Covid is: Airborne, Not Over, and Endemic

Unless people are immune for a while after getting covid/flu, so fewer people get it?

I guess what I mean is, why does each individual wave peak? At the peak of the wave the flu or covid is most prevalent, and many people have been infected so are more susceptible, so it should keep going up, right?

It's worse than vaccination alone at preventing infections? If I get infected once, I am more likely to get infected again than if I hadn't? How do covid waves ever stop?

I asked because I put in a reasonable scenario that I have once a week, and I got this for estimated risk: 4.29 expected infections per year. That seems unrealistically high? I wouldn't think that's possible with 2025 levels of immunity?

How are immunity from vaccination and prior infection taken into account in the model? I couldn't find any way to adjust them.

Not sure your covid & cancer stats are right.
From CDC Wonder for 2025:
wonder.cdc.gov/controller/s...

Not sure your covid & cancer stats are right.
From CDC Wonder for 2025:
wonder.cdc.gov/controller/s...

I know the "s" is for sarcasm, but just in case someone takes the immunity-debt thing seriously:

Influenza A/H1N1 and Influenza B are at very low levels this year (immunity working great), and only A/H3N2 is high, due to a new variant (Subclade K).

www.publichealthontario.ca/en/Data-and-...

Australia Admits All Those Animals Made Up

Australia Admits All Those Animals Made Up theonion.com/austral...

Fun ety/epi fact: The "dem" in "pandemic" comes from Greek "demos" meaning "people".
Fortunately we have another good word "panzootic" to mean the equivalent in animals, as in "H5N1 is panzootic in birds". Indeed it is!

I often get comments like "how can you say Covid is low when there's no testing"... there is testing in hospitals & testing protocols haven't changed really since Apr 2023, so covid admissions are comparable over last yr.

Plus Scottish wasterwater consistent with lowest Covid winter so far. 1/2

%ED visits for Covid is starting to decline in the first week of Jan.

Only 4 states had (slightly) higher %ED peaks in their December waves than their summer peaks:
🔸️Michigan
🔸️Maine
🔸️New Hampshire
🔸️South Dakota

Most were significantly below. Florida was 90% lower than Aug.

Polymerase mutations underlie adaptation of H5N1 influenza virus to dairy cattle and other mammals. In early 2024, an unprecedented outbreak of H5N1 high pathogenicity avian influenza was detected in dairy cattle in the USA. The epidemic remains uncontrolled, with spillbacks into poultry, wild birds...

Really proud to share our preprint describing early adaptation of H5N1 to US dairy cattle, and showing how these mutations enhance the ability of the virus to infect other mammals, such as pigs and humans.

With @influenzal.bsky.social @vidhid.bsky.social @drclairesmith.bsky.social and many more!

Are the "kids need to get infected with pathogens" folks in the room with you now?

This article from April 2022 discusses "Patients who develop ARDS typically end up on high flow oxygen, many need mechanical ventilator support, and many need extracorporeal membrane oxygenator (ECMO) support."

Thankfully that's extremely rare nowadays.

WHO DON: Trends of Acute Respiratory Infection, Including Human Metapneumovirus, in the Northern Hemisphere #18,534 For the past week or so the internet, and even the mainstream media, has been speculating over a rumored outbreak of a `mystery vi...

AFD Blog `WHO DON: Trends of Acute Respiratory Infection, Including Human Metapneumovirus, in the Northern Hemisphere' afludiary.blogspot.com/2025/01/who-...

Huh, the headline has been changed to make more sense.

HMPV is endemic in Australia and the rest of the world. You probably didn't even notice the last wave of HMPV in Australia, which peaked in October.

Is the NHS facing a 'quad-demic' this winter? No, but it is finding it harder and harder to cope with 'normal' winter pressures. Plus flu might still have a nasty kicker in store this winter.

Headlines are warning of a 'quad-demic' about the hit the NHS, but data show that a 'quad-demic' is v unlikely.

The worry is not that the NHS is about to be hit by unprecedented demand, but that it is unable to cope with normal demand.

I've written about it here
open.substack.com/pub/christin...

"The issue is not that the NHS is facing an unprecedented winter avalanche of illness - the issue is that the NHS cannot cope with an entirely precedented winter season." Very good substack from @chrischirp.bsky.social

Is the NHS facing a 'quad-demic' this winter? No, but it is finding it harder and harder to cope with 'normal' winter pressures. Plus flu might still have a nasty kicker in store this winter.

Fantastic piece from @chrischirp.bsky.social outlining the real issues the NHS is facing- challenging the quadremic idea and suggesting pragmatic ways we can PROACTIVELY reduce the impacts and spread of these diseases and help the NHS! open.substack.com/pub/christin...

Why would you want covid to be like flu? Flu peaks two and a half times higher than covid. If covid did that, hospitals would be swamped. Lucky it is more like rhinoviruses (less seasonal).

I think I would trust the ED surveillance as a quantitative measure.

The WW data shows a jump up at the same time, which corroborates the ED surveillance jump, but I wouldn't take the WW data as quantitative.

You're probably already aware, but the CDC has a really wonky way of calculating the "wastewater viral activity level". I don't think there's any guarantee it would be even close to proportional to infections, especially at the ends of the range.

www.cdc.gov/nwss/about-d...

I am really curious as to what sort of mathematical model you're using! Would love to understand how the peak could decrease by 40% but still occur on the same day. Seems odd. Is this based on a multi-variant SIRS model? If you've described it elsewhere, would appreciate a pointer to it. Cheers!

Venn diagram of four intersecting circles of different colours. Top left, yellow: "pandemic". Top right, green: "airborne". Bottom left, purple: "endemic". Bottom right, red: "dangerous". In the middle, in the intersection of all four circles: "COVID".

You are here:

It's interesting to look at the detection data for Whooping cough (also called Pertussis, named after the bacterial cause - 𝘉𝘰𝘳𝘥𝘦𝘵𝘦𝘭𝘭𝘢 𝘱𝘦𝘳𝘵𝘶𝘴𝘴𝘪𝘴.
Australian NNDSS data show a 3-5 year space between Pertussis epidemics.

But surely correlation, not causation? 😉

Just to be clear, my central expectation is just one winter wave, peaking well after 1 January.

(But I wouldn't use the word "forecast" for any of this kind of spit-balling!)

❄️ Holiday Season Forecast:

🔹The wildest forecast I've ever made was for Dec 2021, predicting multiple millions of daily infections. This one is easily second place. A very muted holiday wave relative to all prior years, due to weak evolution and large summer numbers.

I appreciate the broad prediction interval!

I find it interesting you (and many others, including those who claim "covid isn't seasonal") are still pegging the peak to 1 January.

(Personally, I think there *is* a fair amount of seasonal forcing, but I also expect a delayed peak this year.)