2021-12-14 General


According to this Twitter thread, which reported on a press conference in South Africa, Omicron now accounts for 90% of the cases in South Africa. (Note: it might not be displacing Delta, there might still be just as many Delta cases as before — I don’t now — but a huge number of Omicron cases.)

This press release from South Africa’s largest insurer says:

  • Two doses of Pfizer only provide 70% protection against Omicron hospitalization and 33% against Omicron infection.
  • For people who had a prior COVID-19 infection with one of the other variants, the risk of reinfection is much higher from Omicron than from other variants.
  • The risk of hospitalization is 29% lower for Omicron than for COVID Classic. Note: they adjusted for vaccination status, but as far as I can tell, not for prior infection.
  • Children have a 20% higher risk of hospitalization from Omicron than they did from COVID Classic.

From this Twitter thread, the effectiveness of two doses of Pfizer against Omicron is highly age dependent:

  • 18-29: 92%
  • 30-39: 75%
  • 40-49: 82%
  • 50-59: 74%
  • 60-69: 67%
  • 70-79: 59%

Note that the first identified Omicron case was only five weeks ago, so it is still early. Take any Omicron-related information (in particular, anything that says it is “mild”) with a grain of salt. This article talks about why it might be milder in South Africa than elsewhere.

I am seeing lots of anecdotes of “holy shit, Omicron cases are exploding in <my location>!”

I feel like I am watching a train wreck or a tsunami. It’s coming everyone! Batten down your hatches! Please panic, at least a little bit.


This paper found the risks of myocarditis was lower after vaccination than after COVID-19 infection. They also didn’t find any vaccine-related cases in people under 40. Per one million vaccinations, they found

  • two extra cases after one dose of AZ,
  • one extra case after one dose of Pfizer,
  • six extra cases after one dose of Moderna and ten cases after two doses, and
  • forty extra cases after a positive COVID-19 test

This preprint, this preprint, this preprint, and this preprint all say variations on the theme of “holy cow, our vaccines are shit against Omicron, at least in test tubes, but boosters help a bit”:

  1. No neutralization efficiency for Pfizer, but a booster raises the neutralizing antibody levels by 100x.
  2. Pfizer has only limited neutralizing ability; a booster raises the neutralizing antibody levels, but it’s still only 25% as good as against COVID Classic.
  3. Neutralization was undetectable in most vaccinated people. People who got mRNA boosters were better, at about 17 to 25% as good as against COVID Classic. And wow, is Omicron infectious!
  4. There are almost no detectable neutralizing antibodies in people with two Pfizer doses, or in people who had been infected, and by the way none of the monoclonal antibodies except for sotrovimab and DZIF-10c work for shit either.

This Twitter thread explains paper #3 a bit. Here are some pretty pictures from that paper. WT is COVID Classic:

and here’s a pretty picture from paper #4. Wu01 is COVID Classic:

(Why are there so many papers coming out at the same time saying the same thing? Because it takes about two weeks to get results from this kind of neutralizing antibodies test, and everybody everybody everybody rushed to do these tests as soon as they could.)

(How can these tests show such shit response from antibodies, while the South African insurance company found 70% effectiveness against hospitalization? As science writer Katherine Wu says, “T cells, fuck yeah!” T-cells are your friends.)


The spread in South Africa is NOT slowing down. From this article:


Good news (finally)! This article says that paxlovid, Pfizer’s pill to prevent COVID-19 hospitalization, is still 89% effective. (Merck said their pill, molnupiravir, was 50% effective at preventing hospitalization, but when the dust settled, it was only 30% effective. It’s thus a relief that paxlovid’s effectiveness stayed where it was.)