You actually cited an editorial which simply reflects the opinion of the authors and their own description and interpretation of the actual study. Below is some of the language from that Editorial. Italics throughout this post are my commentary.
Editorial
July 14, 2020
Universal Masking to Prevent SARS-CoV-2 Transmission—The Time Is Now
Although not a randomized clinical trial, this study provides critically important data to emphasize that masking helps prevent transmission of SARS-CoV-2.
Cloth face coverings can substantially limit forward dispersion of exhaled respirations that contain potentially infectious respiratory particles in the 1- to 10-μm range that includes aerosol-sized particles, ( Note that the Covid-19 virus is .12 or roughly one-tenth the lowest part of that range and 1/100th the upper) and recent research of household textiles’ performance when used as source control suggests cloth face coverings may be able to do so with acceptable efficiency and breathability. Others may think it is premature to promote community masking until research has been completed that measures the effectiveness of cloth face coverings to prevent exposure specifically to SARS-CoV-2. Laboratory studies will be difficult and costly because they require capacity to safely manage this biosafety level 3 pathogen. Any type of community-based randomized trial will be complex to deploy in the right setting (a community with active infection) at the right time (when infections are increasing) to produce actionable results quickly. In the absence of such data, it has been persuasively argued the precautionary principle be applied to promote community masking because there is little to lose and potentially much to be gained. In this regard, the report by Wang et al provides practical, timely, and compelling evidence that community-wide face covering is another means to help control the national COVID-19 crisis.
Here though is the actual study upon which those editorial opinions were based and it hardly justifies the sweeping conclusions of the Editorial or the CDC. Note the relatively small decline from universal masking and note also the potential confounding factors. Remember too that this is a hospital-based study and the masks in use likely were N95 respirators.
July 14, 2020
Association Between Universal Masking in a Health Care System and SARS-CoV-2 Positivity Among Health Care Workers
(JAMA)
During the intervention period, the positivity rate decreased linearly from 14.65% to 11.46%, with a weighted mean decline of 0.49% per day and a net slope change of 1.65% (95% CI, 1.13%-2.15%; P < .001) more decline per day compared with the preintervention period.
The decrease in HCW infections could be confounded by other interventions inside and outside of the health care system (Figure), such as restrictions on elective procedures, social distancing measures, and increased masking in public spaces, which are limitations of this study.
Remember my posts about correlation vs causation? Those confounding factors listed above may be the cause of the relatively small decline with the masks being useless or even harmful. The article cited in ftnt 4 another by the NEJM as the source of its description of the universal masking that was implemented. Excerpts from that article are posted below. Unless otherwise noted, I added the bold emphasis but the language is from the article.
May 21, 2020
Universal Masking in Hospitals in the Covid-19 Era
(NEJM)
We know that wearing a mask outside health care facilities offers little, if any, protection from infection . Public health authorities define a significant exposure to Covid-19 as face-to-face contact within 6 feet with a patient with symptomatic Covid-19 that is sustained for at least a few minutes (and some say more than 10 minutes or even 30 minutes). The chance of catching Covid-19 from a passing interaction in a public space is therefore minimal. In many cases, the desire for widespread masking is a reflexive reaction to anxiety over the pandemic.
The calculus may be different, however, in health care settings. First and foremost, a mask is a core component of the personal protective equipment (PPE) clinicians need when caring for symptomatic patients with respiratory viral infections, in conjunction with gown, gloves, and eye protection. Masking in this context is already part of routine operations for most hospitals. What is less clear is whether a mask offers any further protection in health care settings in which the wearer has no direct interactions with symptomatic patients. There are two scenarios in which there may be possible benefits.
The first is during the care of a patient with unrecognized Covid-19. A mask alone in this setting will reduce risk only slightly, however, since it does not provide protection from droplets that may enter the eyes or from fomites on the patient or in the environment that providers may pick up on their hands and carry to their mucous membranes (particularly given the concern that mask wearers may have an increased tendency to touch their faces). More compelling is the possibility that wearing a mask may reduce the likelihood of transmission from asymptomatic and minimally symptomatic health care workers with Covid-19 to other providers and patients.
What is clear, however, is that universal masking alone is not a panacea. A mask will not protect providers caring for a patient with active Covid-19 if it’s not accompanied by meticulous hand hygiene, eye protection, gloves, and a gown. A mask alone will not prevent health care workers with early Covid-19 from contaminating their hands and spreading the virus to patients and colleagues. Focusing on universal masking alone may, paradoxically, lead to more transmission of Covid-19 if it diverts attention from implementing more fundamental infection-control measures.
The article concludes with what is likely one of the primary considerations in requiring the use of masks – to create a false sense of security:
It is also clear that masks serve symbolic roles. Masks are not only tools, they are also talismans that may help increase health care workers’ perceived sense of safety, well-being, and trust in their hospitals. Although such reactions may not be strictly logical, we are all subject to fear and anxiety, especially during times of crisis. One might argue that fear and anxiety are better countered with data and education than with a marginally beneficial mask, particularly in light of the worldwide mask shortage, but it is difficult to get clinicians to hear this message in the heat of the current crisis. Expanded masking protocols’ greatest contribution may be to reduce the transmission of anxiety, over and above whatever role they may play in reducing transmission of Covid-19. The potential value of universal masking in giving health care workers the confidence to absorb and implement the more foundational infection-prevention practices described above may be its greatest contribution.
So bottom line, masks are talismans of the medical and governmental shamans intended to fool us into complacency and compliance.
