2022-03-31 and 2022-04-01 General

Mitigation Measures

This article reports that, as advertised, the Government of Canada has dropped its requirement for a COVID test to enter the country for fully vaccinated travelers. Note that you do still need to fill out the ArriveCan app’s survey before you cross.


Wow, this paper says that pregnancy increases your risk of a COVID-19 breakthrough infection by 91%, more than various things that immunocompromise you, more than mental illness, WAY more than cardiovascular issues:


This paper, like two other recent papers, said that your risk of developing diabetes if you get infected with COVID-19 goes up significantly. Interestingly, it says that the risk is higher if you are male but not if you are female! (Yes, I know it looks like the risk to woman is still >1, but the confidence intervals are such that you can’t definitely say that the risk is higher than 1. I simplify for you. If you want to see the actual confidence intervals, go read the paper.)

male riskfemale risk
120 days after infection2.56x1.21x
120 days to up to 14 months1.95x1.04x

For patients who had been hospitalized, oddly the risk was not as high. The risk of getting diabetes was actually lower in infected women than controls!

male riskfemale risk
120 days after infection1.42x0.72x
120 days to up to 14 months1.32x0.80x

(The study looked at people who had been infected between 1 March 2020 and 1 March 2021, and they followed up through June 2021, so the maximum follow time would be less than 14 months.)


This preprint found that giving people who were low in Vitamin D didn’t help with COVID-19 or acute respiratory events. Too bad, I really wanted Vitamin D to be helpful (because it is so cheap and easy).


This article says that 3.2M doses of Novavax have arrived in Canada!

This paper from Sweden says that a COVID infection is like a vaccine which is 95% effective against infection and 87% effective against hospitalization (in the alpha to delta variant timeframe). Vaccination plus infection is even better. Compared to infection-acquired immunity against infection:

  • One dose was 58% effective;
  • two doses were 66% effective.

(Those might look low because you’re used to seeing effectiveness’ controls being naive (unvaccinated, uninfected), while these numbers are compared to people with infection-acquired immunity. Also note that the effectiveness of infection-acquired immunity in this study is for alpha and delta; it’s was lower for Omicron.)

This paper from Sweden found that infection acquired immunity plus vaccine had the following effectiveness against symptomatic infection compared to controls who did not have a record of having had COVID-19 but who did have at least one negative PCR test:

Brand1-dose VE2-dose VE

I was surprised at how poor the J&J vaccine was compared to the others. I had the impression that the J&J was actually a reasonable vax, and that the other vaxes looked better just because they had two doses. Maybe not?

This paper said that of people who got myocarditis after vaccination, 93.9% were male, 87.1% got it after the second dose, and 93.2% recovered.

Meanwhile, this report says that the risk for cardiac outcomes was 1.8–5.6 times as high after SARS-CoV-2 infection than after the second vaccine dose


This report from the UK says that you are almost twice as likely to get reinfected with Omicron as you were with any of the different strains.

This paper said that there were 6-8x as many Omicron cases per capita in kids as Delta cases, and that most cases were in kids under 2 years old. Fortunately, Omicron was less severe.

This preprint found that antibodies for BA.1 didn’t do a particularly good job against BA.2 or BA.3, and really sucked against COVID Classic.

Recommended Reading

Confused about fourth doses? This blog posting summarizes what we know and don’t know in pretty exhaustive detail.