I agree wholeheartedly with the criticism of the way the Conly Cochrane meta-analysis dismissive of masks has been conducted. But—sorry, team—I need to add some wee quibbles from a philosophy of science perspective. 🧵theconversation.com/yes-masks-redu…
The biggest shortcoming of RCTs of respirators is this: where direct mechanistic evidence retains predictive validity, this is the preferred form of scientific evidence. The invalidity of direct mechanistic modelling needs to be proven before falling back on RCTs.
Look at the key occupational PPE worn by this soldier: tactical respirator, helmet, body armour. None are tested by RCT. Some non-clinicians sitting in an office demand RCTs before the *same gear* can be issued to HCW before going into battle against COVID.
Let's look at the filtration component of a military tactical respirator. It protects against the inhalation of hazardous gasses and bioaerosols in chemical and biological warfare. Here is a 3M HF-800 half-mask, which can do much the same thing.
Here are the filter options for the @3MSafety HF-800SD series sold on Amazon. Even the filter for chemical vapours is NIOSH P100 rated against particulates (like asbestos) and bioaerosols. A military tactical respirator is a minor variation of a medical bioaerosol respirator.
Let's take a closer look at that military tactical respirator. You can make out faint EU CE certification markings, probably similar (if not the exact same) CE markings as those conferred to non-military elastomerics.
An elastomeric respirator goes through the same bioaerosol and particulate testing protocols based on EU CE standards as a disposable FFP2 or FFP3 respirator. The physicochemical principles by which they work are also identical.
We don't expect military helmets and body armour to be live tested vs placebo before being declared worthy of issue as military PPE. Nor do we expect military tactical respirators to be live tested vs placebo in a gas or biowarfare attack, prior to becoming standard issue.
Or are we to believe that the toxic vapour filtration (for chemical warfare) and the bioaerosol filtration (for biological warfare) of the *same* NIOSH/CE certified filter should be tested by different standards? One by direct mechanistic testing, the other by clinical RCT?
As with crash-testing helmets, there is no reason that laboratory testing of respirators does not accurately predict outcomes in the real world. Because evidence gained from direct mechanistic modelling retains predictive validity for the real world. helmet.beam.vt.edu
Bioaerosols behave according to the predictive laws of physics. In-laboratory direct mechanistic testing of a respirator can be demonstrated to be predictive of protection against airborne bioaerosols. It is unethical to subject wearers to live RCT testing in biowarfare.
Testing in real-world RCT settings is more likely to introduce confounding from compliance and deployment training issues. If soldiers died before donning respirators in a Novichok attack in Ukraine, would you declare surgical masks just as effective as tactical respirators?
The likes of Conly are useless academics who sit in an office trying to get us frontline HCWs killed and injured by hindering universal access to correct PPE. They have blood on their hands. Thousands of HCWs have suffered from such incompetence.
The majority of science is done by predictive corroborative testing of direct mechanistic modelling without RCTs. For example, Einstein's general theory of relativity predicted gravity waves which took decades before they were definitively confirmed. ligo.caltech.edu/page/what-are-…
Medicine is the black sheep of science, as predictive modelling of drug efficacy is not yet valid. We can't design drugs with direct mechanistic modelling like engineers design bridges. We are reduced to primitive trial-and-error empiricism to see if a drug kills or cures.
In most sciences, direct mechanistic modelling retains predictive validity. We can't generalise from its invalidity in medicine to think the same limitations of predictive modelling apply to aerosol physics, which is judged by the evidence standards of physics, not pharmacology.
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Malaria is vector-borne. How would you hasten the spread of malaria? By telling people to protect themselves against malaria by handwashing instead of using mosquito nets.
HIV is body-fluid-borne. How would you hasten the spread of HIV? By telling people to protect themselves against HIV by handwashing instead of using condoms (or PEP/PrEP)
Cholera is waterborne. How would you hasten the spread of cholera? By telling people to protect themselves against cholera by handwashing instead of boiling their drinking water.
Despite ancient origins, “contagionism” remained deeply unpopular because it implied the need for lockdowns to contain spread. Libertarian miasmatists claimed diseases weren't contagious. They regarded themselves as too modern for nasty Medieval lockdowns.
That's why when Semmelweis came up with the contagionist concept of handwashing to reduce disease spread, the whole libertarian medical world gasped in abject horror.
The idea of explosive contagiousness still terrifies people today. If a virus is airborne, like measles, it implies high-grade contagionism, leading to government to downplay the severity of the eruption: “Oh, it's nothing a dab of hand gel can't fix”.
This article on the outbreak of Cryptosporidium infections in Queensland is riddled with problems and contradictions. abc.net.au/news/2024-02-2…
It states: “Health officials say the spread of the illness can be controlled by proper hygiene and hand washing.” Yet, it also says, “You don't need to get much water in your mouth to potentially get a case.” How does handwashing stop that?
QLD Health claims: “What we saw with СОVID was people taking … precautions and washing their hands and limiting contacts, which led to a suppression of other communicable diseases. It's not surprising that there's a bit of a rebound where people are getting a bit complacent.”
Statements claiming that SARS-CoV-2 can't possibly be airborne because that would imply it is frightfully contagious, with an R0 more like measles, reminds us of how divisive a concept contagionism has been through the centuries. 🧵
Miasmatists held that miasmatism was more modern and libertarian, as opposed to contagionism, which had been used since the Middle Ages to justify quarantines and lockdowns to contain person-to-person transmission.
If you were a miasmatist, you held that lockdown and quarantine were useless since diseases were never contagious from person to person but spread by miasmas. It was your attitude to lockdown that determined whether you were a miasmatist or a contagionist.
A nice photo illustrating why surgical mаsks don't work as respiratory protective equipment. You can see big gaps at the top, sides, and bottom. All the air you breathe in goes through the gaps and enters your lungs unfiltered. Photo from a respirator ad by Koken.
But—you may object—surgical mаsks have excellent particle filtration efficiency (PFE). So they must work…right? A high PFE means nothing if the air you breathe in sneaks past unfiltered through these gaps rather than going through the filter. armbrustusa.com/pages/mask-tes…
This is why mаsks don't work. But there is a device that does work to stop you from inhaling airborne pathogens, and it is formally designated a “respirator” because it is designed to be tight-fitting enough not to allow leaks. #WearARespie
A bit of commentary on this @JAMANetworkOpen paper. It just means that HCWs should get a fresh respirator after they remove their respirators for a meal break mid-shift. Simple. 🧵 jamanetwork.com/journals/jaman…
The mechanism of fit failure is uncomplicated. It is strap fatigue. The reason trifolds didn't last as long is that they were Auras, which have super thin straps. This is not the case with Trident trifolds. It has nothing to do with the facepiece design (cup, duckbill, trifold).
The authors note, “the safety of reuse found that N95 fit was reduced after 5 donnings and doffings”. This is because it stretches the straps, provoking strap fatigue. The solution is to get fresh straps.