Interesting rebuttal here from @VPrasadMDMPH to punches thrown initially by @adamcifu on the new masking RCT

Lots to like in this piece, but I believe Vinay is very wrong about something in a way that is difficult to see

The placebo effect

1/
open.substack.com/pub/sensibleme… Vinay points correctly to the bias prone endpoint of self reported URTI symptoms and implies the entire difference between groups could be due to “the placebo effect”

The problem is, this is almost
certainly not a result of placebo

It’s detection or ascertainment bias

2/

Incredible study 🇳🇴

RCT of surgical masks for reducing respiratory infections

Wearing a mask for 14d reduced onset of symptoms of respiratory infection (OR 0.71, 0.58-0.87)

Absolute risk difference of ~3%

What does this mean?

1/🧵
bmj.com/content/386/bm… First, it shows RCTs of population implementation of interventions like masks is of course possible

In fact it is necessary and important to appropriately determine effect size

2/

New study of paxlovid for Post Acute Symptoms of Covid (PASC - also known as "long covid")

It's quite an interesting study actually

Here are my brief thoughts

1/🧵
jamanetwork.com/journals/jamai… The rationale behind this is that some have postulated PASC could be due to viral persistence - SARS-CoV-2 hanging around when it should have been cleared

Anti-virals might help clear the virus and resolve symptoms

2/

A few interesting points of data which help us to evaluate some theories re Covid

1) RSV season is now ending in England with the most "normal" wave since the pandemic

Covid related immune problems causing more severe RSV is in the bin 🗑️

1/
assets.publishing.service.gov.uk/media/659fe802…
2) Covid may be peaking (possibly plateauing) with the LOWEST prevalence (via mass testing survey) in all age groups being in school aged children

Schools being unsafe, children being disproportionately affected or spreaders of Covid is in the bin🗑️

2/
gov.uk/government/sta…

This article about masking and RCTs is extremely confused and appears to totally misunderstand everything about clinical trials

I will put to one side the dreadful title (which presumably the authors didn't choose) and explain some of the most important errors in thinking

1/ First of all, the idea Science "couldn't" produce the answers we needed is false

We are perfectly capable of producing high quality, relevant clinical trials in this area

We just didn't

There are no excuses for this, it's a massive failure

2/

What's happening with GAS in the UK?

The surge has caused a great deal of anxiety and got a lot of attention

Quick update on the situation following new data and some great new analyses

1/🧵
alasdairmunro.substack.com/p/group-a-stre… Updated data from UKHSA tells us a few things

Firstly, the data on scarlet fever is now not useful, as it basically just represents awareness

Probably massive overdiagnosis at the peak, no idea where it truly is now

2/
gov.uk/government/pub…

It may seem ridiculous this is even necessary, but it actually cuts to the heart of some of the major issues with messaging around mask use

Clearly these persist even today, which is remarkable

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fullfact.org/health/5live-m… Whilst the quality of the evidence around the impact of community mask use is really poor, it’s generally in favour of a modest impact

A *modest* impact

In fact, an impact which is generally imperceptible from statistical noise to the naked eye

2/

With everything going on, it can feel difficult for parents to know when to get their poorly child checked out

My most important tip is to check the AMAZING healthier together website (or app)

what0-18.nhs.uk

What follows are some general tips I give parents in ED

1/ Firstly, it’s normal for them to not be normal when poorly - because they’re poorly!

As a reference, remember when you last had a flu like illness and how you felt

That’s probably how they feel! They will behave accordingly

You’re looking for signs out of keeping with this

2/

Here is a totally uncontroversial thread about immunity to common pathogens as influenced by the pandemic

I will simply state facts

1. Rates of many commonly circulating pathogens almost completely vanished during the first 1 - 2y of the pandemic (eg Group A Strep)

1/ 2. The reason these pathogens almost vanished was because transmission was reduced by the measures which were introduced around the world to reduce transmission of #SARSCoV2

This coincidently also reduced transmission of other pathogens, often even more successfully

2/

Interesting comment here

As a matter of fact, the data suggest this is completely wrong

Let’s look at a few studies comparing protection from covid vaccination vs infection

1/ Because this is twitter, I of course need to start by saying I am not suggesting it is good to get infected

Merely pointing out protection from infection is excellent, and comparable to vaccination

2/

Is the immune system like a muscle? 🤔

Yes actually, in many ways it is 💪

EXCEPT it's not one big "general" muscle

You have specific muscles for each different pathogen, and each of them is a bit different in how quickly/easily it gets stronger or weaker🏋️‍♂️

1/ For some bugs, once you've fought it once, your muscles are so strong against it they may never need another work out to fend it off (e.g. measles, smallpox)

For others, they get weak quite quickly, but get stronger again each time you fight it (e.g. RSV, Covid)

2/

Many are aware of the current high rates of RSV admissions to hospital/PICU

You may not be aware that a substantial number of these are in very young babies, only a few weeks old

The reason why many think this is happening might not seem obvious at first...

1/🧵 Clearly this has nothing to do with covid infections, as the babies are far too young

Also nothing to do with them not having been exposed during the pandemic - they're post pandemic babies

In fact, it's not much to do with *their* immune systems

It's their mums

2/

New from me and @R_Hughes1 in @ADC_BMJ

Face masks for young children (<12) should be avoided in view of lack of evidence of utility and potential harms

1/
adc.bmj.com/content/early/… Most existing evidence used to suggest efficacy of masks in young children is irreparably biased by systematic differences in masked vs unmasked populations

In some studies this is actually explicit, which makes it remarkable people consider it useful evidence

2/

Immunity debt is not a "made up term"

Here is a list of references about immunity debt (also known as Immunity Gap) to share with those who may be confused regarding this term

1/
pubmed.ncbi.nlm.nih.gov/36193913/ 2/
pubmed.ncbi.nlm.nih.gov/34695374/

A request that before tweeting about “immunity debt” that you spent a few minutes reading *ANYTHING* published about it (your friends tweets don’t count)

Most people arguing about it are completely wrong about the basic premise

Let’s explain

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open.substack.com/pub/alasdairmu… It has nothing to do with individual immune systems being generally weaker due to lack of exposure to generic pathogens

It is about total, population immunity to specific pathogens

2/

If you read medical research, the 95% confidence interval is one of the most important results to understand

Chances are, everything you know about it is wrong

There is NOT a 95% chance the true effect lies within any given 95% CI

Why?

1/
open.substack.com/pub/alasdairmu… This characteristic of a 95% CI is based on the frequentist understanding of probability

That means, when repeated over and over again, 95% of them will contain the true effect (under idealised conditions)

So why isn't it true for any given 95% CI?

2/
alasdairmunro.substack.com/p/95-confident…

Some very niche, but very loud parts of twitter claiming the extraordinary surges in childhood RSV are somehow caused by covid

In reality, this phenomenon was first observed in countries which had experienced negligible levels of covid infections, so this is nonsense

1/ Here we have New Zealand

2/
ncbi.nlm.nih.gov/pmc/articles/P…

Think you know what a 95% confidence interval means?

Think again!

Despite being one of the most common results in biomedical research, it’s almost certainly one of the most misunderstood

You were probably even taught it incorrectly

Where did it all go wrong?!

1/ It all stems from a confusion between 2 different philosophies of probability:

Frequentist: how often outcomes occur under repetition

Bayesian: subjective belief of probability incorporating prior knowledge

2/
open.substack.com/pub/alasdairmu…

Whilst there has been an understandable focus on air quality for SARS-CoV-2, the idea that this is obviously transferrable to other respiratory viruses is not necessarily true

For example, lets look at RSV

1/ Studies on hospital transmission of RSV found substantial reductions with the use of glove and gown PPE

Despite the surprising bad press over hand hygeine, guess what?

It's kinda important for many different bugs (and there are more than just covid!)

2/
nejm.org/doi/full/10.10…

Ah

Someone has emailed the whole directorate by accident, immediately recalled the email, yet here is the flood of confused "Reply All" emails asking what is happening or asking to be removed from the trail

It is 2022

My email is pinging with these every 40 seconds

Excellent THERE IS NO TRAIL IF YOU ALL STOP EMAILING EACH OTHER ASKING TO BE REMOVED FROM THE TRAIL

Whilst working in ED over the weekend, we got into a discussion about the drug codeine, an opiate used for analgesia

Unfortunately, codeine is awful

Here is why I don't prescribe codeine, and you probably shouldn't either

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ep.bmj.com/content/101/3/… Codeine is a synthetic opiate

Except the codeine molecule itself doesn't actually exert any analgesic effects

To work, codeine needs to be converted in your body into a different drug - one you might have heard of

Morphine

2/