Thread by @ASlavitt

COVID Update: Vaccine boosters appear to double the effectiveness of vaccines against Omicron.

But with only 14% of the country boosted, we should brace for a tough winter. 1/

Studies in the UK and SA are coming back with a consistent finding.

Prior Delta immunity is not preventing Omicron. Re infection rates are at least triple Delta.
2 Pfizer vaccines (presume same for Moderna) have a 30-40% efficacy against Omicron. 2/

Some good news. In both cases (prior immunity & 2 vaccines), studies are showing T cell response (our line of defense that prevents more severe illness in the lungs) continues to work against Omicron. 3/

But the really good news comes from the study of boosters. The 30-40% effectiveness of 2 doses becomes 70-80% with a booster.

Boosting J&J and Moderna with an mRNA should have the same impact. 4/

This is the kind of news that warrants big sighs of relief. It implies that boosters are also effective in breaking the chain of transmission.

So a boosted population would be well protected against Omicron— not even accounting for masks, tests & therapies. 5/

The difference between anticipating a wave this winter with a strong tool to fight it vs last winter when we didn’t is night and day. Or it should be. 6/

Only 14% of Americans are boosted. And while the number of booster shots has increased since Omicron, we are adding only 1% of Americans every 3 days.

Let’s see how that plays out…7/

Omicron is growing at a reproductive rate of 3, which happens to be about 3 times as fast as Delta. Omicron cases are poised to double in the US every 3-4 days. 8/

Delta is doing enough of a job infecting and killing people that it doesn’t need any help.

Pre-Omicron, we’re losing 1200 people/day, 120,000 new cases. These are lion’s share unvaccinated people, never mind boosted. 9/

But Delta is about to get major help from Omicron. 86% of the population is in effect ready kindling for this fire. 10/

Many who aren’t boosted don’t have a choice in the matter. Those under 16 for example. We need to boost everyone around them. 11/

There’s some hope that the Omicron wave will result in fewer hospitalizations/person infected. That would be nice. It’s even probable since we know our t-cell response will protect those of us with prior infection & who have been vaccinated better than say last year’s wave.12/

But we will be talking about very large numbers of infections and cases. And on top of a bad Delta wave.

Even with lower hospitalization rates, many of our hospitals will fill up again. 13/

We also likely have a series of outdated policies that protected us from Delta but won’t from Omicron.

Vaccine mandates at hospitals are for 1 or 2 shots, not 3. Travel to the US requires vax but not boosters. These holes will cause more spread. 14/

Let’s talk about response.

Because deaths will be unevenly distributed, broad policies will be harder to implement— but important given how easily spreadable the virus is. 15/

I’ve talked to several states who are preparing to roll out indoor mask requirements and take other steps to prevent infection.

Others aren’t contemplating major changes. Others will be resistant & others still reactionary. 16/

To the question of whether we face something like a shutdown of any businesses, the balance community by community will most commonly be determined by what happens with ICU capacity. 17/

Even 25% booster coverage, which is where we would be in 30 days if we keep the current pace, will not be enough on its own to hold back an onslaught of cases & likely hospitalizations. 18/

A great synopsis of the science of Omicron and what we know is what @trvrb and I covered, out today. 19/

podcasts.apple.com/us/podcast/in-…

It seems clear that given the great results of the booster, we likely won’t need an earlier Omicron-specific booster.

We do need arms, however. /end