@peridito
From the number of cases now surfacing it seems as though this new strain has been around for some time .
So ...wouldn't it be apparent if it caused severe symptoms ?
And ,I might be wrong ,but I understand that not all labs processing tests can assess samples for S gene drop out .So not all Omnicron cases have been/will be identified .
No.
You still need x number of cases / hospitalisations to know for sure to be able to compare Delta to Omicron.
We haven't got enough data yet to be able to assess that to a level where the margin of error is sufficiently low.
Example. Say we have a case fatality rate of 1 per 100, that means for every hundred cases, only 1 death. If you only have 100 cases to draw data from in comparasion to that existing cfr, you might have a sample which is just randomly unlucky or unrepresentative and have 4 deaths. That could make the case fatality rate look much worse than it actually is. Or you might have none. Which would make it look milder. Thats why you have larger sample sizes and you try to look for like for like populations so you can compare more fairly and eliminate the element of luck. Basically you have to have a sufficient margin of error to rule out the effects of luck and to try and spot patterns by demographic difference.
All we can do at this point is recheck previous samples for the drop S gene to see how many we might have missed, and then start to work forward on known cases and what outcomes are. Thats going to take a while. Especially if demand on labs due to changes to travel is increased at the same time.
What we have seen in this pandemic is that cases tend to start in one community within narrow age bands and then take a while to spread to different age groups and socio-economic groups. This can really distort things early on. So we have to adjust for things like housing density, underlying health, socio-economic status, genetic predisposition, life style etc etc. Until you do that, you are still in the land of anecdote rather than scientific analysis.
What happens in South Africa for an outbreak in a black poor area with very poor crowded housing with low life expectacy and low vaccine uptake coming into Summer is very difficult to compare and assess what will happen in an aging south asian population with high levels of things like diabetes but with relatively high vaccine uptake living in the North West of England in late November. They aren't directly comparable.