2022-02-02 General

Happy Twosday!


This article reports on the results of the first human challenge trial (meaning: deliberate infection) of COVID Classic. You’re going WAIT WHAT? HOW COULD THAT POSSIBLY PASS ETHICS REVIEW? This happened in the UK (so different ethics boards), and they did work hard to minimize potential harm to the subjects (like making sure subjects were young and ultra-healthy, having Regeneron on hand, monitoring hard), and it was scientifically very valuable. For those reasons, the ethics board approved it. (Me, I would not have approved, but they didn’t ask me.)

I read the preprint carefully and found a number of things:

  • About half the volunteers (18 out of 34) got sick with a very small dose. (It was ten times lower than what the World Health Organization had estimated would be needed, and 1K-10K less than what has been used in primate studies!)
  • Detectable virus showed up first in the throat, then the nose.
  • Peak levels were much higher in the nose than the throat. (Cover your nose with your mask!!)
  • Virus was detectable very fast – on an average of ~1.7 days after infection.
  • Peak symptoms occurred 4-5 days after infection.
  • The PCR tests continued to detect virus 14 days post-infection, but they could only culture virus for about 10 days on average. (Culturing virus is the absolute gold standard. PCR tests can report positive in the presence of dead virus pieces.)
  • Lateral flow tests worked well at recognizing the virus eventually, but they generally didn’t start registering until ~4 days post-infection. Lateral flow tests kept registering for about 1-2 days after they stopped being able to culture virus.
  • About 90% of the infected developed symptoms, mostly of the “common cold” type.
  • Symptoms didn’t correlate with viral load.
  • Two-thirds of the volunteers had some loss of smell, with half having complete loss. 61% still had some smell loss at 28 days. One person (of 18) still had measurable smell impairment at 180 days, though it was still improving.
  • Loss of smell happened later than the “common cold”-esque symptoms.
  • All of the infectees recovered without intervention (i.e. nobody got drugs or monoclonal antibodies) except for two people who got steroids for loss of smell and six who got some smell training.

This study looked at what factors influenced the wildly different case rates and fatality rates in different countries. In their analysis, case rates were influenced by:

  • interpersonal trust (accounting for 16.5% of the difference);
  • trust in government (7.4%);
  • population living below 100m (5.4%);
  • GDP per capita (4ยท2%);
  • seasonality (2.1%);
  • previous exposure to betacoronavirus (2.1%).

They found that fatality rates were influenced by:

  • population age structure (46.7%);
  • GDP per capita (3.1%);
  • population density (1.7%);
  • cancer prevalence (1.6%);
  • body mass index (1.1%);
  • smoking prevalence (0.3%);
  • air pollution (0.3%);
  • chronic obstructive pulmonary disease prevalence (0.2%)


This preprint says that

  • vaccination plus Omicron infection or
  • infection with a previous variant plus Omicron infection

gives you good protection against all of the previous variants. However, Omicron infection by itself does only rarely give good protection against other variants.


This study of healthcare workers taking rapid antigen tests during the Omicron era found that:

  • 40% of the HCW still tested positive on Day 6 after symptoms.
  • People who had been boosted were 3x more likely to test positive on Day 5, and ~2x more likely to test positive on Day 6 than unboosted people.

The authors say that letting people go back to work five days after symptom onset was reasonable for the disease progression pre-Omicron, but does not make sense for Omicron.

This article looks at why BA.1 spread widely before BA.2 showed up, despite BA.2 being more transmissible than BA.1.

This article talks about nasal vaccines.

This article talks about ways to improve fit of masks.

This article talks about people (in the USA) going back to the dentist after a long time away.