Thread by @ashishkjha

For two months, I've said we're entering a new phase of the pandemic

A phase marked by a lot of population immunity, a more immune-evasive but less virulent virus

This new phase requires new metrics

My @nytopinion piece on the latest CDC metrics

nytimes.com/2022/02/25/opi…

Fundamentally, new CDC metrics get it right

Why?

Because cases no longer are the most important measure

For nearly 2 years, for every 1000 cases, you could reliably predict 50-80 would end up in the hospital and about 15 to 20 people would die

That was true in 2020. And 2021

That tight link between cases --> hospitalizations --> deaths was true for original strain

And for Alpha
And for Delta

But Omicron severed that link (mostly)

Now, if you told me there were a 1000 new cases

I can no longer tell how many will end up hospitalized or dead

3/n

Why? Because if those 1000 cases are in boosted folks -- they will almost all be fine

In vaccinated/unboosted folks? Well, depends on risk profile (40 year-old vs 80 year-old)

And if in unvaccinated people? Not great. At all

So cases along don't tell you enough

We need a more wholistic view

And that's why we need to look at hospitalizations too

And there's one more thing

Healthcare capacity varies widely across U.S.

In some places, hospitals can handle a surge more easily than others

And we know hospital capacity is critical

5/8

Because when hospitals run out of beds

Its bad for patients with COVID

And for patients with heart attacks, car accidents, cancer, appendicitis

Its just bad for public health in that community

So a measure of hospital capacity is also critical

6/8

This is why I like the CDC measures

It brings together what we care about: infections (cases), severe disease (hospitalizations) and hospital capacity

Is it perfect? No

Hospitalizations are a lagging indicator

And they don't incorporate community vaccination rates

But..

7/9

But, a low vaccination community will see spike in hospitalizations after an outbreak in a way high vax community won't

So its implicitly in there

Over time, I'd like to see more on disease dynamics (cases rising or not, how quickly)

And new data sources (wastewater!!)

8/9

But these new metrics mark an important shift

Because when we see future surges or variants

It'll be in a population with a lot of immunity -- from vaccinates and prior infections

And that means looking at cases alone won't be enough

A wholistic approach is better

End