Wouldn't the fact that it's outcompeting Delta imply that there is some cross immunity?
I suppose there's some limited displacement effect e.g. if you have Omicron and self isolate you can't catch Delta during your self isolation period?
I suppose there's some limited displacement effect e.g. if you have Omicron and self isolate you can't catch Delta during your self isolation period?
Not really. If Delta's Rt is greatly reduced because lots of people have immunity, Omicron can show up with a much higher Rt and grow in case numbers. It doesn't need to further reduce Delta's Rt to "win".
I.e. even if R0 among those naive to the variants is similar, once you have 2/3rds of people who can't get Delta because of vaccination or prior infection and that can get Omicron, ... Omicron is going to win. And it looks like Omicron may be more contagious than Delta at baseline, so it's even quicker.
Otherwise, we could say something like "COVID outcompetes the flu".
I don't think we have the data on Omicron vs Delta yet as you say.
I mean, it does, but ... we don't really know that Omicron is outcompeting Delta in that sense. We know that Omicron case counts are growing, relative to Delta, but we don't know how well Omicron prevents later infection by Delta, etc.
You asked "Wouldn't the fact that it's outcompeting Delta imply that there is some cross immunity?" The only fact that we have right now is that Omicron is growing quicker than Delta, not that Omicron is somehow suppressing Delta with cross-immunity.
> Otherwise, we could say something like "COVID outcompetes the flu".
Well--- COVID causing everyone to be careful, combined with influenza's lower Rt due to not being novel, really put a dent in influenza. So even then, without cross-immunity, you can have growth in one suppress growth in the other.
If you are infected with omicron and are isolated, can you be infected by Delta from say...a shoe that picked it up days ago?
Answer: No, but that doesn't mean either disappear in the short term.