Thread by @DearPandemic

1/ Q: Is it true that #Omicron is less severe than previous variants?

A: We HOPE so, but we don’t know yet. The evidence so far is mixed.

dearpandemic.org/is-omicron-les…

2/ We are WAY past due for some good variant news. But pinning our #Omicron hopes on a less virulent variant is not wise for 2 reasons:

1) It might not be less severe in those who are “immune naïve” (neither vaccinated nor with a previous infection—still millions of people).

3/ 2) Many more infections *even* if less severe can still lead to an avalanche of hospitalizations and deaths, and the risk of long Covid.

@AdamJKucharski raised this last December w/ the rise of Alpha:

https://twitter.com/AdamJKucharski/status/1343567425107881986?s=20

4/ The rumors about Omicron were flying fast and furious even before it was granted its Marvel-character-sounding Greek letter.

“It spreads faster.” “The vaccines don’t work for it.” “It’s less virulent.”

Data is finally starting to come in to put these rumors to the test.

5/ Transmissibility:

Omicron is spreading faster than Delta, meaning it has a “growth advantage.” We don’t know yet how much is due to Omicron being inherently more transmissible v. better at infecting people w/ prior immunity (probably a bit of both).

https://twitter.com/BillHanage/status/1473133330942119946?s=20

6/ Vaccine efficacy

So far numerous lab-based neutralization studies + some real-world data suggest Omicron is better at evading antibodies generated from 2 doses of vaccines or previous infection, but 3 doses hold up well. Get boosted!

theguardian.com/world/2021/dec…

#Moderna

7/ Vaccine efficacy continued: @kallmemeg :

https://twitter.com/kallmemeg/status/1469351833416122369?s=20

8/ Virulence:

A mixed bag so far. Early data from South Africa was largely anecdotal—Doctors reported seeing Omicron cases as mild. As more data have come in, hospitalizations in South Africa still look lower for Omicron compared to previous waves.

https://twitter.com/jburnmurdoch/status/1471490003804954644?s=20

9/ Even if this holds up, decreased severity in South Africa could be a result of higher levels of population immunity (from natural infection + vaccination) compared to previous waves rather than any intrinsic characteristic of Omicron.

npr.org/sections/goats…?

10/ South Africa has already been hit *extremely* hard by previous waves of COVID-19, with excess mortality estimated at 230,000 deaths out of a population of 59 million, meaning much worse per capita than even poor performers like the U.S, U.K. and Brazil.

11/ If Omicron infects more people who have some level of previous immunity, it will look less severe overall even if the severity hasn’t changed for people who are “immune naïve,” as nicely illustrated by @roby_bhatt & @BillHanage

https://twitter.com/roby_bhatt/status/1471212023576870912?s=20

12/ South Africa is also a much younger country compared to Europe or North America. This all means that we can’t generalize too much from the experience of one country, as the impact on countries with different infection+ vaccination+ age patterns could be different.
#poptwitter

13/ 2 recent studies in lab culture showed Omicron may be less efficient at replicating in lung tissue compared to the upper respiratory track. Many scientists were quick to urge caution interpreting implications:

https://twitter.com/ArisKatzourakis/status/1472169946813804547?s=20

14/ 1st study: med.hku.hk/en/news/press/…

15/ 2nd study:

https://twitter.com/GuptaR_lab/status/1471941645797146628

16/ Recent data from the UK shows “no signal” of lesser severity for Omicron. This is concerning but still based on small numbers given the lag time needed to identify hospitalizations and the newness of the variant.

https://twitter.com/kallmemeg/status/1471869169037676553?s=20

17/ Hospitalizations in London, which has seen the earliest Omicron spike, are up sharply, perhaps a forecast of what is to come.

https://twitter.com/VictimOfMaths/status/1471537959421857816?s=20

18/ A more transmissible variant, even if it is less severe can still lead to the same # of hospitalizations in a short time. So, while this trade-off might be good in the long-term, it’s still very dangerous in the short term w/ so many unvaccinated. theguardian.com/commentisfree/…

19/ Great summary of current Omicron studies by @GretchenVogel1 & @kakape:

science.org/content/articl…

20/ ➡️ BOTTOM LINE:

We REALLY HOPE Omicron causes less severe disease. But we don’t yet know.

And “hope is not a strategy.”

21/ By the time we have good evidence of Omicron’s severity, it will be too late to react.

We should all take precautions now to limit spread and boost our immunity through vaccination.

#ExponentialGrowthSucks

22/ Countries with high vaccination rates like the UK saw much lower hospitalization and death rates with Delta compared to previous waves, so we know this can be done.

https://twitter.com/DearPandemic/status/1471622020798500877?s=20

23/ Whether Delta or Omicron, lower severity doesn’t necessarily mean the virus is weaker, but that WE (through immunity) are stronger. #BoostUp #WeCanDoThis

https://twitter.com/davidwdowdy/status/1471878286653468672?s=20

24/ Full post: dearpandemic.org/is-omicron-les…

#scicomm #ThoseNerdyGirls

25/ How could we have forgotten legend @nataliexdean's sketch & explanation of the challenges in measuring severity? 👏👏

https://twitter.com/nataliexdean/status/1468988174693289994?s=20