CDC drops or scales back their surveillance program. Also, the most two recent "odd" waves have helped clarify how to handle historical data, and a minor update to the model should help with future atypical waves. If time permits, we will fine-tune those changes further, but there are always more battles on the Covid front than we're able to fight. We also provide a link and light commentary on our recent pre-print showing what our current case estimation model for estimating present/prior daily infections has performed well, and why a lot of other models (BNO, JP, CDC) are underestimates.

Info for new readers:

For those unfamiliar with the PMC model, find full weekly reports for the past 1.5 years at pmc19.com/data

The models combine data from IHME, Biobot, and CDC to use wastewater to estimate case levels (r = .93 to .96) and forecast levels the next month based on typical levels for that date and recent patterns of changes in transmission the past 4 weeks.

Our work has been cited in top scientific journals and media outlets, which are fully sourced in a detailed technical appendix at pmc19.com/data/PMC_COVID…

Examples include JAMA Onc, JAMA-NO, BMC Public Health, Time, People, TODAY, the Washington Post, the Institute for New Economic Thinking, Salon, Forbes, the New Republic, Fox, CBS, NBC, and CNN. See pgs 11-13 at the above link.

#MaskUp #VaxUp #CleanTheAir #RapidTestCurrent Levels for Jan 20, 2025 % of the Population Infectious 1.1% (1 in 87) New Daily Infections 547,000 New Weekly Infections 3,829,000 Resulting Weekly Long COVID Cases 191,000 to 766,000 Monthly Forecast Average % of the Population Infectious 1.0% (1 in 102) Average New Daily Infections 466,700 New Infections During the Next Month 14,001,000 Resulting Monthly Long COVID Cases 700,000 to 2,800,000 Running Totals Infections Nationwide in 2025 15,281,000 Average Number of Infections Per Person All-Time, U.S. 3.59 How Does Risk Increase with More Social Contacts? Number of People | Ch... 2) Here is the issue of Oregon I noted, with the "disappearing surge" in the CDC data. By that, I don't mean a surge that declined quickly. I mean, the CDC saying there was a huge surge in OR and then saying it was a lull the whole time. Baffling.

Jan 6 • 5 tweets • 5 min read
1) PMC COVID-19 Dashboard, Jan 6, 2025 (U.S.)

📈1 in 49 people actively infectious
🔥Nearly 1 million daily infections
🎲About a 50-50 chance someone has COVID in a large class if typical risk and no testing/isolating
🏥300,000+ new Long Covid conditions per week

The infections are likely minor underestimates. AZ and OR did not report this week. They were surging, so the lack of data brings down the average. As well, the model gives 80% weight to CDC wastewater data and 20% weight to Biobot, but Biobot took the week off, so this is dependent on observed changes in the CDC data.

It would be wise to add multiple imputation into the model to account for all the non-random missingness during surges, but I won't likely get to that anytime soon.

The peak is looking more and more like 1.4 million daily infections, but I wouldn't be surprised if it's earlier than shown and more like 1.3 million, based on the pattern of retroactive data corrections last winter. If the real-time data really stink, it could come in closer to 1.0-1.1 million. To top 1.6 million, we would probably need some serious immune escape that at present I just don't see happening. However, in past winters, transmission was declining nationally in early/mid January, and back-to-school is a wild card.

Info for new readers:

For those unfamiliar with the PMC model, find full weekly reports for the past 1.5 years at pmc19.com/data

The models combine data from IHME, Biobot, and CDC to use wastewater to estimate case levels (r = .93 to .96) and forecast levels the next month based on typical levels for that date and recent patterns of changes in transmission the past 4 weeks. Our work has been cited in top scientific journals and media outlets, which are fully sourced in a detailed technical appendix at pmc19.com/data/PMC_COVID…

Examples include JAMA Onc, JAMA-NO, BMC Public Health, Time, People, TODAY, the Washington Post, the Institute for New Economic Thinking, Salon, Forbes, the New Republic, Fox, CBS, NBC, and CNN. See pgs 11-13 at the above link.

We will have a pre-print out in the next week or so documenting very compelling evidence for the validity of using wastewater to estimate case rates. Forecasting is challenging in the context of the current viral evolution, but the real-time estimates of cases are impressively accurate to the best we can evaluate it.

#MaskUp #VaxUp #CleanTheAir #RapidTestCurrent Levels for Jan 6, 2025 % of the Population Infectious 2.1% (1 in 49) New Daily Infections 980,000 New Weekly Infections 6,860,000 Resulting Weekly Long COVID Cases 343,000 to 1,372,000 Monthly Forecast Average % of the Population Infectious 2.7% (1 in 38) Average New Daily Infections 1,272,833 New Infections During the Next Month 38,185,000 Resulting Monthly Long COVID Cases 1,909,000 to 7,637,000 Running Totals Infections Nationwide in 2025 5,468,000 Average Number of Infections Per Person All-Time, U.S. 3.55 How Does Risk Increase with More Social Contacts? Number of people |... 2) PMC COVID-19 Dashboard, Jan 6, 2025 (U.S.)

We're in the 10th wave of the pandemic (1st graph), and transmission this year has picked up atypically late, while coming on strong (2nd graph).Two graphs, summarized in tweet
Jan 3 • 4 tweets • 1 min read
📢Clean Air Advocates📢

I recently learned of a new strategy to get more clean indoor air to people's homes. I don't believe I've heard anyone mention this on here, but please add if you have made inroads.
1/ Last August, I was surprised to learn that Entergy, our regional energy company, was giving away free HEPA filters to customers.

This was surprising to me. Why would an energy company do this?
2/
Dec 20, 2024 • 8 tweets • 3 min read
x.com/i/article/1870… 2) This is one of the better scenarios I noted, with national levels coming in at about 3.33. Unfortunately, the rise was a little lower than anticipated only because transmission slowed in the west. Not uniform, so lots of uncertainty.

Dec 16, 2024 • 8 tweets • 10 min read
PMC COVID-19 Dashboard, Dec 16, 2024
🧵1 of 8

🔹1 in 64 (1.6%) actively infectious in the U.S.
🔹750,000 new daily infections and rising
🔹Highest % increase in transmission in nearly 3 years
🔹10th wave is the "silent surge," coming on late out of nowhere

The video will walk you through each of the graphs on the dashboard and covered in this thread.

Info for new readers:

For those unfamiliar with the PMC model, find full weekly reports for the past 14+ months at pmc19.com/data

The models combine data from IHME, Biobot, and CDC to use wastewater to estimate case levels (r = .93 to .96) and forecast levels the next month based on typical levels for that date and recent patterns of changes in transmission the past 4 weeks.

Our work has been cited in top scientific journals and media outlets, which are fully sourced in a detailed technical appendix at pmc19.com/data/PMC_COVID…

Examples include JAMA Onc, JAMA-NO, BMC Public Health, Time, People, TODAY, the Washington Post, the Institute for New Economic Thinking, Salon, Forbes, the New Republic, Fox, CBS, and NBC. See pgs 11-13 at the above link.

We will have a pre-print out in the next month documenting very compelling evidence for the validity of using wastewater to estimate case rates. Forecasting is challenging in the context of the current viral evolution, but the real-time estimates of cases are impressively accurate to the best we can evaluate it. PMC COVID-19 Dashboard, Dec 16, 2024
🧵2 of 8

🔹10th wave taking off (U.S.)
🔹5 million infections expected this week
🔹>250,000 post-infection conditions (#LongCovid) expected to develop from this week's infections
🔹Higher transmission than 73% of the pandemic

Info for new readers (as noted in Tweet 1):

For those unfamiliar with the PMC model, find full weekly reports for the past 14+ months at pmc19.com/data

The models combine data from IHME, Biobot, and CDC to use wastewater to estimate case levels (r = .93 to .96) and forecast levels the next month based on typical levels for that date and recent patterns of changes in transmission the past 4 weeks.

Our work has been cited in top scientific journals and media outlets, which are fully sourced in a detailed technical appendix at pmc19.com/data/PMC_COVID…

Examples include JAMA Onc, JAMA-NO, BMC Public Health, Time, People, TODAY, the Washington Post, the Institute for New Economic Thinking, Salon, Forbes, the New Republic, Fox, CBS, and NBC. See pgs 11-13 at the above link.

We will have a pre-print out in the next month documenting very compelling evidence for the validity of using wastewater to estimate case rates. Forecasting is challenging in the context of the current viral evolution, but the real-time estimates of cases are impressively accurate to the best we can evaluate it.Current Levels for Dec 16, 2024 % of the Population Infectious 1.6% (1 in 64) New Daily Infections 748,000 New Weekly Infections 5,236,000 Resulting Weekly Long COVID Cases 262,000 to 1,047,000 Monthly Forecast Average % of the Population Infectious 2.5% (1 in 41) Average New Daily Infections 1,178,167 New Infections During the Next Month 35,345,000 Resulting Monthly Long COVID Cases 1,767,000 to 7,069,000 Running Totals Infections Nationwide in 2024 242,424,000 Average Number of Infections Per Person All-Time, U.S. 3.50 There is more COVID-19 transmission today than during 73.3% of th...
Oct 22, 2024 • 4 tweets • 4 min read
PMC COVID-19 Forecasting Model, Oct 21, 2024
🧵1 of 4

Every indication is that the 10th U.S. Covid wave is on the way. Within 2 weeks, expect transmission to be meaningfully higher.

Current estimates from PMC:
🔹1 in 115 actively infectious
🔹Higher transmission than during 43% of the pandemic
🔹Nearly 3 million weekly infections

These estimates are high in the absolute sense, but low relative to the recent summer wave and likely winter surge.

The CDC data show transmission increasing in the Northeast, and a slowing of the decline in transmission elsewhere. Biobot data also show flattening transmission. The raw CDC and Biobot wastewater data are delayed >1 week. Walgreens shows positive cases, testing, and positivity ratios flattening and is delayed only 1 day.

For those unfamiliar with the model, find full weekly reports for the past 14+ months at pmc19.com/data

The models combine data from IHME, Biobot, and CDC to use wastewater to estimate case levels (r = .93 to .96) and forecast levels the next month based on typical (median) levels for that date and recent patterns of changes in transmission the past 4 weeks.

Our work has been cited in top scientific journals and media outlets, which are fully sourced in a detailed technical appendix at pmc19.com/data/PMC_COVID…

Examples include JAMA Onc, JAMA-NO, BMC Public Health, Time, People, TODAY, the Washington Post, the Institute for New Economic Thinking, Salon, Forbes, the New Republic, Fox, CBS, and NBC. See pgs 10-11 at the above link.GRAPH Shows forecasted entry into a 10th Covid wave. TABLES Current Levels for Oct 21, 2024 % of the Population Infectious 0.9% (1 in 115) New Daily Infections 414,000 New Weekly Infections 2,898,000 Resulting Weekly Long COVID Cases 145,000 to 580,000 Monthly Forecast Average % of the Population Infectious 1.3% (1 in 76) Average New Daily Infections 627,600 New Infections During the Next Month 18,828,000 Resulting Monthly Long COVID Cases 941,000 to 3,766,000 Running Totals Infections Nationwide in 2024 225,097,000 Average Number of Infections Per Person All-Time, U.S. 3.46 How Does ... PMC COVID-19 Forecasting Model, Oct 21, 2024
🧵2 of 4

These graphs show the forecast for changes in transmission over the next month.

The first graph shows year-over-year transmission. The 2nd focuses on the most recent year. Within a month, expect to see 0.7 to 1.0 million daily infections, if the assumptions of the model hold.

If lucky, we could get a slightly longer "lull" than what the model shows. The model likely underestimates the true value for the recent summer peak because many children were infected while going back to school, in fact, the highest peak at that time period all-time. Wastewater underestimates child infections ("contributions" correlate highly with body weight, so it takes four ill 50 lb kids to show up as one ill 200 lb adult). In underestimating the peak, transmission also fell more rapidly than anticipated post-peak. To the extent we underestimated the magnitude of the peak, there may be fewer than anticipated infections the next two weeks and a longer lull.

If you look at the first graph, however, you will see a clear patterns of escalating transmission in November, so it's more a matter of how quickly the situation will worsen than whether it will worsen.

During this relative "lull," it's an excellent time to stock up on high-quality masks, get vaccinated, upgrade the quality and quantity of air cleaners, re-stock on rapid tests, and encourage others to do the same.Two graphs, described in Tweet.
Oct 7, 2024 • 4 tweets • 2 min read
PMC COVID-19 Forecasting Model, Oct 7, 2024
🧵 1/4

540,000 daily infections during the "lull" between the 9th & 10th U.S. Covid waves.

🔹1.1% (1 in 88) actively infectious
🔹19 million anticipated infections the next month
🔹Higher transmission than half the pandemicGraph: 10 waves of the pandemic Tables/stats: Current Levels for Oct 7, 2024 % of the Population Infectious 1.1% (1 in 88) New Daily Infections 541,000 New Weekly Infections 3,787,000 Resulting Weekly Long COVID Cases 189,000 to 757,000 Monthly Forecast Average % of the Population Infectious 1.3% (1 in 74) Average New Daily Infections 643,433 New Infections During the Next Month 19,303,000 Resulting Monthly Long COVID Cases 965,000 to 3,861,000 Running Totals Infections Nationwide in 2024 220,311,000 Average Number of Infections Per Person All-Time, U.S. 3.44 How Does Risk Increase wi... PMC COVID-19 Forecasting Model, Oct 7, 2024
🧵 2/4

Year-over-year, we have seen the steepest drop in transmission all-time on the back end of a summer/fall wave.

Similar transmission the next month, a very high lull. Expect transmission to accelerate in mid-Nov.Two graphs Year-over-year transmission. A very high late-summer wave, the highest all-time during Aug/Sep, followed by the steepest decline on the back of a summer wave, all-time. Forecast. Note similar transmission over the next month, 40-60% of the summer wave's peak. Expect transmission to pick up considerably in mid-Nov in anticipation of a winter surge peaking around New Year's Eve
Sep 30, 2024 • 5 tweets • 6 min read
PMC COVID-19 Forecasting Model, Sep 30, 2024
🧵 1/5

COVID transmission remains extremely high, but we're entering a "lull" in the U.S. sooner than anticipated.

Among all summer/fall waves, the 22% 1-week drop in transmission is steepest all-time.

Details:

In Friday's data release, the CDC retroactively corrected the prior week's numbers downward 6% (for Sep 14). This is a big correction, bigger than average, but nothing nefarious. The most recent week's numbers show an additional 1-week decline in transmission of 22% (from Sep 14 to Sep 21) on top of that 6% correction (for Sep 14), so the transmission estimates have fallen quickly.

Looking back, we estimate that the 1-week drop of 22% is the largest decline on the back end of any summer/fall wave in the U.S.

*If* these numbers hold against future retroactive corrections, it means people have about 5 weeks of similar transmission from today through Nov 7.

Why might we have seen a record decline in post-peak transmission?

Several hypotheses:

1) Reporting Error: The 22% decline could be driven in part by errors in real-time reporting. These average is 5%, based on our analyses of Biobot wastewater data. We do not have long-term data on the accuracy of Verily/CDC real-time reports versus retrospectively corrected values. In the updated graphic, we have added 95% confidence intervals for the real-time values based on Biobot data, which show that 95% of real-time errors fall within 8.33%. Note that the dotted lines do not show 95% confidence intervals for the forecast, merely how the best estimates would change if a large error in the real-time reports of +/- 8.33%. It’s possible that next week the data will get corrected upward, and the forecast will more resemble the top dashed line. In the next Tweet, we show the forecast for our old (Biobot-based model); it’s still showing a slower decline, but they update their data about 5 days slower than the CDC, so it is unclear whether it’s a big real-time reporting error at the CDC or just that the CDC is ahead of the game.

2) Unprecedented School Transmission: This is the largest wave during the August back-to-school period. It’s possible transmission disproportionately affected school children and their families, and in being more targeted than typical transmission, the wave went down faster that what is normative thus far in the pandemic.

3) Laissez Faire Public Health: Public health guidance has weakened (e.g., 1-day isolation policy, not strongly pushing additional mitigation), which likely pushed the peak of the 9th wave higher, which could have led to a faster-than-usual resolution. The model accounts for these changing dynamics reasonably well, but with the school issue noted in hypothesis #2, it is possible the weakened public health guidance disproportionately hit a subset of the population, which altered the back side of the wave.

4) Missing Data: There are no widespread state-level instances of missing data, as is often the case. It is possible that specific areas did not report this week, and if there is a bias toward higher transmission in those places, the numbers will get retroactively corrected upward. This is one example of the issues that contribute to #1.

5) Politics: There is no evidence to suggest the CDC is modifying transmission data for political reasons. We put deep trust in the fundamental scientists doing the critical work translating wastewater into meaningful downloadable data. The inferences, agency graphs, and guidance can be influenced by politics, but the data are sound, given the limitations noted under #1.

Overall, if the data hold or anything reasonable within the ballpark, which is likely, this means a more prolonged and slightly lower lull than previously anticipated. Those putting off medical appointments and other risky activities may see this as a slightly broader window (today through Nov 7) to get things done. Note that even under the most optimistic forecasting scenarios, transmission remains very high in absolute terms, even if low in relative terms.Graph #3 from the PMC dashboard. Shows a steep decline in transmission based on the most recent CDC numbers. PMC COVID-19 Forecasting Model, Sep 30, 2024
🧵 2/5

Note that while the CDC data show an unprecedentedly steep decline, Biobot data suggest more gradual changes, along the lines we have been forecasting the past several weeks.

This graph shows a resurrected version of our discontinued model 1 (Biobot-only) forecast.

I would not be surprised if the CDC data get retroactively corrected upward a little bit (this is common, not nefarious), AND the Biobot data go down a bit faster (they lag the CDC data by about 5 extra days). There is regional variation between the data sets, which means that BOTH models could actually be accurate without corrections.

Nonetheless, anything in the ballpark of these two forecasts suggests a "lull" from about now through Nov 7. It's a very high lull, but people find these dates useful for risk-based planning.Biobot-based model suggests a much more gradual decline, with transmission still bottoming out in early November.
Sep 24, 2024 • 25 tweets • 4 min read
As an expert in psychological assessment who has testified in court on cognitive assessments I've conducted, people should interpret carefully the new eClinicalMedicine paper on Covid-related cognitive changes.

Quick 25-pt thread⚡️
🧵1/25 Main figure from the paper. It has a lot of information but actually communicates very little that is meaningful. They authors suggest changes in general cognitive skills (A) and curiously mix this with figures showing more viral load among people infected with virus (B). The top half of A is virtually uninterpretable. The bottom half is vastly overstated. I think people see the big findings in B and think a lot is going on cognitively, when it's just about virus. The field of clinical psychology has developed, implemented, and evaluated normed broadband tests of cognition for the past 119 years.

These are highly specialized instruments with carefully selected tests to cover the breadth of key areas of cognition.

2/25
Sep 23, 2024 • 8 tweets • 5 min read
PMC COVID-19 Forecasting Model, Sep 23, 2024
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The U.S. continues to see an estimated 1.1 million daily COVID infections with 2.2% of the population actively infectious as we descend from the peak of a 9th Covid wave.

Transmission will remain very high the rest of 2024.Main PMC figure showing Covid transmission over time. It shows 9 waves. The current wave peaked in August, and we're still seeing >1 million infections/day in the U.S. PMC COVID-19 Forecasting Model, Sep 23, 2024
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Looking at the year-over-year graph, note that we're in uncharted territory for this point in the fall. Expect a very high "lull" in early November before the winter surge sets in.

As we have noted previously, our current estimates are likely slight underestimates given elevated school-based transmission and the CDC data standardization process.

Kids: They are smaller, and make smaller "contributions" to wastewater. Basically, it takes more sick kids to produce the average amount of wastewater virus to equate to an average infection (mostly in adults). This issue evens out over time, but it means the model may underestimate during back-to-school periods.

CDC: They describe the details of their process for standardizing data over time. It's very strong, much better than what most localized wastewater orgs or WWS do. It's a bit Dunning-Kruger to question basic wastewater scientists in doing the most fundamental components of their jobs, and the data continue to correlate >.90 with other metrics like Biobot. In comparing with other data, I take their estimates as spot on, but could also see arguments that they may underestimate transmission by 0-5%. It's something we always keep an eye on. Trust, but verify.

Transmission is magnitudes higher than much of the public realizes, so we focus on the big-picture view rather than quibbling over such issues that tend to balance out over time.

I hear @jlerollblues is considering weighting a model based on estimates of the proportion of infections in children. That's actually tougher to estimate than it sounds at first glance. You should key an eye on his models too and the work he and others are doing with the WHN.Estimating a "lull" the 1st week of November, but at an alarming 850k daily infections in the U.S.
Sep 10, 2024 • 7 tweets • 4 min read
PMC COVID-19 Forecasting Model, Sept 9, 2024
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Nationally, we appear to have passed the peak of our late-summer wave, and it's not pretty.

At peak:
🔹>1.3 million daily infections
🔹2.8% (1 in 36) actively infectious
🔹Transmission higher than 90.5% of the pandemic

We are showing a peak around Aug 10, but as you look closely at the graph and in later Tweets, you'll see it was bimodal, with near-identical transmission on Aug 10 and Aug 24.

The CDC consistently corrects historical data, so in hindsight, we might expect the official peak date to flip to the 24th, or for the stats on the 10th to jump higher.

We had expected that Friday's data release might show this was the largest summer peak all-time (by the slimmest of margins), but the prior week's data were retroactively corrected downward by about 5%.

This is a common occurrence, which is why it's important to focus on the big-picture forecast (very bad transmission the remainder of 2024) as opposed to minute details.

Let's walk through the details in this Thread....Figure shows the 9 waves of the U.S. COVID-19 pandemic. We are in the 5th-largest wave, and the 2nd largest summer wave. The statistics in the Tweet summarize the peak of the current wave. PMC COVID-19 Forecasting Model, Sept 9, 2024
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The current year-over-year graph on Covid transmission is troubling. We just had the worst August of Covid transmission in the U.S.

We are likely to have our worst September, worst October, and potentially worst November of transmission.

We expect to bottom out around 850,000 daily infections in early November, before the winter surge picks up.

These new monthly records for Covid transmission are the consequence of #LaissezFairePublicHealth, especially the 1-day isolation policy, but more generally that public health officials are not describing transmission frankly and the need for multi-layered mitigation.Graph of year-over-year transmission. The current surge appears to have peaked, just under the daily peak of the 2022 summer wave, and is setting the stage for four months of monthly records in transmission, based on year-over-year monthly comparisons.