Will we reach herd immunity?

We might. In some places. For periods of time

And not sure it matters that much

Experience from UK, Israel clear

Get enough folks vaccinated, pandemic fades into the background

My latest in @PostOpinions

washingtonpost.com/outlook/2021/0…
Few points from the piece:

1. herd immunity threshold varies based on variant of SARS-CoV2, vaccination rates, prior infection rates, who has immunity, so forth

2. Herd immunity not a one and done. We've had HI for measles. Then vaccinations fade -- and it pops back up

2/3
3. Herd immunity does not eradicate the virus

4. Some places in the US have high degree of immunity and likely will hit herd immunity with more vaccinations. Others won't

So here's the bottom line:

This pandemic will end here in the US even if the virus isn't gone

3/4
How can pandemic end if virus still around?

Pandemics end when risk they pose and strategies needed to mitigate that risk, fade into background and become part of normal life

As saying goes, pandemics end with a whimper, not with a bang

This one, too, will end

With a whimper

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More from @ashishkjha

9 May
India reports another 400,000+ cases, 4000+ death day

A sustained level of horribleness

And its not correct

True number surely closer to 25,000 deaths, 2-5 million infections today

Lots of ways to estimate but here's a simple one

Look at the crematoriums

Thread
During non-pandemic year 2019

About 27,000 Indians died on typical day

Crematoriums handle that level of deaths every day

Additional 4,000 deaths won't knock them off their feet

Crematoriums across the country reporting 2-4X normal business

2/4
So best estimate 55K to 80K people dying daily in India

If you assume baseline deaths of 25-30K

COVID likely causing additional 25K to 50K deaths daily

Not 4,000

What about infections?

Lets start with Infection Fatality Ratio (IFR)

In India, at least 1% right now

3/5
Read 6 tweets
3 May
Folks being critical or misunderstanding this very good @apoorva_nyc piece

5 points that this piece pulls together nicely

1. Last year, we all assumed herd immunity threshold (HIT) would be 60-70%. Now clear its higher

This is not tragic

Thread

nytimes.com/2021/05/03/hea…
2. HIT may be 80%. Seems high

But its possible we might get there. We're about 60% population immunity now

As we improve access, make vaccinations easier, open up to kids, will get into the 70s

3. HIT not an on/off switch. Its not like we hit 80% and disease disappears

2/4
Already, we are seeing high levels of population immunity have large effect on dampening cases

My thread from yesterday:



States like RI, MA, SD already at 70% population immunity. They might get to 80% before long

covid19dashboardgt.shinyapps.io/us_immunitylev…

3/5
Read 5 tweets
2 May
At what point should we see cases in US begin to drop sharply from vaccinations?

Complicated but experience from Israel says 45-50% of population vaccinated

US is shy of that

But some states past that threshold

So do we have evidence its working there?

Why yes we do

Thread
Lets look at top 5 vaccinated states

NH, MA, CT, VT, ME

All >50% of population 1+ dose

So what's happening with cases (c/w 2 wks ago)?

NH down 44%
MA down 37%
CT down 40%
VT down 46%
ME down 42%

I know, all New England states

Lets look broadly at cases & vaccinations

2/4
If we take the 10 states with largest drop in cases

Average vaccination rate 49.8%

The 10 states where cases actually rising?

Avg vaccination rate 39.9%

It appears somewhere around 45-50% population vaccinated (65% or so adults vaccinated)

cases really turn down

3/4
Read 4 tweets
26 Apr
While the world is struggling with the pandemic, things here in the U.S. have turned decidedly better

And that's very helpful

Let's see where we are:

Infection numbers fallen below 60K/day for first time in a month

This time, I think it'll stick

Why?

Vaccines!

Thread
Last time the US got below 60K/day, we started rising again

How do we know that won't happen now?

Because in mid-March, when last mini-surge began, 21% of the population had been vaccinated

Today, we're twice that

Is 42% getting at least 1 shot enough?

Of course not

2/4
But 42% close to number at which we should see steady declines in infections

In Israel, once 45% of population was fully vaccinated, case numbers started to plummet

Several U.S. states approaching that

So while some states may still struggle, we should be on a better path

3/4
Read 4 tweets
15 Apr
CDC's vaccine advisory committee ACIP met today to advise on J&J pause

After thoughtfully discussing what we know & don't know about rare clotting events, they punted

The advisory committee decided not to advise

This was a mistake. J&J should be un-paused soon

Thread
Initial pause by FDA on Tuesday was a close call

But I supported it

A few days to alert people, begin process of collecting more data, advise physicians -- all made sense

Now advisory panel wants to return in 7 - 10 days to discuss further

The risk-benefit here is all wrong
Nearly all the adverse events are in women 18-49 years old

Cerebral Venous Sinus Thrombosis (CVST), the clot seen with J&J, is known to be more common in young women

Suggests that young women probably the group at high risk

This actually gave ACIP a smart way forward

2/7
Read 9 tweets
10 Apr
What's the state of the pandemic in the US?

In last month

B.1.1.7 and other variants have become dominant

90M vaccines have gone into arms

Cases are up about 20%

Here's the key graph for US since Feb 1

Its a Rorschach test

I see it as mostly good news

Thread
Obviously state of pandemic varies widely from state to state (e.g. Michigan)

But here are the 5 largest states in US (by pop)

35% of Americans live here

NY high, slowly drifting down

FL, PA rising slowly

CA, TX low, staying there
And a few other things have happened

77% of people >65 have had at least 1 shot

44% of all adults too

And given this, I think we are likely to avoid a serious 4th wave

That doesn't mean we won't see spikes (see Michigan)

Or that we are at Herd Immunity (we aren't)

3/5
Read 6 tweets

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