Wes Pegden Profile picture
17 Oct, 10 tweets, 3 min read
A common feature of the epidemic modeling that was done to justify untargeted containment efforts was an assumption that transmission reductions could be maintained as long as necessary; e.g, that successive lockdowns would be as effective as the 1st.
1/10
nytimes.com/2020/10/17/us/…
In our article with @ChikinaLab in March, we called for epidemic modelers to make explicit their assumptions about the time-frame on which mitigations would be necessary (for example, so that the correctness of the assumptions could be discussed). 2/10

medium.com/@wpegden/a-cal…
We suggested that maintaining suppression efforts on a timescale of years would take "extraordinary compliance" from the public.There does not seem to have been enough of a realistic appraisal of the durability of this compliance, or the timescale on which it would be needed.3/10 Image
There are different lessons you could take from the realization that compliance with mitigations is a limited resource. They all involve view the early time-frame of the pandemic as an exceptionally valuable one from the standpoint of having an effect on outcomes. 4/10
This is the period when policy can have the greatest impact, for example, on the age-distribution of the population that will eventually have immunity from previous infection.

It is also a timeframe which could be used to deploy other measures, like test+trace or other... 5/10
infrastructure, sufficient to control the epidemic even without high levels of compliance from the public.

But it's not just enough for these things to be better than nothing; they have to be good enough to work with a *sustainable* level of compliance from the public. 6/10
But evaluating pandemic response from a framework where compliance itself was a limited resource never took off.

Certainly, when we don't have good reason to believe that new developments will soon make containment sustainable without great sacrifice, ... 7/10
we find ourselves in a regime where age-targeted measures, which have a powerful effect on mortality in the face of future transmission increases (accounting for realistic contact patterns), may well be the best option to reduce mortality. 8/10

journals.plos.org/plosone/articl…
Better options may well exist.

But the case that an alternative is better involves realistic assessments of the durability of compliance, of the timeframe on which the alternative can be deployed, and of the likelihood the alternative will suffice to contain the epidemic. 9/10
The new waves of infection we see in Europe and the US will eventually come down, controlled either by immunity or new mitigations.

When they do come down, we should do what we should have done in the spring; think about our options with a realistic view of the future. 10/10

• • •

Missing some Tweet in this thread? You can try to force a refresh
 

Keep Current with Wes Pegden

Wes Pegden Profile picture

Stay in touch and get notified when new unrolls are available from this author!

Read all threads

This Thread may be Removed Anytime!

PDF

Twitter may remove this content at anytime! Save it as PDF for later use!

Try unrolling a thread yourself!

how to unroll video
  1. Follow @ThreadReaderApp to mention us!

  2. From a Twitter thread mention us with a keyword "unroll"
@threadreaderapp unroll

Practice here first or read more on our help page!

More from @WesPegden

15 Oct
We have entered Phase II (or is it XXII?) of the COVID "discussion": gathering signatures for petitions.

In some sense it is the perfect phase for this moment, which involves remarkably little scientific curiosity or engagement.

Some thoughts. 1/17
First let's consider the GBD. This document lays out in concise terms the position that COVID mitigations should focus on vulnerable populations. 2/17

gbdeclaration.org
It advocates for the one of the most extreme (not a synonym for ridiculous) positions of this form, which is that "life as normal" should immediately resume for younger people.

My least favorite thing about the GBD...
3/17
Read 17 tweets
26 Sep
The attention-grabbing data shown in this Bloomberg article is data described as being collected from "1500 patients".

bloomberg.com/graphics/2020-…

In fact, recruitment to this study was done via the social media post shown below.

The long-term burden of COVID infections is... 1/4
an important scientific question.

We are not making progress on this question by overemphasizing the role of anecdotes

There is no technical reason why this cannot be answered using a scientific approach. A random sample of past COVID+ patients should be surveyed... 2/4
and examined at 3 months, 6 months, etc, and proper comparisons should be made (e.g., to other respiratory infections).

We are 9 months into the pandemic.

The importance we place on this problem should be reflected in the seriousness with which we approach it. 3/4
Read 4 tweets
25 Sep
Age-targeted strategies are often interpreted in extreme ways: "cut off", "perfectly segregate", etc, some part of society, while everyone else "gets on with normal life".

Obviously in this formulation, skepticism is merited. Nothing is perfect, and "cutting" things off...1/9
sounds hard!

But this is an absolutist interpretation of ideas which should, like most, be interpreted quantitatively. The same misinterpretation could be given for all current strategies, by suggesting that masks, restrictions, etc., aim to "perfectly" stop all transmission. 2/
In fact, the goal of current strategies is to have a quantitative effect on transmission, reducing it for all groups essentially "as much as the market will bear".

In practice, this has involved implementing policies which begin harshly (lockdown), and gradually relax. 3/
Read 9 tweets
20 Sep
A quick note on this thread by @joel_c_miller before bedtime.

Joel is summarizing a nice argument coming from random graphs to suggest that increasing transmission rates among low-risk groups cannot be good, unless accompanied by other decreases. 🧵 1/9

This argument is valid if comparing two scenarios with constant transmissions. It is not valid if we expect (as I think we do!) that transmission patterns will eventually increase.

In particular, it is worth noting, that... 2/9
even in the simplest single-population models with time-varying transmission rates, epidemic sizes (and thus mortality) can be decreased by increases in transmission.[🤯]

Time dynamics make coupled systems complex, and intuitive reasoning about the effects of changes is tricky.
Read 12 tweets
17 Sep
In our paper w/ @ChikinaLab we
1) account for preferential mixing in age groups
2) do not require perfect isolation of at risk groups
3) do not assume that we can "turn off transmission" (indeed, we assume transmission gradually reverts to normal levels)1/
Joel is also concerned that aged-care facilities could support an epidemic (not localized outbreaks at individual centers) on their own without any involvement of younger individuals (staff/doctors/etc). 2/8

An earlier discussion on this ended abruptly:
I think its fair to say this is an unusual viewpoint.

Threads like this which dismiss age-targeted strategies out of hand inevitably work with the most simplistic and absolutist version of an idea. I have not seen an argument that we cannot have a quantitative... 3/8
Read 8 tweets
13 Sep
This commentary on herd immunity thresholds is making the rounds today. There is nothing new in this article, and parts of its commentary are quite misleading. It is worth thinking about why a commentary like this is widely shared by scientists.
🧵
1/11

nature.com/articles/s4157…
I worry that the ways in which the article is misleading is, in fact, precisely why it is widely shared.

E.g., they sow doubt for infection controlled immunity, suggesting that "several rounds of re-infection" might be needed to generate robust immune responses. 2/
This is not a reasonable level of uncertainty to apply in an article that also discusses vaccine-induced herd immunity as an inevitable eventuality.

Although they explain some of the mechanisms which can lower HIT's, they also say misleading things, e.g. that HITs are only... 3/
Read 19 tweets

Did Thread Reader help you today?

Support us! We are indie developers!


This site is made by just two indie developers on a laptop doing marketing, support and development! Read more about the story.

Become a Premium Member ($3/month or $30/year) and get exclusive features!

Become Premium

Too expensive? Make a small donation by buying us coffee ($5) or help with server cost ($10)

Donate via Paypal Become our Patreon

Thank you for your support!

Follow Us on Twitter!