Health Nerd Profile picture
23 Mar, 17 tweets, 4 min read
People often make the claim that, during the COVID-19 pandemic, we have "failed to protect the elderly"

While initially this was definitely true (April/March 2020), I'm not sure the claim is accurate past that 1/n
2/n I'm basing my opinion here on seroprevalence data. This is basically data looking at who has antibodies to COVID-19, and therefore who was previously infected

We reviewed 100s of studies for our IFR paper. What did they show?…
3/n Well, not all of them looked at the age-stratified rates of infection

But of those that DID, an interesting pattern emerges
3.5/n (Note: this is excluding low-quality seroprevalence estimates with selection bias issues. These cannot be trusted to give us an accurate estimation of infection rates by age)
4/n For example, take REACT-2, a massive antibody prevalence study from the UK

They found substantially FEWER people had been infected in older age groups than younger ones
5/n If you look at our supplementary appendix, where we give age-stratified prevalence figures for every study, you see a similar pattern in many places...
6/n ...with some VERY notable exceptions!

But remember, these are seroprevalence estimates taken in Italy and Spain in April 2020
7/n Indeed, places that were hit really early on seem to show the opposite pattern

Here are the results for the small Italian town Castiglione D'Adda. Older people were MORE likely to be infected
8/n But that's the thing - in the very early epidemic, people did not protect the elderly

However, what the evidence appears to show is that this was a relatively short-lived phenomenon
9/n While this is somewhat speculative (mostly my opinion) I think it's fair to say that after the tragedy of the early first wave, most places implemented policies that substantially reduced the number of COVID-19 infections of elderly people
10/n All over the world, people took more care with their grandparents, aged care centres curtailed visitation, and generally we were all more aware of the danger to the elderly
11/n This is seen in the numbers - many places that were hit even a few weeks later than Italy/Spain had lower infection rates in older people than younger
12/n Even within countries, I suspect there may have been an impact

For example, New York had ~some~ reduction in infection in older people, but Utah had a big reduction
13/n Like I said, all of this is pretty speculative. It's hard to say how much we managed to protect older people because often the seroprevalence data is not very good
14/n That being said, when we look at good quality seroprevalence estimates, in almost all cases after the initial surge it looks like we did in fact protect elderly people (at least to some extent)
15/n Yes, elderly people have died more from COVID-19, but that's an obvious consequence of the age-stratified IFR. If lots of people get infected, lots of old people will be infected by default
16/n I think it is reasonable to say that in most places we HAVE protected the elderly to a great degree, and we have still suffered the consequences when the pandemic got out of control

• • •

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

Keep Current with Health Nerd

Health Nerd 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!


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 @GidMK

22 Mar
The somewhat depressing fact is that making COVID-19 predictions is essentially cost-free

No one will hold you accountable for predicting wrong, if they even remember in a few months time
The reality is that most people who have predicted the future of COVID with any certainty have made a lot of mistakes, but no one ever checks back to audit those in any meaningful way
There are people who get massive media attention once a month when they confidently predict that COVID-19 will be over in 4-6 weeks time, even though they've been doing it for over a year now
Read 5 tweets
21 Mar
It's not like this is something most infectious diseases epidemiologists have been saying since March last year

Oh wait
Herd immunity through natural infection was always an absurd idea that made no sense whatsoever

Herd immunity through population vaccination is more complex
This is something covered in the John Snow Memorandum quite well, actually. There's no guarantee that immunity (even vaccine-induced) will last sufficiently long to ensure herd immunity
Read 7 tweets
18 Mar
Very interesting study out of Denmark looking at SARS-CoV-2 reinfections:

- 0.65% symptomatic reinfections after 7 months
- in sensitivity analysis this doubled to 1.2%
- estimated ~80% short-term protection against reinfection Image
Studies like this make me very jealous of my Nordic colleagues. The authors had access to linked data for *the entire country of Denmark*, which is a pretty enormous strength of the research Image
Basically, they looked at every PCR test done in the first wave, and followed up every person to see if they had tested positive in the first, second, or both waves

Of those in the sample, 0.65% were infected twice
Read 7 tweets
17 Mar
Something I think about a lot is that studies don't get retracted because they're bad, they get retracted because they are famous
Don't get me wrong, they are ALSO bad. It takes a truly awful study to get a scientific journal to wrest itself free of apathy and inertia to take some action

But there are 1,000s of woeful papers
Thing is, no one is paid to catch bad research. It is a thankless, time-consuming task that at best earns you the mistrust of most of your peers

And so, no one does it methodically
Read 9 tweets
16 Mar
You may have seen the massive viral tweets about how staying at home doesn't prevent COVID-19 deaths

These were based on a paper with what we think are quite significant flaws

Our full critique now preprinted here:
The basic explanation here is that the original article looked at whether Google "residential" mobility data was correlated with COVID-19 death rates, and found no association
There are significant drawbacks with that methodology, some of which I outlined in a thread

Read 8 tweets
15 Mar
Your daily reminder that "I'm pro-vaccine except for THIS one" is literally the most common anti-vax line there is
The second most common line is "I'm pro-vaccine but I'm also pro informed choice" usually followed by a slew of lies and misinformation portraying vaccines as dangerous
So many replies missing the point. There's a big difference between common talking points and actions - most anti-vaccine advocates SAY they are only against one vaccine but then come up with similar arguments against ALL of them
Read 4 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!