I have degrees in chemical and biomedical engineering from a fine university as well as over 35 years of experience that included R&D work and complex models. I'm not familiar with BRAD models but I am confident I will be able to understand you despite your brilliance.
I read through the first couple of studies from China and found they lacked the details of the methods and that the conclusions did not necessarily follow from the published data.
I will read the remaining studies today.
You didn't respond to the study I referenced stating that masks cannot be shown to be effective in even in preventing infections in hospitals even in surgery. This study is one of many studies reaching a similar conclusion.
I copied these from James Fetzers' website. There is even a China based study that reaches the same conclusion.
Studies of Surgical Masks Efficacy: Masks are useless in preventing the spread of disease (even during surgery) - James Fetzer
- Ritter et al., in 1975, found that “the wearing of a surgical face mask had no effect upon the overall operating room environmental contamination.”
- Ha’eri and Wiley, in 1980, applied human albumin microspheres to the interior of surgical masks in 20 operations. At the end of each operation, wound washings were examined under the microscope. “Particle contamination of the wound was demonstrated in all experiments.”
- Laslett and Sabin, in 1989, found that caps and masks were not necessary during cardiac catheterization. “No infections were found in any patient, regardless of whether a cap or mask was used,” they wrote. Sjøl and Kelbaek came to the same conclusion in 2002.
- In Tunevall’s 1991 study, a general surgical team wore no masks in half of their surgeries for two years. After 1,537 operations performed with masks, the wound infection rate was 4.7%, while after 1,551 operations performed without masks, the wound infection rate was only 3.5%.
- A review by Skinner and Sutton in 2001 concluded that “The evidence for discontinuing the use of surgical face masks would appear to be stronger than the evidence available to support their continued use.”
- Lahme et al., in 2001, wrote that “surgical face masks worn by patients during regional anaesthesia, did not reduce the concentration of airborne bacteria over the operation field in our study. Thus they are dispensable.”
- Figueiredo et al., in 2001, reported that in five years of doing peritoneal dialysis without masks, rates of peritonitis in their unit were no different than rates in hospitals where masks were worn.
- Bahli did a systematic literature review in 2009 and found that “no significant difference in the incidence of postoperative wound infection was observed between masks groups and groups operated with no masks.”
- Surgeons at the Karolinska Institute in Sweden, recognizing the lack of evidence supporting the use of masks, ceased requiring them in 2010 for anesthesiologists and other non-scrubbed personnel in the operating room. “Our decision to no longer require routine surgical masks for personnel not scrubbed for surgery is a departure from common practice. But the evidence to support this practice does not exist,” wrote Dr. Eva Sellden.
- Webster et al., in 2010, reported on obstetric, gynecological, general, orthopaedic, breast and urological surgeries performed on 827 patients. All non-scrubbed staff wore masks in half the surgeries, and none of the non-scrubbed staff wore masks in half the surgeries. Surgical site infections occurred in 11.5% of the Mask group, and in only 9.0% of the No Mask group.
- Lipp and Edwards reviewed the surgical literature in 2014 and found “no statistically significant difference in infection rates between the masked and unmasked group in any of the trials.” Vincent and Edwards updated this review in 2016 and the conclusion was the same.
- Carøe, in a 2014 review based on four studies and 6,006 patients, wrote that “none of the four studies found a difference in the number of post-operative infections whether you used a surgical mask or not.”
- Salassa and Swiontkowski, in 2014, investigated the necessity of scrubs, masks and head coverings in the operating room and concluded that “there is no evidence that these measures reduce the prevalence of surgical site infection.”
- Da Zhou et al., reviewing the literature in 2015, concluded that “there is a lack of substantial evidence to support claims that facemasks protect either patient or surgeon from infectious contamination.”
Who is ignorant? Not me.
