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Effectiveness of public health measures in reducing the incidence of covid-19, SARS-CoV-2 transmission, and covid-19 mortality: systematic review and meta-analysis

BMJ 2021; 375 doi: (Published 18 November 2021) Cite this as: BMJ 2021;375:e068302

Linked Editorial

Public health measures for covid-19

Rapid Response:

Misrepresenting data of peer reviewed published scientific papers by mainstream media: a potential threat for public trust in healthcare

Dear Editor,

The article by Talic et al was noticed by the main stream media (26). The article was represented with the headline “Mask wearing cuts Covid incidence by 53 % says global study” in many mainstream media all over the world (11-14), and was presented in The Guardian by the text:
“Results from more than 30 studies from around the world were analyzed in detail, showing a statistically significant 53 % reduction in the incidence of Covid with mask wearing and 25 % reduction with physical distancing. Handwashing also indicated a substantial 53% reduction in Covid incidence although this was not statistically significant after adjusting for the small number of handwashing studies.”

Moreover, the health editor Andrew Gregory writes in the same article:
"Public health on non pharmaceutical interventions are known to be beneficial in fighting respiratory tract infections like flu, and countries around the world have tried using them curb the spread of Covid."
Unfortunately both the CDC and WHO presented in their official guidelines until may-june 2020 that mask wearing by the general public to prevent viral infections like flu do not have any benefits, it could even increase infections (1,3,7,15).

Unfortunately the data of this study do not support these claims made by the journalists. The text and data of the study is different:

“Overall pooled analysis of six studies on mask wearing showed a 53 % reduction in Covid19 incidence although heterogeneity between studies was substantial. The analysis on the effects of handwashing was estimated 53% non statistically significant reduction in Covid19 incidence. Pooled data analysis of five studies indicated 25 % reduction in incidence of Covid19 by physical distancing. Heterogeneity among studies was substantial and risk of bias ranged from moderate to serious or critical for the presented analysis with a special serious-high risk on confounding (Figure 2).

"It was not possible to evaluate the impact of type of face mask (eg surgical, fabric, N95 respirators) and compliance and frequency of wearing masks owing to a lack of data. Similarly it was not feasible to assess the differences in effect that different recommendations for physical distances have as preventive strategies."

In the limitations and methodology paragraph the authors highlighted: "High quality evidence on SARS-CoV-2 and the effectiveness of public health measures is still limited with most studies having different underlying target variables. In addition the meta analytical portion of this study was limited by significant heterogeneity observed across studies, which could neither be explored nor explained by subgroup analysis or meta regression. Several studies failed to define and assess for potential confounders which made it difficult for our review to draw a one directional or causal conclusion”.

Up to now there have been no studies that allow the conclusion that wearing masks beyond any doubt can protect against infection or transmission of the virus (2,5,15,16,18,19). A report of the ECDC concluded there is no real evidence in favor of facemasks (9).

However, a number of studies suggest that masks may be harmful to human health and climate. Toxic compounds such as graphene oxide have been found in masks. In several countries (Belgium, Germany, Canada, The Netherlands) masks delivered by governments have been retracted from the market (20,21,29).

The safety of masks used by the general public cannot be guaranteed (6). A recent review concluded there is a risk of MIES (Mask Induced Exhaustion Syndrome) by longterm wearing of masks (17). Worldwide disposable masks or face shields are discarded at a rate of 3,4 billion and 1,8 billion per day respectively. People and planet health are at increasing risk, while there is no risk-benefit analysis for mask mandates available (4,8,10,22-25,27,28).

The broader remit of the BMJ is to create a healthier world. Without an ethical compass and honest information to the public, trust in doctors, scientists and public health is at risk. Talic et al. advised in their article that when implementing public health measures it is important to consider specific health and sociocultural needs of the communities and to weigh the potential negative effects of the public health measures against the positive effects for general populations. Important values for better health outcomes are social justice and equity. Ethical principles require that benefits and possible harms should be equally and truthfully presented to the public. Journalists could play an important and supportive role for an urgent transformation to a healthier world in delivering honest science based information to the public based on critical analysis.


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19. Macintyre CR, Seal H, Hung DC, Tran Hien N, Thi Nga P et al. A cluster randomized clinical trial of cloth masks compared with medical masks in healthcare workers.
20. Ministerie keurt nog eens 308 miljoen mondmaskers, brillen en schorten af. 9 november 2021.
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26. Talic S, Shah S, Wild H, Gasevic D, Maharaj A et al, Effectiveness of public health measures in reducing the incidence of covid-19, SARS-CoV-2 transmission, and covid-19 mortality: systematic review and meta analysis. BMJ 2021: 375e068302
27. Wu, X., Nethery, R. C., Sabath, M. B., Braun, D. and Dominici, F., 2020. Air pollution and COVID-19 mortality in the United States: Strengths and limitations of an ecological regression analysis. Science advances, 6(45), p.eabd4049.
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29. Winterburn T, Belgians warned not to use government distributed masks after toxic chemical scare. Euroweeklynews. 27 february 2021.

Competing interests: No competing interests

18 January 2022
Carla Peeters
Director and Founder
COBALA Good Care Feels Better, Utrecht, The Netherlands