WHO empfielt das Tragen von Masken in bestimmten 'settings'

Aus den guide lines der WHO zum Tragen von Masken [1].

"
Guidance on the use of masks for the general public

Available evidence

Studies of influenza, influenza-like illness, and human coronaviruses (not including COVID-19) provide evidence that the use of a medical mask can prevent the spread of infectious droplets from a symptomatic infected person (source control) to someone else and potential contamination of the environment by these droplets.(54, 55) There is limited evidence that wearing a medical mask by healthy individuals
in households, in particular those who share a house with a sick person, or among attendees of mass gatherings may be beneficial as a measure preventing transmission.(41, 56-61) A recent meta-analysis of these observational studies, with
the intrinsic biases of observational data, showed that either disposable surgical masks or reusable 12–16-layer cotton masks were associated with protection of healthy individuals within households and among contacts of cases.(42)

This could be considered to be indirect evidence for the use of masks (medical or other) by healthy individuals in the wider community; however, these studies suggest that such individuals would need to be in close proximity to an infected person in a household or at a mass gathering where physical distancing cannot be achieved, to become infected with the virus.

Results from cluster randomized controlled trials on the use of masks among young adults living in university residences in the United States of America indicate that face masks may reduce the rate of influenza-like illness, but showed no impact
on risk of laboratory-confirmed influenza.(62, 63) At present, there is no direct evidence (from studies on COVID-19 and in healthy people in the community) on the
effectiveness of universal masking of healthy people in the community to prevent infection with respiratory viruses, including COVID-19.
"

Und was empfiehlt die WHO nun aufgrund der bisherigen Studienlage?

"Advice to decision makers on the use of masks for the general public

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 (see below).

However, taking into account the available studies evaluating pre- and asymptomatic transmission, a growing compendium of observational evidence on the use of masks by the general public in several countries, individual values and preferences,
as well as the difficulty of physical distancing in many contexts, WHO has updated its guidance to advise that to prevent COVID-19 transmission effectively in areas of
community transmission, governments should encourage the general public to wear masks in specific situations and settings as part of a comprehensive approach to suppress SARS-CoV-2 transmission (Table 2)."

Was ist mit "specific situations und settings" gemeint? Auch dazu äussert sich die WHO direkt im Anschluss (Seite 6 und 7 in [1]) z.B. unter Punkt 4:

"Setting in which the population lives: settings with high population density (e.g. refugee camps, camp-like settings, those living in cramped conditions) and settings
where individuals are unable to keep a physical distance of at least 1 metre (3.3 feet) (e.g. public transportation)."

Auch in Geschäften ist es nicht immer leicht seine Distanz zu halten. Damit ist das Tragen von Masken im ÖPNV direkt von der WHO empfohlen und das Tragen von Masken in Geschäften ist naheliegend, wenn man den guide lines der WHO folgen möchte.

Ich kann nur jedem empfehlen: Glaubt nicht einfach das, was ihr in einem Forum liest! Auch dann nicht, wenn die Person einen Link zu einem Dokument angibt, welches angeblich die Behauptung beweisen soll. Lest euch den angeblichen Beweis selbst durch! Vor allem dann, wenn die Behauptung so schön eure bereits vorgefertigte Meinung stützt und es so schön wäre, wenn die Behauptung wahr wäre. Seid skeptisch und prüft nach! Fast immer, wenn ich Behauptungen derart prüfe, finde ich, dass die Behauptung nicht stimmt und die verlinkte Quelle nicht stützt, was die Person behauptet hat! Wie man z.B. hier bedauernswerter Weise wieder sehen kann [2].

[1] https://www.who.int/publications/i/item/advice-on-the-use-of-masks-in-the-community-during-home-care-and-in-healthcare-settings-in-the-context-of-the-novel-coronavirus-(2019-ncov)-outbreak
[2] https://www.heise.de/forum/Telepolis/Kommentare/Maskentragen-in-Deutschland-Der-gesunde-Menschenverstand/CDC-und-WHO-adversieren-gegen-Masken-noch-immer-egal-was-mache-Medien-versu/posting-37089348/show/