New UK Mask Study Fails In It’s Intention
Professor Carl Heneghan of the Centre for Evidence Based Medicine at Oxford University has just tweeted the results of a sizeable multicentre randomised trial into mask effectiveness (29 centres, 1009 subjects).
I noted that they’d done something sensible and that is to compare performance of ear loop masks (a.k.a. surgical masks) with full-on N95 respirators (proper-job PPE), so I grabbed my morning lemon tea and smacked the link in eager anticipation.
I should not have bothered for here’s the rather thin conclusion:
It is uncertain if medical masks offer similar protection against COVID-19 compared with N95 respirators.
Although outcome measures were rigorous (nasal swab & serum, RT-PCR assay with Ct value (hurrah!), EUROIMMUN assay, symptom record, absenteeism, self-report, care history, adherence to mask protocol audits, social interaction etc etc) a rather frail attempt was made to account for background risk of infection and levels of environmental exposure.
Yes, they looked at contact with with declared COVID cases both at home and in the hospital setting but that relies on a reliable memory and other people openly declaring their health status without error.
What about undeclared cases and folk who haven’t figured that their snivel is, in fact, mild COVID?
How about all those folk with nothing more than a sore throat who think they’ve got COVID as a result of a false positive test result?
How do you assess the infection status of the twenty people queuing up for a kebab with you?
Thus, we find that the most important covariate of all is distinctly lacking in value and robustness.
Neither was an attempt made to compensate for disease prevalence which would have varied over time and differed between centres.
This is a great shame and a golden opportunity to settle the mask matter has been lost.
Then again, I can’t honestly think of a decent, cheap and easy way in which we can properly and accurately adjust for personal exposure to virions, and therein lies the weakness of all mask studies.
About the author: John Dee (not his real name) is a former British government G7-level scientist who now uses his analytical skills to highlight where the public is being lied to on various subjects.
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Saeed Qureshi
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Medical facilities should not be doing testing for mask effectiveness. This is because the results will be inconclusive and irrelevant.
Masks evaluation can ONLY be done scientifically and accurately in an analytical (chemistry) laboratory with a simple experiment.
See here why such an experiment has not been done or why it is impossible to assess mask efficacy. (https://bioanalyticx.com/face-masks-and-covid-19-scientific-reality/).
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NecktopPC
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Conclusion: The N95 filtering face piece respirators may not provide the expected protection level against small virions. Some surgical masks may let a significant fraction of airborne viruses penetrate through their filters, providing very low protection against aerosolized infectious agents in the size range of 10 to 80 nm.
https://pubmed.ncbi.nlm.nih.gov/16490606/
Thirty nine patients (23 men; mean age, 57.2 years) were recruited for participation in the study. Seventy percent of the patients showed a reduction in partial pressure of oxygen (PaO2), and 19% developed various degrees of hypoxemia. Wearing an N95 mask significantly reduced the PaO2 level (101.7 +/- 12.6 to 92.7 +/- 15.8 mm Hg, p = 0.006), increased the respiratory rate (16.8 +/- 2.8 to 18.8 +/- 2.7/min, p < 0.001), and increased the occurrence of chest discomfort (3 to 11 patients, p = 0.014) and respiratory distress (1 to 17 patients, p < 0.001). Baseline PaO2 level was the only significant predictor of the magnitude of PaO2 reduction (p < 0.001).
https://pubmed.ncbi.nlm.nih.gov/15340662/
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Kevin Doyle
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John Dee,
Thank you for the well written article.
In basic, simple language,the reason masks don’t stop a virus is because of size. Surgical masks stop the spread of bacteria. Bacteria are huge compared to tiny viron.
Relative comparison, bacteria are the size of an elephant. Surgical masks are similar to a cargo net. The ‘cargo net’ surgical mask captures bacteria, if hugging your face entirely.
Same analogy, a virus is the size of a mouse. Mouse walks right through cargo net with ease…
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