Thread by @ASPphysician

A few thoughts on the anticipated Omicron wave:

1/ People are increasingly fed up with COVID, so measures to control Omicron cannot/should not rely on measures used for prior waves. (Which means that governments would be wise not to allow COVID to reach a crisis situation.)

When I highlighted several days ago that case growth was worrying me, several Twitterati assumed that I was alluding to lockdowns. (I was doing nothing of the sort)

But failure to pay attention to cases in EUR shows that countries can be forced into lockdowns if they don't act.

2/ Engineering/environmental controls (e.g. ventilation, filtration) will be the smallest imposition on people's lives.

Better masking (understanding, adherence, quality) would make a difference.

This is without assuming any properties of Omicron.

3/ Full vaccination (i.e. 2 doses until 5-6 months, and then a 3rd) will help with Delta, and probably help with Omicron but how much remains unknown.

This requires govt. and media commentators to unequivocally state that vaccination requires a 3rd dose after 5-6 months.

As highlighted in a thread today, Israel relied on 3rd doses to keep their society open during a Delta wave.

https://twitter.com/VincentRK/status/1467524619112386565?s=20

4/ There is a dangerous narrative being circulated that case counts don't matter because of vaccination. It is being amplified by speculation that Omicron will be ok because it causes milder disease.

Vaccination allows us to "tolerate" higher cases but there is likely a ceiling.

5/ If, say, 0.14% of infected people overall died of Delta (IFR) now, then for 5000 cases daily, 7 will die.

Further, widespread circulating virus (Force of Infection) will 📈 likelihood of "finding" the under/unvaccinated, which will thus 📈the effective IFR and📉 VE.

CFR (case fatality rate) isn't exactly the same as IFR, but they are related. Tough to know if CFR has recently gone up in some EUR countries because of waning immunity, FOI, Delta, or decr low-risk testing. But the very recent incr is real. Nordic countries give our best look.

The relationship of VE to FoI was nicely shown by David Kaslow (nature.com/articles/s4154…) with a variety of different real-life non-COVID vax scenarios.

So if we want to optimize VE, it is not only 3rd doses, but keeping case counts under decent (whatever that is) control.

A hint of this comes from comparing 🇰🇷 & 🇯🇵. Their vaccine rollout was comparable, with comparable stringency. Neither should have been susceptible to waning immunity effects yet.
🇯🇵 summer wave was likely due to insufficient vaccination. 🇰🇷 likely Delta + less stringency -> FOI.

6/ This is all difficult to communicate to a fatigued public and—if Omicron is indeed substantially more transmissible—governments will need to carefully communicate the risk.

At present, at least in Ontario, there seems little interest from the government to talk COVID at all.

7/ I haven't touched vaccine certificates (e.g. covid19-sciencetable.ca/sciencebrief/c…) and rapid testing (e.g. see @michaelmina_lab) because these have been discussed extensively elsewhere.

My bottom line:
- we need to avoid instituting any measures that meaningfully reduce personal freedoms
- cases continue to matter
- maximize vaccinations incl. 3rd dose
- governments should remind people that, sadly, COVID isn't over
- there is +++ uncertainty with Omicron

/Fin