tisdag 24 november 2020

The media fiasco over the Danish face mask study

The media coverage of the Danish face mask study whose results were announced last week has been deeply misleading, as I explain in my second blog post1 at the International Statistical Institute's Statisticians React to the News. Here is how it begins:
    The Swedish approach to the covid-19 crisis stands out compared to the rest of the developed world in several ways. One of these is the extremely low percentage of the population wearing face masks.

    This behavior has been consistently egged on by the Public Health Agency of Sweden (FHM), who throughout the pandemic have refused to recommend the use of face masks other than in medical care. This puts them at odds with the WHO and with the global scientific community at large. There is some opposition to FHM's policy also in Sweden, but I doubt that even the report last week from the Nobel Prize awarding Royal Swedish Academy of Sciences (recommending the use of face masks) will have any effect on the FHM.

    Due to the lack of transparent decision making at FHM, it remains unclear exactly why they take their unusual stance on face masks, although in my previous blog post at Statisticians React to the News I offered some speculations. When the Swedish news channel TV4 requested the scientific basis for their stance, the FHM offered a list of 37 scientific articles, and when TV4 went on to ask British expert Melinda Mills to go over it she found that the set of articles pointed overwhelmingly in the direction of face masks having a substantial effect. Astonishingly, in a recent press conference, Karin Tegmark Wisell at the FHM hinted at a fairness aspect: a face mask recommendation would induce costs that would be felt more strongly by low-income households.

    Be all that as it may, the results of a Danish study (published in the Annals of Internal Medicine) on the effects of wearing a face mask were announced last week. Given the news coverage it received, it is likely to feed into and reinforce the negative attitude towards face masks that dominates in Sweden.

Read the rest of the piece here.


1) The first one was published in August: On science, uncertainty, the atomic bomb, and covid-19.

5 kommentarer:

  1. Also interesting that the control group had 5 PCR infections while the mask group had 0. Remaining infections were determined from antibody tests with high error rates. Read more from Nassim Taleb here: https://fooledbyrandomnessdotcom.wordpress.com/2020/11/25/hypothesis-testing-in-the-presence-of-false-positives-the-flaws-in-the-danish-mask-study/

  2. Is it really so clear that scientific evidence 'points overwhelmingly in the direction of face masks having a substantial effect', without any further qualifications?
    In their report from June 5 2020, the Who writes:

    'Many countries have recommended the use of fabric masks/face coverings for the general public. At the present time, the widespread use of masks by healthy people in the community setting is not yet supported by high quality or direct scientific evidence and there are potential benefits and harms to consider'.

    The Who also says that governments nevertheless should recommend the use of masks in specific situations, but lists several potentially negative effects of face masks, most of which are familiar from FHM's recommendations.

    There is a danger in presenting the attitude of the FHM in the way you do; as completely unreasonable. It is not, and if you don't understand the arguments of your opponent, there is little chance of making progress.

    Bo Berndtsson

    1. Whaddayamean "without any further qualifications"? If you go back and read more carefully, you'll find that the "pointed overwhelmingly" passage refers not to scientific evidence in general, but to the specific set of 37 articles that the FHM holds forth as the scientific basis for their stance on face masks.

    2. Eh? I haven't read the 37 articles, but

      a. if I read even more carefully it points, not to the 37 articles, but to the interpretation of them by Melinda M. Why is that more reliable than the interpretation of FHM?

      b. if you really think that 'it remains unclear exactly why they [FHM] take their unusual stance on face masks' you should read the Who documents. The one I quoted, from June 5, is an 'update' of a similar document from April 6. This April document lists recommended measures, of which the wide spread use of face masks is not one:

      "Medical masks should be reserved for health care workers.The use of medical masks in the community may create a false sense of security, with neglect of other essential measures, such as hand hygiene practices and physical distancing, and may lead to touching the face under the masks and under the eyes, result in unnecessary costs, and take masks away from those in health care who need them most".

      Is it not rather clear on what the FHM bases its recommendations?

      c. My 'without further qualifications' means the following. Everybody agrees that face masks should be worn in some situations; the question is in which. On this I have no opinion and no expert knowledge. What I object to is the all to common description of the FHM as unreasonable, idiotic and driven only by prestige.


    3. You may object and quote-mine all you like, but the fact remains that to a rational eye, FHM's stance on face masks comes across as highly unreasonable. To what extent prestige is a factor here I really do not know, and I cannot recall having speculated in public about it, so why you bring it up here is a bit of a mystery to me.