Thread by @EricTopol

Does Omicron lead to less severe illness than prior variants ? We don't yet but let's review what is the basis for the hope /1
nytimes.com/2021/12/06/wor…

In South Africa, among those hospitalized, less requirement for ICU for those admitted compared with Delta /2
ft.com/content/d315be…

And the same, much less ICU need among those testing positive /3

Can this be generalized given the younger population in South Africa, with very extensive prior Covid, and many of the cases among vaccinees? That's an uncertainty that will remain until we see much larger numbers of people age 60+ without immunity /4

Meanwhile there is clear evidence of very rapid growth of Omicron in South Africa and similarly in the UK, displacing Delta /5

https://twitter.com/chrischirp/status/1467944178713862146

https://twitter.com/AlastairGrant4/status/1468151959957950466

The extent to which this enhanced spread is due to Omicron's immune evasion or more contagiousness (or both) is yet unclear. But the net result is more people in the hospital, as seen in Omicron's epicenter /6

Not much has been said of Omicron's potential to induce #LongCovid, but with such high transmission levels that is certainly a concern, as even mild cases can be associated with prolonged disability /7

Perhaps the safest thing to conclude at this point is that there's no signal for Omicron causing more severe disease than Delta. The case for milder should be viewed as tentative, admixed with hope, amidst many other worrisome signs /8

To sum things up, this is likely the best explanation for what we've seen to date
"The potential for Omicron to result in less severe symptoms may be more a consequence of immunity than the virus evolving to become less virulent."--@rjlessells @FT #2 in🧵