Thread by @ToshiAkima

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.