Latest research on masking with respect to influenza & COVID prevention

[unicorn]

Here's a summary of the latest research (randomized clinical trials) from Cochrane, in studies including hundreds of thousands of people:

Cochrane Library has reviewed these studies:
https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD006207.pub6/full?highlightAbstract=covid%7Cmask

"...We included 12 trials (10 cluster‐RCTs) comparing medical/surgical masks versus no masks to prevent the spread of viral respiratory illness (two trials with healthcare workers and 10 in the community). Wearing masks in the community probably makes little or no difference to the outcome of influenza‐like illness (ILI)/COVID‐19 like illness compared to not wearing masks (risk ratio (RR) 0.95, 95% confidence interval (CI) 0.84 to 1.09; 9 trials, 276,917 participants; moderate‐certainty evidence. Wearing masks in the community probably makes little or no difference to the outcome of laboratory‐confirmed influenza/SARS‐CoV‐2 compared to not wearing masks (RR 1.01, 95% CI 0.72 to 1.42; 6 trials, 13,919 participants; moderate‐certainty evidence). Harms were rarely measured and poorly reported (very low‐certainty evidence)..."

(RCT means randomized clinical trials, the most rigorous form of scientific scrutiny)

https://www.cochrane.org/CD006207/ARI_do-physical-measures-such-hand-washing-or-wearing-masks-stop-or-slow-down-spread-respiratory-viruses

"Ten studies took place in the community, and two studies in healthcare workers. Compared with wearing no mask in the community studies only, wearing a mask may make little to no difference in how many people caught a flu-like illness/COVID-like illness (9 studies; 276,917 people); and probably makes little or no difference in how many people have flu/COVID confirmed by a laboratory test (6 studies; 13,919 people). Unwanted effects were rarely reported; discomfort was mentioned... Four studies were in healthcare workers, and one small study was in the community. Compared with wearing medical or surgical masks, wearing N95/P2 respirators probably makes little to no difference in how many people have confirmed flu (5 studies; 8407 people); and may make little to no difference in how many people catch a flu-like illness (5 studies; 8407 people), or respiratory illness (3 studies; 7799 people). Unwanted effects were not well-reported; discomfort was mentioned..."

[Riobard]

Not my take at all reading the Reynolds research team’s Cochrane-published work as well as an additional recent CoV-specific  systematic review appended here. All concede a substantial risk of bias that undermines the rigour with which a randomized control trial would be best conducted.

The few studies labelled RCT actually fall methodologically somewhere between observational and RCT because “control” in a genuine RCT does not simply denote the distinction between an intervention arm and a non-intervention control arm but aims to control, hold constant in multivariate analysis (meaning removal out of the equation via statistical techniques) those factors that can subvert or unintentionally but incorrectly support the outcome under investigation.

In contrast, a vaccine RCT narrows the exclusive effect of the inoculation. You cannot match mask-wearers and non-wearers across the many variables otherwise predictive of infection. You cannot objectively measure adherence. 

The Bangladesh geo-cluster trial reported a modest benefit. This single study doesn’t necessarily support mask wearing; risk of bias permeates both desired and non-effect results. Cherry-picking is not useful in either of two orchards geared to an a priori binary viewpoint.

My point is that there is probably no solid basis to either support or dismiss the merit of proper mask use in quantitative (ie, efficacy) terms. The pathogen has the upper hand, similarly immeasurable other than absolute incidence.

Try reading and appraising the material without predisposition one way or another to the potential benefits of a risk mitigation concept. 

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10446908/

[Riobard]

At the movies. Keeping fit, eating responsibly, staying healthy. 

Back to this subforum in a few weeks anticipating, not ruling out, the gong show some of the usual interlopers turn some of these seminars into. 

[unicorn]

On 2/18/2024 at 2:27 AM, Riobard said:

...You cannot match mask-wearers and non-wearers across the many variables otherwise predictive of infection. You cannot objectively measure adherence....

One can, and they did have observers in the RCT's. This included the Bangladeshi study, which had observers in the villages. In that study, there were other measures taken in addition to masking in the subject group, but the benefit was only 9.5%, obviously an irrelevant difference (the 95% confidence interval included no benefit). I just came back from a large medical conference in Fort Lauderdale, Florida a couple of weeks ago (Pri-Med). There were over 2000 attendees, plus staff, speakers, and exhibitors. During the whole 3-day conference, I counted 3 people wearing masks (not one of them a speaker). I took a 777-300 to and from LAX (we flew into Miami), and I saw no passengers wearing masks on the way over and two on the way back. It seems that almost everyone, especially physicians, understands the reality at this point.

Believe me, when the pandemic started, I was masked with N95's, goggles, and so on. As the studies came out, I changed my behavior on the basis of study results. I remember feeling shocked by governors who dropped mask mandates, before the studies came out. As it turned out, they guessed correctly, although it was a dangerous guess at the time. One can never, of course, prove a difference of zero. That being said, enough studies have been done, with relative risks adding up to the 0.98 to 1.02 range, that if there is a difference either way, the difference is functionally irrelevant. As much as I wish masks helped, science shows that, sadly, they do not. I know lots of people will believe in some crazy shit just because they wish it were true (look at all of those MAGA nut-heads). I'm not one of those people. 

[unicorn]

I thought about this string today while walking my dog in the park. There was actually someone who was walking outside wearing an N95. The study which essentially ruled out outdoor transmission was published in August of 2020 (if I recall correctly, they researched over 30,000 infections, and of those, about 10 may have been contracted outdoors, but in those cases, there had always been prolonged face-to-face contact such as an outdoor dining situation). It also made me think of this tour I took of southern Lake Tahoe over 30 years ago. The tour guide pointed out Liberace's mansion near the lake, which sold for a pittance because people were afraid of contracting HIV, although the fact that the disease was sexually transmitted was well-known at the time of his death in the late 80s. I guess a lot of people get solace over taking "extra precautions" even when those precautions are scientifically known to be useless. Too bad I hadn't known about the sale (and had enough money--I was in residency at the time).