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With Omicron: Negative Efficacy Like Never Before
UKHSA Vaccine Efficacy Statistics: 2022, Week 1
Because of my reduced Christmas posting schedule, I missed the UKHSA Week 51 report, so I owe you, loyal readers, a few graphs.
First, let us cast our minds back to the Week 50 report. Here’s what case rates by vaccination status looked like then:
At the time, remember, we were preoccupied by the effect of booster doses in restoring positive efficacy for the 60+ crowd; meanwhile, younger age brackets were sliding ever deeper into negative territory. For context: Between 15 Nov. and 12 Dec., Omicron still accounted for no more than a minority of infections in the UK.
The week 51 numbers, where the four-week running average is shifted just one week later, look vastly different:
This must be a combination of pre-holiday testing and Omicron, which by 19 Dec. was surging towards 40% of all infections in Britain.
The latest data from the 2022 Week 1 report that dropped yesterday reveal an even more pronounced pattern, with negative efficacy returning to every age bracket over 18:
For what it’s worth, the UKHSA test negative-control investigation of vaccine effectiveness against symptomatic Omicron infection (where vaccination rates in PCR negatives are compared to vaccination rates in PCR positives) finds that vaccine effectiveness in the double-dosed does not fade below zero. Their latest analysis includes 169,888 Delta cases and 204,036 Omicron cases. Here’s two doses of AstraZeneca with either a BioNTech or a Moderna booster:
And two doses of BioNTech with a BioNTech or Moderna booster:
As the Health Security Agency loves to tell us, their numbers showing negative efficacy are unadjusted, and doubtless unreliable, because there’s no way of knowing the precise size of the unvaccinated population. Nevertheless, it seems clear by now that negative efficacy is real. It looks like the more you test regardless of symptoms, the more you find it. This would be why it emerges so strongly in pre-Christmas testing, when millions of perfectly healthy people got tested to know whether it was safe to see their elderly relatives. This would also be why the effect is missing from the UKHSA test negative-control numbers, which look only at people who sought out testing because of illness.
Now as is customary, the 60-day death numbers …
and the 60-day death rates:
UPDATE: See also T. Coddington (at I Numero) on the same report.