2026-03-13 General

COVID-19

Long COVID

A question that I get asked surprisingly frequently is, “but hasn’t Long COVID decreased a lot?” and I surprisingly didn’t have really good evidence either way to point to. Well, now I have something: this review paper (2026-03-10) reports that Long COVID prevalence was 35.5% in the pre-Omicron era and is 22.8% in this Omicron era. The Beta era had 59.5% prevalence; COVID-Classic only had 18.3%. So yeah, the Long COVID rate is down, but it’s still significant.

Fatigue was the most common symptom in all eras, but there were differences in other symptoms. Compared to Pre-Omicron, Omicron Long COVID patients have:

  • less shortness of breath;
  • less messed up smell/taste;
  • fewer sleep problems (although sleep problems tended to resolve over time);
  • more brain fog;
  • more tingling/numbness;
  • more palpitations;
  • more eye issues.

👂❓🐂💩 I have written before about how a stellate ganglion block — anesthetizing both halves of the vagus nerve (but not at the exact same time!) — has helped people with Long COVID, especially people who have smell/taste issues. Today I found multiple people claiming that ear massages stimulate the vagus nerve. I will admit that this made my bullshit detector wave a little bit but it seems like it would be harmless to try. I am not a doctor, but I can’t see how this could possibly hurt, so if you have Long COVID and nothing is helping, maybe try massaging your ears?

💊 This paper from USA and Mongolia (2026-03-12) reports that taking vitamin D3 didn’t reduce either the rate at which people caught COVID-19 from (already sick) household members, or how much healthcare they sought during acute COVID-19 cases. They did see a small decrease in Long COVID incidence (21% instead of 25% in the placebo group), but it was right at the boundary of statistical significance.

COVID-Related Excess Sickness and Death

🦀 Let’s talk about cancer.

I have seen scholars suggesting that COVID-19 might increase the risk of cancer (e.g. this paper (2023-05-23) and this paper (2024-05-03)). I’ve seen random people on teh socials assert that COVID-19 does increase the risk of cancer (frequently citing this report (2025-07-03) or this report (2026-01-13) which absolutely do not show that). I’ve seen articles citing anecdotal data (e.g. this article (2026-06-12)). But I have seen very few papers which show iron-clad cause and effect.

To be fair, it’s really hard to do because you don’t know if the patients got COVID-19 because they were weakened by undiagnosed cancer or not. It’s really hard to say that someone absolutely did not have cancer before they got COVID-19.

This new paper (2026-03-11) comes close. It reports that patients previously hospitalized with severe COVID-19 have an increased risk of lung cancer later and it shows that in mice, severe infections make lung cancer worse.

Because it seems a reasonable place to put it, here are some of the COVID-influences-cancer papers that I have seen:

  • This paper (2024-05-03) reports that the SARS-CoV-2 spike increases cancer cell viability;
  • This paper (2025-08-14) reports that COVID-19 infections make people much more likely to have an HPV-associated cancer, including cervical cancer, vaginal cancer, anal cancer, vulvar cancer, and oropharyngeal cancer.
  • This paper (2025-07-30) reports that COVID-19 “wakes up” dormant breast cancer cells.
  • This paper (2025-05-30) reports that people who went to the ICU with COVID-19 had a higher risk of being diagnosed with cancer in the next few months. They explicitly thought that cancer caused those patients to go to the ICU, not that COVID-19 caused cancer.
  • This paper (2025-07-01) reports that new cancer diagnoses in a region of southern Italy jumped in January 2020.

(I’m not sure if that is all of the COVID-19-causes-cancer papers I have seen or not, but I know there have not been a lot.)

NB: It is true that cancer in young people is rising, but that started happening before the pandemic (and most of the Internet randos who are yelling “COVID causes cancer!” are citing papers that don’t even have data past 2019).

💊 This article (2026-03-09) reports that new prescriptions for stimulants for adults in Ontario in June 2024 was 2.75 times what it was in Jan 2016. (The population growth over that period was only ~20%, so you can’t blame the increase in prescriptions on population growth.)

Variants

🧬 This snippet doesn’t give you actionable information, but I think it’s really interesting.

There’s a guy Mark Johnson in the US who follows what are called “cryptic lineages” — COVID-19 variants which show up in wastewater, which look nothing like what everybody else is sick with at the time, and which tends to persist for a very long time. There is widespread belief that these cryptic lineages come from individual people who are sick with COVID-19 for a very long time, possibly because they are immunocompromised. They can shed a LOT of virus, more than you would imagine. (This is part of why I am willing to believe that the sudden drop in the Annacis wastewater COVID-19 level at the beginning of October came from one person leaving the sewershed.)

Johnson has found another cryptic lineage in Lincoln, Nebraska. It descends from B.1, which disappeared from everyone else in 2021. The cryptic strain is incredibly different from other strains, as shown in this graph of how closely different strains are related:

Map of how closely related different strains are to each other. The distance between two strains on the map corresponds to how genetically different the two strains are.

This strain descends from B.1 but has 385 mutations since then.

Transmission

🦇❓🧪 Something people ask me a fair amount is whether I think COVID-19 originated in a wild animal (zoonotic spillover) or in a lab.

I fundamentally don’t care. It matters a whole lot to me what we humans do with this virus that we now have to deal with, but it doesn’t matter much to me where it came from. If a thief breaks into my house and steals my television, I don’t care what the thief’s home town is, what I care about is how to stop the thief from stealing from me again.

But because I know a lot of people for some reason care, I will tell you about this paper (2026-03-06) which looked at mutation patterns in five types of viruses before they jumped to humans. Apparently they can tell what kinds of mutations viruses have when they live in non-humans, what kinds of mutations they have when they live in test tubes, and what kinds of mutations they have when they live in humans.

For all but one of the viruses, they found that the types of mutations that they gained before they jumped to humans, they had animal-ish mutation patterns. Exactly one had test tube-ish mutation patterns, but it wasn’t COVID-19: it was an influenza virus that showed up in 1977. The “Russian flu” of 1977 showed up first in the Soviet Union, and looked more like a human flu from 1950 than any of the circulating animal influenzas. What differences the 1977 strain did have from the 1950 strain looked very much like mutations viruses get when they a grown in cells. They think that one probably escaped via a lab accident.

COVID-19, they said, looked genetically like a bog-standard zoonotic spillover.

Pathology

🏃‍➡️ This paper from Norway (2026-03-10) reports that people who exercised more didn’t have any lower risk of catching COVID-19 than people who exercised less. However, they found that the more people exercised more before they caught COVID-19, the less likely they were less likely to be hospitalized.

Caution though: maybe frailer people exercise less.

I have seen a few articles about this paper from South Korea (2026-03-09) with headlines along the lines of “coming to work sick makes you more likely to get sick again later!” That’s not quite what the paper says.

The paper does say that people who came to work while sick were 30% more likely to get sick in the next wave than people who were not sick. However, they said that people who stayed home when sick were almost 3.5 times more likely to get sick in the next wave than people who were not sick in the current wave. (NB: They never said what kind of wave, but the survey timeframe was 2019 to 2022, so I am guessing it was COVID-19 waves.)

So really, what this paper says is that people who get sick in one wave are more likely to also get sick in the next wave.

Influenza

Vaccines

💉 This report from USA (2026-03-12) reports that the influenza vaccine was not as effective this year, mostly because subclade K (which was dominant this year) showed up after they had started making the flu shots.

AgeAgainstFlu TypeVE
<18outpatientboth38-41%
<18hospitalizationboth41%
adultsoutpatientboth22-34%
adultshospitalizationboth30%
<18outpatientflu A37%
<18hospitalizationflu A42%
adultsoutpatientflu A34%
adultshospitalizationflu A30%
Some numbers are ranges because the study took data from three different sources.

For reference, this report (2025-02-27) from last year says that the previous year’s vaccine effectiveness was between 32-60% against pediatric outpatient visits and 63-73% against hospitalization. For adults, the previous year’s vaccine VE was 36-54% against outpatient visits and 41% to 55% against hospitalization.

Dengue

Vaccines

Note: I, uh, oops, didn’t realize or had forgotten that Butantan wasn’t the first dengue vaccine. I edited on 2026-03-14 to discuss previous vaccines and expand a little on why dengue vaccines are hard to make.

🎉🎉🎉💉 I realize that Canada has very few dengue cases, but dengue is a big problem in many places in the world, including some places that you might want to visit. This paper (2026-03-04) reports that a new vaccine, Butantan, has 65% effectiveness against PCR-confirmed symptomatic dengue infection and 80.5% effectiveness against hospitalization for at least five years.

This is a BFD. It’s not the first dengue vaccine, but it looks good. Dengue was really, really hard to make a vaccine for: there are four different strains (DENV1-4), and if you got&recovered from a one strain, it would make infection with a second strain worse because of antibody-dependent enhancement.

  • The first dengue vaccine, Dengvaxia (see Wikipedia), had real problems with antibody-dependent enhancement, and this article (2024-10-23) says that the manufacturer is going to stop making it some time this year.
  • This paper with data from eight countries (2022-07-01) reports that the vaccine effectiveness of Dengvaxia was similar to Butantan’s, but its effectiveness was uneven: it was great against DENV1 and DENV2 but not so good against DENV3 and miserably against DENV4. This paper (2024-01-31) did mathematical modeling which says that while Qdenga has really good effectiveness against DENV2. Vaccine effectiveness usually wanes over time, and Qdenga is no different — but its effectiveness against DENV1 and especially DENV3 and DENV4 actually go negative after one to three years.
  • Butantan was tested in Brazil, and they didn’t see any DENV3 and DENV4 cases, so we don’t know what the vaccine effectiveness is against DENV3 and DENV4. Maybe that’s okay for Brazil: from the Dengvaxia paper, it looks like Latin America doesn’t have much (any?) DENV3 and DENV4. (DENV3 and DENV4 did show up in their subjects from the Philippines, Sri Lanka, and Thailand.)

Polio

Transmission

This article (2026-03-10) reports that Canada has issued a travel advisory for Germany and the UK because of polio. This was a WTF moment for me because I had not seen anything about elevated risks of polio there.

I did a little digging. I found that four months ago, and again in January, the authorities in Hamburg Germany spotted polio in the wastewater, but there were zero cases identified. There were no further wastewater detections that I could find articles about.

For the UK, it looks like they found two wastewater samples, one in Jan 2025 and one in Sept 2025, with zero cases identified.

I don’t know what’s going on that isn’t getting reported in the news, but just based on the news, it does not seem like Germany and UK are having massive scary outbreaks.

If you aren’t sure if you got a polio shot, and want to go to Germany or UK, sure, get a shot. As long as there is polio somewhere in the world, it’s certainly possible that you could catch polio. However, it is not obvious to me why you’d be in any more danger in Germany or UK than you are here in BC.

Measles

Transmission

I said above that in my personal opinion, you probably aren’t at much risk from polio if you go to Germany or the UK. In my non-doctor opinion, you are probably in much more danger if you travel to Florida — from measles. This article (2026-03-13) reports that Florida isn’t doing comprehensive infection control procedures, which — coupled with their low vaccination rate — makes it sound like they are likely to have huge uncontrolled spread soon.

According to the Government of Canada Measles and Rubella Monitoring Report (updated 2026-03-09), in the week ending 28 February 2025, the following jurisdictions had the following number of measles cases:

  • Canada: 74;
  • Manitoba: 41;
  • Alberta: 31;
  • Ontario: 1;
  • BC: 1.

Recommended Reading

I remember seeing an exchange on teh socials maybe ten years ago, where an anti-vaxxer was saying something along the lines of, “Well, what did they do about measles before vaccination, eh?” and the response was “THEY DIED.”

Measles is not an easy disease. If you wonder why we’re making such a big deal about it, please read this article (2026-03-13) or this article (2026-03-13).

It’s also expensive and labour-intensive to contain outbreaks, as this article (2026-03-11) reports.

Measles is a big, big, big deal, I wish more people understood that.