Another poster here suggested that we are seeing the mRNA vaccines causing an immune response on a particular axis and that has caused selective pressure on mutations resulting in mutations such as Omicron, which in turn manifests more symptomatically in the vaccinated.
We have some correlation, but no exploration of causation. Id suggest that twitter thread is jumping to conclusions without considering the why.
If this variant is mostly asymptomatic, but spreads rapidly, in the vaccinated population, then you would also see higher rates in the vaccinated population, given that vaccinated people only test after they are notified that they have been in contact with someone who tested positive.
This gives a larger window for the virus to spread further among the vaccinated part of the population before containment.
If unvaccinated has to be tested to participate in social activities, they'll get tested more often and isolate if they get a positive test preventing spread to others in their group (this assumes that unvaccinated group together somewhat, which I don't have any evidence for besides anecdotally)
Being vaccinated might also lead to risky behaviour disproportionate to the risk mitigation provided by the vaccine - it might be a consequence of risk homeostasis, but the risk has now increased, which skews the bias towards more infections in the vaccinated group.
How big is omicron prevalence in Denmark? ECDC data appears to be way outdated. It can be possible that unvaccinated catch the Delta first for some reason. Perhaps because Delta is still more prevalent and does not affect vaccinated so easily but omicron does.
Behavioral changes may also explain some of the difference. If the testing has been mandatory for long time, I would expect some testing fatigue to appear resulting in lower social activity for unvaccinated.
Are there recent seroprevalence studies available? How many from the current unvaccinated population are still uninfected? Previous infection may offer still reasonably good protection against omicron regardless of lower laboratory neutralization activity.
Of course there is also possibility that vaccinated are more affected by omicron but I would then not expect the third dose to increase the protection against it but lower it instead. Efficiency should also increase in time, not get lower. Unless there is some mechanism involved that leaves previously vaccinated people with waned immune response even more vulnerable that people without any previous immunity.
About 90% of Omicron infections are in the vaccinated. They are about 75% of the population.
If Omicron spread equally among both vaxxed and unvaxxed, you should see percentages that represent their fraction of the population.
I don't believe this can be due to different behaviour or restrictions on unvaxxed because society is open if you have a negative test.
Very interesting. It's almost as if this experiment is having unforseen consequences XD