So I've got a new preprint out. medrxiv.org/content/10.110… developing mathematical disease models that are appropriate for ethical analysis.

Most of the work done by Daniel Roberts. Help from @ID_ethics, George Heriot, Michael Selgelid, and Anja Slim 1/22 There's some beautiful mathematics in it, but I'll save that for a different thread. Here I'm going to focus on the results.

Our goal is to build a framework that lets us evaluate the ethics of policies for infectious disease policies that try to enforce compliance. 2/x

A comment on whether the "Doherty Model" is appropriate if case counts are high when threshold of 70% or 80% is met:

[note - this is my personal opinion without consulting collaborators, should not be taken as official statement of any group I'm affiliated with] These thresholds provide valuable guidance to policy makers and the public to help them develop plans, and to see that vaccine is the best tool to get us out of our current predicament.

Why do lockdowns become more important just before or in the midst of a vaccine rollout?

1/n First, let me both dispel and validate one criticism of lockdowns: "you're just delaying the infections - they will happen later"

2/n

In the thread below, the claim is made that COVID-19 is only hypothetically worse than common cold and that the deaths are a result of lockdown and fear rather than COVID-19.

Let's see what data there is to test this...

https://twitter.com/goddeketal/status/1366752754144796674

But, let's clearly state the two hypotheses we'd like to compare and look for the available data and compare their predictions against the data

A) lockdown and fear is responsible for deaths
B) COVID-19 infection is responsible.

Let's talk about how a scientist should make and then test a hypothesis.

https://twitter.com/MLevitt_NP2013/status/1357804286432870400

When one makes a hypothesis, one should look for other, simpler hypotheses which could also explain the data.

In this case, perhaps one might think that the interventions done to control COVID-19 might also control influenza. Since flu has a lower R0, this might be enough.

Some comments on the VIC path to getting its epidemic under control. A 🧵

Victoria hit over 700 cases a day, and now has gotten into single digits per day. When cases first started doubling each week, there were a few relatively mild restrictions put in. I believed at the time it was an appropriate scale of response. Many felt it was an over-response.

@apoorva_nyc This reminds me of the short story that I sometimes wonder about writing up... It would absolutely be panned for over-use of foreshadowing.

My wife, daughter and I live in Melbourne . I was talking to my Mom who lived in Texas. I had commented on it being windy... @apoorva_nyc then I mentioned we were going hiking. My mother responded that I should be careful of falling trees because she knew of a person who had been killed by one.

Sure Mom... will do.

You know that feeling when it's 4am and you've just finished recording a lecture, but the recording still needs to be uploaded? and then you realize that it's 10% too big to upload because the university's system has an arbitrary filesize limit?

A few words of caution to those who would read too much in from this figure that's making the rounds: It is clear that Sweden has suffered similar economic decline to its comparable neighbors, but at a much higher cost in lives, as well as long-term disability.

However...

A 🧵on whether we can protect high risk individuals by increasing infections in low risk individuals. Can it work?

We need to be aware of what assumptions have to be true for this to reduce deaths. First a caveat: I'm focusing on deaths here. There are other things that matter.

If you are arguing for this strategy because of other concerns, that's fine. But too many people suggest this strategy saves lives without understanding what they are talking about.

"We used tongs to pick them up by their tails for measurements, because these scorpions are big and nobody wants to be stung"

https://twitter.com/latrobenews/status/1305316124993626112

When I was 8 or 9 years old, I did a "reading comprehension" test about a reading that involved a child picking up a scorpion by the tail. I got the question wrong b/c apparently I was supposed to realize that "by the tail" was the most dangerous way to pick up the scorpion.

A thread on how the lockdown in Victoria has affected Victoria and Australia. First to anyone who argues that "lockdowns don't work", objective observations disagree.

We need reasonable discussion about whether lockdowns are justified, but if your starting point is "lockdowns don't work", you've disqualified yourself from reasonable discussion.

Since a recent "lockdowns don't have any impact" thread seemed to get some traction (including being retweeted by a friend of mine who is reasonably quantitative), I thought it would be good to revisit the claims in detail. Bit of a long🧵 It makes a compelling argument, if you accept its claims at face value. But if you kick the tires, even the slightest bit, it seems every "factual" statement falls apart.

TFW you get back referee reports for and one says

"the reference list is embarassingly short and hasty... There is no discussion about the many existing models recently proposed for COVID-19..." Every single one of the papers/preprints we are asked to cite did not exist in any publicly available form when our initial preprint appeared on medrxiv (Mar 6).

At least one cites our preprint.

grrrr

<end rant>

It's clear that stage 3 + face masks had an impact. Cautiously, I would say that the current decline in case counts may be evidence that stage 3 + face masks => R<1.

https://twitter.com/COVID_Australia/status/1292602675440189440

I think other states in Australia should be requiring face masks. Sure it feels funny to wear face masks when there is almost no local transmission, but it's a small cost relative to other interventions that may be required if it does establish.

I'm not sure I believe the 10% level, but I would not be surprised at all if NYC with 25%ish or so recovered + masks and decent social distancing would maintain effective reproduction number <1, even over winter.

https://twitter.com/mgmgomes1/status/1291162358962937857

@mgmgomes1 's work really does seem compelling, and definitely worth close followup.

I wonder about doing some sort of innovative snowball sampling to identify the seroprevalence among typical contacts rather than typical individuals.

I've seen the argument made, most recently in a referee report, that

"employers should be implementing a correct, effective hierarchy of controls in which PPE is a last-resort element—not a first line of defense against infection among workers" Can anyone make sense of that for me?

Perhaps also point me to a place that has successfully implemented that hierarchy of controls without turning to that "last-resort" element?

VIC introduced major interventions when cases were generally under 100 a day. Now it's frequently over 400 a day. If NSW waits until 250 a day to respond, they can expect to reach 1000 a day within a couple weeks.

smh.com.au/national/nsw/c… Wisdom could be defined as learning from the experience of others.

Many places have not shown wisdom.

China had a massive outbreak.

Italy & Spain saw China but thought they were different and assumed they could be patient on their response. They had massive outbreaks.

A new paper is out exploring the impact of heterogeneity on the herd immunity threshold.

It explores two types of heterogeneity
- variation in susceptibility
- and variation in contact rate. medrxiv.org/content/10.110… It reaches a surprisingly low value (~10%!!) for the potential herd immunity threshold under infection-acquired immunity.

The reason that infection-acquired immunity is highly effective when these heterogeneities exist is that infection acts like a targeted vaccine.

This is hugely concerning. There's the obvious "personal responsibility" argument.

But there are other messages that we need to take from it.

https://twitter.com/CaseyBriggs/status/1285768043293892608

There are 2 obvious reasons I can think of why people might not isolate.

1) they're going to lose income or maybe even their job if they stay home.

2) they've been isolating. They aren't feeling bad. And it's been a couple days.

A 🧵regarding facemasks (now required in Melbourne).

We've been seeing 200-400 cases a day for about a week now. I've been wearing a mask in public for a while now. I think they are an important additional step for disease control.