2021-12-08/09/10 General

I was out of town for a few days. I think this mostly catches up.


This press release from Pfizer says that three doses of Pfizer will give reasonable protection against infection with Omicron, but two doses isn’t enough. Two doses should still protect against severe disease.

This Twitter thread on a report from Public Health England is a very good look (but depressing) look at Omicron. It says:

  • A lot of people have ragged on the travel restrictions as being punitive and ineffective. They found that there are almost NO Omicron cases coming from travellers right now.
  • They give a PRELIMINARY estimate of the vaccine effectiveness for AZ+AZ against Omicron infection at ZERO %. For Pfizer+Pfizer, they estimate ~30%. With a Pfizer booster, they estimate ~70-75% effective against Omicron infection. (While it’s too early to tell, they expect that two doses will give pretty good protection against severe disease.)
  • There’s a 3x to 8x increase in the risk of reinfections from Omicron compared to non-Omicron.
  • Vaccines are between 20x and 40x more effective against COVID Classic as they are against Omicron.
  • You are 3.2x more likely to catch Omicron from an infected household member than you are to catch Delta from an infected household member.
  • The secondary attack rate for Omicron is 2x that for Delta.
  • Omicron is doubling roughly every three days.

This Twitter thread estimates that a fresh second dose of Moderna doses will be ~52% effective against Omicron infection and that a fresh second dose of Pfizer will be about 30% effective against Omicron infection.

This Twitter thread has a nice visualization of their vaccine effectiveness estimates:

This preprint from England (part of the data from Pub Health England referenced above, perhaps?) says that against Omicron infection:

  • AZ+AZ gives no protection.
  • AZ+AZ with Pfizer booster brings effectiveness up to 71%.
  • Pfizer+Pfizer starts at 88% effective, but drops to ~35% effective over time.
  • Pfizer+Pfizer with Pfizer booster brings effectiveness up to 75%.

The BC COVID-19 Working Group put out another video. One of the things they pointed out was that in the past, we’ve seen kind of a constant fraction of cases lead to hospitalizations. We don’t know what fraction of Omicron cases will lead to hospitalization, but no matter what the fraction is, if you have exponential case growth, hospitalizations will also grow exponentially.

This Twitter thread points out that we shouldn’t be saying, “Omicron is milder” as much as “immunity is kicking in”. We have very little data about what Omicron does to unvaccinated people.

This tweet points out that the faster the spread of a variant, the slower its hospitalization lag will seem to be. The dots on this graph are the crossover points where the fastest (simulated) variant “catches up” to the slower (simulated) variants:


There has been speculation (but not proof) that a nasal vaccine would give better protection against infection than intramuscular shots. Today, this preprint says that yes, nasal vaccines do in fact provide better protection (in mice). Yay! Bring on the nasal COVID-19 vaccines!


This preprint says that SARS-CoV-2 infects fat cells! This might explain why obesity is such a high risk factor for COVID-19. (This mass-media article is a very good discussion of SARS-CoV-2 in fat.)

This preprint says that having had a “common cold” coronavirus infection in the past does not help you when SARS-CoV-2 comes knocking, and in fact can hurt a little bit!

This article says that the case fatality rate in Canada has gone down from 6 percent at the start of the epidemic to down around 2 percent now.


This report from Pfizer to the US FDA says that a booster of Pfizer was 95% effective against (pre-Omicron) COVID-19 compared to only two doses of Pfizer.


This article reports that the US FDA approved Evusheld, which is a polyclonal antibody (tixagevimab and cilgavimab) for use sort of like a vaccine: the antibodies hang around in your immune system for six months and help prevent infection. It was 77% effective at preventing infection.

Unfortunately, that this preprint says that almost all of the monoclonal antibodies are worthless against Omicron. Regeneron, Evusheld, Eli Lilly’s bamlanivimab/etesevimab combo, none of them work. Sotrovimab from GSK and a Chinese monoclonal antibody (DXP-604) in development have reduced effectiveness but is still good enough.

Recommended Reading

This article is a nice lay overview of what we know about how well vaccines stack up against Omicron.

Mentioned above, this article talks about SARS-CoV-2 and fat cells.