Health Nerd Profile picture
Epidemiologist. Writer (Guardian, Observer etc). "Well known research trouble-maker". PhDing at @UoW Host of @senscipod Email gidmk.healthnerd@gmail.com he/him
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26 Feb
There's been a lot of discussion recently about preprints and how we should interpret them as evidence

A few thoughts from my perspective as an epidemiologist and science communicator 1/7
2/7 The basic idea of preprints was originally twofold:

1. Put your research in the public domain, get feedback before publication
2. Get research up while it works its way through months/years of peer review
3/7 During the pandemic, given the absurd reality of months+ for studies to be peer-reviewed, preprints have become one of the primary ways for us to see new science

Imo there are pros and cons here
Read 7 tweets
25 Feb
Some fascinating new data on 2020 deaths in Australia from @ABSStats:

- no excess mortality
- a modest (-0.8%) DECREASE in deaths
- biggest driver of the decrease is the massive (-37%) reduction in flu deaths

abs.gov.au/statistics/hea…
Pretty amazing that, despite the spike in COVID-19 deaths from the Victorian outbreak, there was ~no~ excess mortality during winter because the number of deaths directly attributable to influenza fell from a yearly average of ~900 to 42
Also interesting - despite lockdowns and restrictions, at worst only very minor increases in deaths due to diabetes, cancer, or CVD, and a modest reduction in deaths due to COPD (probably flu related)
Read 5 tweets
23 Feb
As an interesting note on this, the last time I contacted an author/editor to point out a study had mathematical errors, I was dismissed by the editor and insulted by the author
Conversely, I've had some really excellent discussions on Twitter about research, people are often happy to engage. Is this unprofessional?
Another important point to think about @apsmunro is that formal channels to critique research take at least months, and can easily stretch to years. The challenge with the status quo is that it often results in no action even for obvious mistakes
Read 4 tweets
23 Feb
The United States recently reached 500,000 COVID-19 deaths

That means the POPULATION fatality rate (i.e. deaths/population) for the US is 0.15%

With an estimated ~25% infection rate, the INFECTION fatality rate is ~.6%
Really puts into perspective how wildly off the earlier estimates of very low IFRs in the US were. An IFR of 0.1% is numerically impossible at this point
Another important piece of perspective is that, in the 12 months from March 2020-March 2021, COVID-19 will likely be the leading cause of death in the US
Read 4 tweets
22 Feb
A new study has hit the headlines claiming that eyeglasses can reduce your risk of catching COVID-19 by "2-3 times:

Unfortunately the science is...not good

Some peer-review on twitter 1/n
2/n The study is preprinted on medrxiv here. It is a single-author study on a survey done in India during COVID-19 medrxiv.org/content/10.110…

This will be a short thread, because...wow. Issues
3/n Some background here - traditionally, in epidemiology, to work out whether something is protective against disease, you need to know two basic things:

1. Likelihood of disease if exposed
2. Likelihood of disease if not exposed
Read 14 tweets
21 Feb
It's not like the CDC has detailed information easily available online about how influenza disease burden is calculated and obtained

Oh wait

cdc.gov/flu/weekly/ove…
The basic issue with influenza surveillance is that, JUST LIKE COVID-19, influenza can cause mild illness similar to a cold

Most people who have an infection don't get tested!
This raises a conundrum. We want to know how much influenza is around, but (based on research) only about 10-20% of people with infections get a test to see if it's influenza or something else
Read 5 tweets
21 Feb
Headline: "COVID-19 pandemic impacts rich people less"

Epidemiologists everywhere: yes, this is true of ALL HUMAN DISEASE. WE'VE BEEN TRYING TO TELL YOU FOR YEARS
It'd be nice if from this global tragedy came a better understanding of the nightmarish social aspects of disease, but my guess is as soon as COVID-19 is gone most people will go back to not caring very much about it
If you want a quick introduction to the topic at a global scale, the @WHO produced this report in 2008 that is still very applicable today

who.int/publications/i…
Read 4 tweets
19 Feb
A very interesting paper on global excess mortality during COVID-19 from @hippopedoid

"...suggests that the world’s COVID-19 death toll may be at least 1.6 times higher than the reported number of confirmed deaths"
medrxiv.org/content/10.110…
Basically, they predicted excess mortality based on previous years using a linear forecast, and capturing seasonal and other variation in mortality
This came up with some very interesting results. For example, here are the excess mortality curves for Australia/New Zealand with #ZeroCovid
Read 5 tweets
19 Feb
The key issue with the Great Barrington Declaration and similar efforts was never about the policy per se, it was the absurd pretence that we could have enormous COVID-19 outbreaks without cost

This was clearly never true
We had more than sufficient evidence by mid-2020 (and earlier) that large COVID-19 outbreaks come with an associated cost. People desperately wanted this to be untrue, despite the very clear reality
And so we got all this obvious misinformation, like the idea that the whole pandemic was just down to false positive results, or that we were all already immune to COVID-19 anyway
Read 6 tweets
14 Feb
This vitamin D/COVID-19 study has gone viral, because the results appear to be impressive and people love promoting vitamin D

Unfortunately, the study itself is...problematic

Some peer-review on twitter 1/n
2/n The study itself is here papers.ssrn.com/sol3/papers.cf…

At first glance, it appears to be a randomized controlled trial comparing calcifediol (vitamin D metabolite) to a control for severe COVID-19 with amazing outcomes (60% mortality reduction 👀)
3/n So, if you only glance at the abstract, you get the picture of an amazing positive result for vitamin D

But reading further, the problems start almost immediately
Read 28 tweets
11 Feb
I love this so I made a few more

WAR OF THE FOOTSOLDIERS: all non-pawn/king pieces are replaced with pawns
CHESSCKERS: you now need to 'hop' over a piece to take it. Captures can be prevented by positioning pieces behind other pieces
CHESSGEONS AND DRAGONS: roll a d20 to move your piece - 1-10 = no movement, 11-15 = move as normal, 16-20 = move twice

All pieces must have names. When taking a piece, describe the epic battle
Read 4 tweets
11 Feb
A lot of people have been talking about it, so I thought I might do a bit of a thread on plausible reasons for the decline in COVID-19 cases in places where behaviour hasn't changed much recently 1/n
2/n The basic background is that there are some places across the world where there hasn't been a reportedly huge behavioural change since Nov/Dec last year where cases are dropping, sometimes quite quickly

So what's causing this?
3/n The explanation proposed by some has been that these places have reached "herd immunity", essentially a threshold where enough people have been infected and recovered such that the disease can no longer spread
Read 20 tweets
9 Feb
This stuff is fascinating. Pay to low-income workers would increase by $509 billion under the bill, but the CBO has assumed that this is a fixed system and that higher wages -> higher prices -> less spending -> fewer jobs
Even more interesting is when you really dig into the weeds. For example, half of all those 'lost' jobs are estimated to be from teens working at the minimum wage
This is a problem that is quite easily solvable. In Australia we have age-adjusted minimum wages for precisely this reason
Read 4 tweets
8 Feb
Always remember the Golden Rule of international comparisons: the most common explanation for a difference between two places is to do with DATA COLLECTION
For example, maternal mortality. Commonly used as a proxy for the wellbeing of a healthcare system

Also, notoriously complex to measure. Here's some examples from the UK, US, and Australia on the measurement
And those are just the top-line statements! The true divergence between the recording across healthcare systems can be massive, because everything from death certificates to doctors' training differs
Read 5 tweets
8 Feb
This is a fascinating example of a complete misrepresentation of risk

- the risk for a 58 year old from COVID-19 is actually quite high (around 1 in 200 risk of death)

- the risk from being inside is complex, but likely minimal
Now, social isolation is harder to assess, and it obviously varies by person, but given the evidence we have on excess mortality in places with long lockdowns that haven't seen a massive increase, it's mathematically impossible for it to be higher than that from COVID-19
Moreover, going out and about during a pandemic has implications for people other than yourself, who may not be aware that you are so blasé about risks
Read 4 tweets
4 Feb
Something that is important to note - despite the somewhat fractious debate about this bad paper, I have not nor will I ever say that closing schools is necessarily a good thing
The issue here is a terrible paper that is wrong in many ways. The scientific community should be shocked and appalled at the actions of journals and authors when mistakes are pointed out in their work
But removing this one impactful study from the literature won't shift the needle that much. The question about opening and closing schools during a pandemic remains, as ever, complex
Read 4 tweets
2 Feb
Haven't done this in a little while, so let's have a spot of fun

Here's a headline in the Daily Mail. It seems...unlikely that this is true

Let's have a look and see
Lest you think I'm being unfair at the dumb headline, here are the next few paragraphs

Finger length impacts your choice of "masculine" or "feminine" foods! Science?
All credit to the Daily Mail here, they do actually link to the study. Wonderful doi.org/10.1016/j.food…
Read 17 tweets
2 Feb
I do find it fascinating how the usual "academic civility/silencing" brigade have completely ignored this whole episode. Apparently it's fine to publicly defame junior colleagues as long as it's in service of school reopening
It's also interesting to note that this is quite literally a case of academic "silencing", at least insofar as the journal and authors have tried their hardest to quash any hint of our critique
Without twitter, and the media attention it brought, I doubt very much that this paper would ever have been corrected. The only reason the authors were forced to respond is that the editors were contacted by the Guardian for comment
Read 5 tweets
1 Feb
If I'm really honest, there is only one characteristic that I've deeply admired during the pandemic, and that is simple:

- Those who can admit when they got something wrong
Thing is, it happens to all of us (I am no exception). It is commonplace to be mistaken, but rare indeed that people will own up to their errors
See, my problem is that everyone thinks that they tick most of the boxes on that list. No one thinks that they're too certain, or ignoring human health, or unkind

We're all the heroes of our own story
Read 4 tweets
1 Feb
The story continues - after @ikashnitsky and I pointed out that this paper was mathematically impossible, and had numerous errors, it was partially corrected

Now, the lead author is calling us "trolls"
His initial response to us, when we privately emailed him about the issue in the paper, was, to quote, "you are not just right because you THINK you are" (caps=italics)
Now, remember, this is not a minor paper

Altmetric of 3,400, in dozens of news articles, and it's been cited by the WHO and EU already

This paper is impacting school reopening policy across the globe
Read 16 tweets
25 Jan
The entire field of epidemiology is about balancing cost and benefit, risk and reward. There is no choice without consequences, even the seemingly trivial ones
Most Master of Public Health courses (MPH) have a health economics unit for precisely this reason. Enacting a policy in one place invariably (at best) takes away resources that you would otherwise use somewhere else
This is a big part of the reason I spend so much time trying to convey nuance. There is no decision we can make for public health that is purely good

There are no silver bullets
Read 5 tweets