> "They continue not to wear masks," he said. "That can be a big drawback in the Swedish strategy if masks prove effective and key in fighting the pandemic."
There aren't any randomized trials that look at cloth masks. There is one trial enrolling in Guinea Bissau. It seems likely we may never know because there isn't an interest in doing trials.
This article from Oxford's Centre for Evidence-Based Medicine discusses the issues with masks:
The current working hypothesis seems to be that wearing a mask protects other people from getting infected by the wearer, rather than the wearer himself. Testing this hypothesis in a randomized control trial sounds extremely difficult, since it is usually not known who infected whom. On the other hand, masks are basically free and reducing the amount of saliva we spit at each other sounds like a resonable measure during a pandemic.
I agree It's difficult to experimentally test using an RTC. Unfortunately the attitude you mention also results (in my observations) in undermining the trustworthiness of the CDC/Government (in the US) for many people who see there is no real data for it, nor do they really see cause effect. It reinforces "pop science" for media outlets. People see ineffective rules such as "wearing a mask walking to a table, but not at the table while dinning" and realize it's not consistent and result in many not trusting other policies that may actually be helfpul.
Extrapolating from small studies of reducing particles to being an effective countermeasure is a big unsubstantiated leap and may result in unintended consequences (e.g. say less healthy people exposed and gaining partial immunity during summer months that). Perhaps it's somewhat effective, but the big problem to me is undermining the credibility of the scientific process and institutions. In the future, it also may lead to less research on truly effective methods as many people (and governments) assume social distancing and masks are effective without backing data and research.
For example of research suggesting lack of effectiviness of masks and social distancing as anti-pandemic methods, there's a research article on my reading queue that by using a non-heterogeneous infection susceptibility over the classic very simplified SIR model shows that the number of US infections is essentially what would be expected of a natural infection based on current parameter estimations [1]. There are several other points of data indicating similar lack of effectiveness, form the considering raw graphs and timelines, to the much lower "soft-immunity" numbers of ~10-25% of the population, to Sweden's numbers being 15x lower than predicted by standard SIR models. I'd list more data but my lunch is over, and if you're interested it's not too difficult to find. There's a lot of research that is needed in other words, not "pop science" which is hard. Giving in to easy answers is an emotional palliative but not a good societal strategy in my mind. To quote the Royal Societies motto: " Nullius in verba".
From the linked preprint:
> Allowing for heterogeneity reduces the estimate of "counterfactual" deaths that would have occurred if there had been no interventions from 3.2 million to 262,000, implying that most of the slowing and reversal of COVID-19 mortality is explained by the build-up of herd immunity. The estimate of the herd immunity threshold depends on the value specified for the infection fatality ratio (IFR): a value of 0.3% for the IFR gives 15% for the average herd immunity threshold.
This is not the point I was trying to make. Of course it is important to monitor new scientific evidence that arises and to update the measures and recommendations accordingly. I believe that most functional governments are trying to do exactly that in the current situation.
The issue is that politicians usually don't have the luxury of having lots of high-quality studies available. At the same time, it is impossible not to communicate. Not recommending masks sends the message "masks don't work", for which there is not much evidence either. Unlike scientists, politicians constantly have to make best guesses using the limited information that is available to them.
There is also the question as to whether people can safely use masks without infecting themselves. If masks help at the margin they can also hurt at the margin. They can also cause the public to neglect physical distancing and hand washing based on a false sense of security.
It's puzzling why many have assumed a positive or neutral effect for something so untested. It's clear physical distancing has had the most effect as evidenced by Google mobility reports.
The idea that people might infect themselves by handling their own masks sounds very far-fetched to me. What mechanism is supposed to do that?
The risk of people neglecting other measures sounds more reasonable, but most politicians seem to believe that the positive effect of not spitting at each other wins. Again, they have to make educated guesses based on the limited information that is available.
I don't think one can conclude from mobility reports being somehow correlated with infection numbers that physical distancing has had the most effect. Human behavior is much more complicated than that and one surely needs a more complex model.
> The idea that people might infect themselves by handling their own masks sounds very far-fetched to me. What mechanism is supposed to do that?
The article I linked discusses the only study on cloth masks from 2015. The study has some limitations but showed that cloth masks had a higher rate of infection.
In the general population it's not hard to imagine compliance will not be perfect. That is why we need controlled trials.
There have also been assumptions that homeopathy doesn't harm. Scientists did a survey and discovered that therapists were recommending that their patients didn't vaccinate. This is from the book Trick or Treatment.
TLDR: Testing assumptions is very important. Lives depend on it.
> TLDR: Testing assumptions is very important. Lives depend on it.
100% this! Masks are one of those "obvious" things. But scientific inquiry has repeatedly shown we need to test obvious things. Preferably before making legally binding policies.
There aren't any randomized trials that look at cloth masks. There is one trial enrolling in Guinea Bissau. It seems likely we may never know because there isn't an interest in doing trials.
This article from Oxford's Centre for Evidence-Based Medicine discusses the issues with masks:
https://www.cebm.net/covid-19/masking-lack-of-evidence-with-...