In one week #Omicron went from 13% to 73% of cases in the US. This is transmitting very fast, and transmission matters covid.cdc.gov/covid-data-tra…
This at a point when cases have been rising and this is already the reality in the North East - fueled by Delta nytimes.com/live/2021/12/2…
I am less sure now whether Omicron will completely replace Delta, or just be the more common cause of infection. After all, if cross protection is limited, that should matter
If omicron and delta coexist, this will make it important to tell them apart, quickly. because some monoclonal therapies effective against delta are expected to struggle against omicron.
for now, here it is again. Wow
• • •
Missing some Tweet in this thread? You can try to
force a refresh
Right now delta, which lest we forget is an extremely transmissible variant with substantial ability to cause breakthrough infections, is losing out to omicron in the US. The details are debatable, the overall trajectory is clear (from covid.cdc.gov/covid-data-tra…) 1/n
This is remarkable, but is it due to omicron dodging antibodies better than delta, or just being more transmissible, or both? We can gain some insights from this thread (by @maryebushman in my lab)
This is a crucial plot. It shows the combinations of the two key parameters consistent with what was observed in Gauteng. Not that 'population immunity' is not seropositivity, it is a representation of total immunity arising from both infection and vaccination 3/n
I am not ‘afraid’ of the virus. I am vaccinated and boosted and young (ish). I am concerned about what unmitigated transmission does to our society, and the potential of Omicron to cause outbreaks in places we don't want them 1/n
Imagine an outbreak among the team about to deliver your baby, some of whom suddenly have to isolate 2/n
Imagine an outbreak among the people who deliver your chemotherapy 3/n
To what does Omicron owe its remarkable properties? Immune evasion or inherent transmissibility. My bet is a bit of each. One thing though is beyond question - it is much better than delta at spread. Look at the household attack rate. This has implications 1/n
So Omicron is infecting roughly 2-3 times as many people as Delta, specifically in the setting of household transmission. It is not as clear outside households but remember, it is much harder to identify all potential contacts outside households 2/n
Lots of chatter about how early data show #Omicron is "less dangerous". But it is important to correct for the lag between infection and hospitalization when comparing the severity of variants with very different properties when it comes to transmission, here’s why 1/n
Imagine two viruses exactly the same in terms of severity, but one of them infects on average 3 people, and the other 1.1 (I know you can’t have 0.1 of a person, it’s an average). These are the effective reproductive numbers or Re and they determine how quickly they spread 2/n
If we start with 1000 infections with the less transmissible variant and just one of the more, we would expect the latter to overtake the former by the 7th generation (assuming nothing changes). Exponentials are wild 3/n
#Omicron data continue to accumulate, with this being perhaps the most serious indication I have yet seen about what we should expect in the next few months. Like @theosanderson says, these are increases in *daily* results 1/n
Was distracted before continuing the thread, and in that time this dropped. Once again the @UKHSA has provided incredibly prompt data collection and analysis. The upshot is that #omicron is definitely transmitting very readily indeed, and that matters 2/n assets.publishing.service.gov.uk/government/upl…
Even if Omicron infections are mild (and they might be, especially in vaccinated people) they would have to be really really mild to prevent an acute burden on healthcare that is already stretched, resulting from very large numbers in a short period of time that will add up 3/n
There is a lot of anger in the UK about this. More to the point it is an unambiguous and appalling failure to take the pandemic seriously at one of its most damaging inflexion points. It has come to light at another such moment as Omicron surges 1/n itv.com/news/2021-12-0…
Look at the date of the video: 12/22. In other words the week *after* Matt Hancock announced the existence of B.1.1.7/Alpha in the House of Commons and warned how serious it was. The partygoers cannot pretend to have been unaware 2/n newscientist.com/article/226307…
And look at the consequences of such behavior, the spike in Alpha transmission that was the result 3/n