1. A May 2020 meta-study on pandemic influenza published by the US CDC found that face masks had no effect, neither as personal protective equipment nor as source control.
2. A Danish randomized controlled trial with 6000 participants, published in the Annals of Internal Medicine in November 2020, found no statistically significant effect of high-quality medical face masks against SARS-CoV-2 infection in a community setting.
3. A February 2021 review by the European CDC found that there is no evidence supporting the effectiveness of non-medical and medical face masks in the community. Furthermore, the European CDC advises against the use of FFP2/N95 respirators by the general public.
4. A July 2020 review by the Oxford Centre for Evidence-Based Medicine found that there is no evidence for the effectiveness of cloth masks against virus infection or transmission.
5. A May 2020 cross-country study by the University of East Anglia (preprint) found that a mask requirement was of no benefit and could even increase the risk of infection.
6. An April 2020 review by two US professors in respiratory and infectious disease from the University of Illinois concluded that face masks have no effect in everyday life, neither as self-protection nor to protect third parties (so-called source control).
7. An article in the New England Journal of Medicine from May 2020 came to the conclusion that cloth face masks offer little to no protection in everyday life.
8. An April 2020 Cochrane review (preprint) found that face masks didn’t reduce influenza-like illness (ILI) cases, neither in the general population nor in health care workers.
9. A 2015 study in the British Medical Journal BMJ Open found that cloth masks were penetrated by 97% of particles and may increase infection risk by retaining moisture or repeated use.
10. An August 2020 review by a German professor in virology, epidemiology, and hygiene found that there is no evidence for the effectiveness of cloth face masks and that the improper daily use of masks by the public may in fact lead to an increase in infections.