There might not be a post next week because I will be travelling (with a mask on!).
COVID-19
Long COVID
This paper from USA (2025-05-15) reports that 3.89% of people over 65 in a ginormous cohort (3.5 million!) had Long COVID. People who had four vaccine doses had a 39% lower adjusted rate of Long COVID than the unvaccinated.
🎉 This paper from USA (2025-06-02) reports that, after two years, children who had multisystem inflammatory syndrome in children (a very severe illness which can happen after COVID infection) improved significantly. Most of the kids had cognition, behaviour, and quality-of life scores that were comparable to siblings and/or community controls. Still having executive functioning issues at the two-year mark correlated with being admitted to ICU and to having a lower left ventricular ejection fraction when they had been hospitalized.
The conclusions of this preprint from California (2025-06-02) says “[post-acute sequelae (PAS)] outcomes occur with similar frequency among non-severe COVID-19 cases and influenza cases. However, PAS among COVID-19 cases are [24%] more likely to require hospital admission than PAS among influenza cases”, making it seem like “COVID is like the flu”. HOWEVER, the preprint kind of buries that:
- COVID-19 patients were 59% more likely to need hospitalization than the influenza patients;
- hospitalized COVID-19 patients were 49% more likely than hospitalized influenza patients to get a PAS diagnosis 91-180 days after their infection.
They also didn’t mention that people get COVID every 1.5 to 2 years, but only get the flu about once every ten years.
If you work the math, and figure how much more often people get COVID then flu (5x), how much more often they get hospitalized (1.59x), how much more often they get PAS if hospitalized (1.49x), and how much more often they have to be re-hospitalized for their PAS (1.24x), then the chance of requiring hospitalization for Long COVID is 14.7 times higher than for Long Flu.
COVID-19 is not just like the flu!!!!
This paper from Quebec (2025-06-01) reports that between 2.1% and 8.5% of adults who had a positive SARS-CoV-2 test had a new-onset psychiatric complication — which got worse over time. They also said that “COVID-related symptoms such as impaired sensory function and pain, and impaired body system function, and post-COVID cardiovascular, respiratory, neurological, and other complications predicted post-COVID psychiatric complaints.” Those symptoms sure sound a lot like Long COVID to me, so this paper basically seems to be saying that Long COVID sucks and makes people unhappy.
Treatments
💊 This paper (2025-05-12) reports that hamsters infected with COVID-19 infection and given probiotics (for 7 days before and seven days after the infection) did significantly better than infected hamsters which did not get the probiotics.
Apologies, the image isn’t very clear in the original paper.
The probiotics were either one of two strains of Bifidobacterium breve (I5979 or I5644) or LR (a mix of Bifidobacterium longum LA101, Lactobacillus helveticus LA102, Lactococcus lactis LA103, and Streptococcus thermophilus LA104).
Transmission
🦌 This paper from USA (2025-06-03) reports that the Alpha strain (among others) of COVID-19 was found in white-tailed deer in Ohio in 2023 — more than a year since Alpha was seen in humans in Ohio. A deer in Pennsylvania had a close variant, which gives even more evidence for deer-to-deer transmission. (I was already convinced: I couldn’t imagine enough human-to-deer transmission to account for how many deer were sick. It’s not like the deer were going to the same nightclubs as the humans.)
Pathology
🤰👶📆 This paper from USA (2025-05-31) reports that babies whose mothers had COVID-19 infections during the first trimester of pregnancy did poorer on a number of markers than babies whose mother had COVID-19 in the second or third trimester, or who didn’t have COVID-19 during pregnancy. The babies exposed in the first trimester had significantly smaller birth weight, length, head circumference, and were born earlier.
🩸 A restriction in blood supply to tissues can cause a form of programmed death in red blood cells, which then burst an spill their guts into the surrounding area. This paper (2025-06-04) reports that (if I understand correctly) the envelope of the red blood cells (RBCs) can help block holes in endothelial cells. However that if there is too much RBC death, then the husks of the dead RBCs can form microclots and block small blood vessels. This might be part of some cases of Long COVID.
Variants
I tried to document the lineage of NB.1.8.1 two weeks ago; this post (2025-05-27) does a much better job than I did:
Recommended Reading
💉 If you are a vax nerd, Hilda Bastian’s monthly vax roundup (2025-05-31) has a lot of news. There’s not really much that’s actionable for you at the moment, but I want to repeat that we will have much, much better COVID-19 vaccines in 2-10 years.
😷 This blog post (2025-06-05) is very good at reminding everybody why you should wear a mask:
- a third to half of all infections are asymptomatic and yes you can be (probably are) contagious even if asymptomatic;
- you can be contagious before your symptoms appear;
- rapid tests have a very high false negative rate (especially when you are pre-symptomatic or asymptomatic), meaning you don’t know when you are contagious and neither do the people whose air you are breathing;
- the symptoms are highly variable – cough, fatigue, diarrhea, etc. etc. etc. — and change based on the strain and the individual;
- getting vaccinated doesn’t protect you against infection for very long;
- COVID-19 can spread through the air for quite long distances. Six feet of distance isn’t going to protect you.
The post didn’t even talk about how bad COVID-19 infections are for you.
This five-year retrospective from Germany (2025-05) is long, but has a good, solid discussion of what was known when, why various measures were taken, and what the effect of the measures were. Its bottom line is basically, “Public Health in Germany really did follow the science, and the measures taken were reasonable and effective”.
H5N1
Transmission
There are quite a lot of papers which look at transmission of H5N1 between ferrets, either by direct contact or across an air gap. The researchers infect some ferrets, pair those ferrets with uninfected ferrets in the same cage or airgapped, wait about a week, and see how the initially uninfected ferrets did.
| Date/Paper | Strain | Direct contact infection | Airgapped infection |
| 2025-05-28 | A/Michigan/90/2024 | 100% | 50% |
| 2024-10-28 | A/Texas/37/2024 | 100% | 66% |
| 2024-06-22 | A/Chile/25945/2023 | 100% | N/A |
| 2024-06-13 | A/Chile/25945/2023 | 66% | 0% |
| 2024-06-07 | A/Texas/37/2024 | 100% | 33% |
| 2024-05-15 | A/mink/Spain/3691-8_22VIR10586-10/2022 | 75% | 37.5% |
The different variants also had varying lethality. In the most recent study (A/Michigan/90/2024), none of the ferrets died, even ones which were inoculated by researchers; in the 2025-06-13 study, all the ferrets which got sick died.
Something I thought was interesting was that two studies which looked at fomite transmission found 0% transmission. They put uninfected ferrets for a few days into cages which had previously housed infected ferrets but had not been cleaned, and none of them got infected.