Studies Showing Masks Don’t Work to Limit Spread of COVID-19, Are Harmful [Updated May 28, 2022]

Here is a running list of studies showing that masks are not effective at slowing the spread of COVID-19, or other influenza like illnesses (ILIs). This list also includes studies demonstrating the downsides of masking.

1. Annals of Internal Medicine [November 18, 2020] [RCT, lack of effectiveness]

TITLE: Effectiveness of Adding a Mask Recommendation to Other Public Health Measures to Prevent SARS-CoV-2 Infection in Danish Mask Wearers

METHODS: “DANMASK-19 (Danish Study to Assess Face Masks for the Protection Against COVID-19 Infection) was an investigator-initiated, nationwide, unblinded, randomized controlled trial ( NCT04337541). The trial protocol was registered with the Danish Data Protection Agency (P-2020-311) and published. The researchers presented the protocol to the independent regional scientific ethics committee of the Capital Region of Denmark, which did not require ethics approval (H-20023709) in accordance with Danish legislation. The trial was done in accordance with the principles of the Declaration of Helsinki.

“The sample size was determined to provide adequate power for assessment of the combined composite primary outcome in the intention-to-treat analysis. Authorities estimated an incidence of SARS-CoV-2 infection of at least 2% during the study period. Assuming that wearing a face mask halves risk for infection, we estimated that a sample of 4636 participants would provide the trial with 80% power at a significance level of 5% (2-sided α level). Anticipating 20% loss to follow-up in this community-based study, we aimed to assign at least 6000 participants.”

CONCLUSION: “A total of 3030 participants were randomly assigned to the recommendation to wear masks, and 2994 were assigned to control; 4862 completed the study. Infection with SARS-CoV-2 occurred in 42 participants recommended masks (1.8%) and 53 control participants (2.1%). The between-group difference was −0.3 percentage point (95% CI, −1.2 to 0.4 percentage point; P = 0.38) (odds ratio, 0.82 [CI, 0.54 to 1.23]; P = 0.33). Multiple imputation accounting for loss to follow-up yielded similar results. Although the difference observed was not statistically significant, the 95% CIs are compatible with a 46% reduction to a 23% increase in infection.

The recommendation to wear surgical masks to supplement other public health measures did not reduce the SARS-CoV-2 infection rate among wearers by more than 50% in a community with modest infection rates, some degree of social distancing, and uncommon general mask use. The data were compatible with lesser degrees of self-protection.

In this community-based, randomized controlled trial conducted in a setting where mask wearing was uncommon and was not among other recommended public health measures related to COVID-19, a recommendation to wear a surgical mask when outside the home among others did not reduce, at conventional levels of statistical significance, incident SARS-CoV-2 infection compared with no mask recommendation. We designed the study to detect a reduction in infection rate from 2% to 1%. Although no statistically significant difference in SARS-CoV-2 incidence was observed, the 95% CIs are compatible with a possible 46% reduction to 23% increase in infection among mask wearers. These findings do offer evidence about the degree of protection mask wearers can anticipate in a setting where others are not wearing masks and where other public health measures, including social distancing, are in effect. The findings, however, should not be used to conclude that a recommendation for everyone to wear masks in the community would not be effective in reducing SARS-CoV-2 infections, because the trial did not test the role of masks in source control of SARS-CoV-2 infection. During the study period, authorities did not recommend face mask use outside hospital settings and mask use was rare in community settings (22). This means that study participants’ exposure was overwhelmingly to persons not wearing masks.


2. Journal of Public Health Research [June 4, 2020] [side effects of masks]

TITLE: Adolescents’ face mask usage and contact transmission in novel Coronavirus

METHODS: “Both questionnaire surveys and experimental were utilized. The survey can understand the user’s thoughts and expectations, and the experiment can observe the usage behavior and contact area.

“Data for this study was obtained using a questionnaire survey of young adults aged 18-21 residing in Taiwan. University students from four different departments took part in the survey (n=160). Respondents were asked to indicate on a 5-point scale the degree to which they agreed that wearing face masks could induce problem or inconvenience (1 indicating ‘‘strongly disagree,’’ 5 indicating ‘‘strongly agree’’). High scores indicated that respondents perceived significant problems or inconvenience in wearing face masks. Five main problems of wearing face masks were listed: 1) discomfort with inhaling and exhaling, 2) excessive warmth and humidity, 3) unpleasant odor, 4) inconvenience with donning and doffing, and 5) tendency for glasses to fog up.”

CONCLUSION: “Although surgical masks are considered a viable means of protecting individuals from disease during an epidemic, accidental transmission through direct and indirect contact still puts face mask users at risk of infection. The survey of mask usage revealed the usage per day during an epidemic prevention period was 5.306 hours. Because most people repeatedly donned and doffed their masks, there was a high possibility of pollution during use. During the experiment, the subjects often had no specific place to store their masks, so they often stored the masks in their pockets, which might cause indirect contact transmission of pathogens. The average inconvenience of mask inhalation is high; and the mean value of hot and sultry is 4.025. A high degree of the agreement indicates that the smoothness of breathing is troublesome. The contact spread experiments show that the contaminated area varies considerably from user to user. The average polluted area of the ten subjects was 530 cm2. Hand contact is one of the transmission paths; when the hand touches the surface of the mask, it may spread the virus to the subsequent contact area, which is worthy of attention for general users.”


3. Influenza and Other Respiratory Viruses [February 17, 2011] [lack of effectiveness]

TITLE: Findings from a household randomized controlled trial of hand washing and face masks to reduce influenza transmission in Bangkok, Thailand

METHODS: “We studied NPIs in households with a febrile, influenza‐positive child. Households were randomized to control, hand washing (HW), or hand washing plus paper surgical face masks (HW + FM) arms. Study nurses conducted home visits within 24 hours of enrollment and on days 3, 7, and 21. Respiratory swabs and serum were collected from all household members and tested for influenza by RT‐PCR or serology.

“Between April 2008 and August 2009, 991 (16·5%) of 5995 pediatric influenza‐like illness patients tested influenza positive. Four hundred and forty‐two index children with 1147 household members were enrolled, and 221 (50·0%) were aged <6 years. Three hundred and ninety‐seven (89·8%) households reported that the index patient slept in the parents’ bedroom. The secondary attack rate was 21·5%, and 56/345 (16·3%; 95% CI 12·4–20·2%) secondary cases were asymptomatic. Hand‐washing subjects reported 4·7 washing episodes/day, compared to 4·9 times/day in the HW + FM arm and 3·9 times/day in controls (P = 0·001). The odds ratios (ORs) for secondary influenza infection were not significantly different in the HW arm (OR = 1·20; 95% CI 0·76–1·88; P‐0.442), or the HW + FM arm (OR = 1·16; 95% CI .0·74–1·82; P = 0.525).”

CONCLUSION: Influenza transmission was not reduced by interventions to promote hand washing and face mask use. This may be attributable to transmission that occurred before the intervention, poor face mask compliance, little difference in hand‐washing frequency between study groups, and shared sleeping arrangements. A prospective study design and a careful analysis of sociocultural factors could improve future NPI studies.”


4. Journal of Evidence-Based Medicine [February 9, 2021] [lack of effectiveness]

TITLE: Efficacy of surgical masks or cloth masks in the prevention of viral transmission: Systematic review, meta‐analysis, and proposal for future trial

METHODS: PubMed, EMbase, and the Cochrane Library were searched. Studies of SARS‐CoV‐2 and face masks and randomized controlled trials (RCTs) of n ≥ 50 for other respiratory illnesses were included.

CONCLUSION: “Fourteen studies were included in this study. One preclinical and 1 observational cohort clinical study found significant benefit of masks in limiting SARS‐CoV‐2 transmission. Eleven RCTs in a meta‐analysis studying other respiratory illnesses found no significant benefit of masks (±hand hygiene) for influenza‐like‐illness symptoms nor laboratory confirmed viruses. One RCT found a significant benefit of surgical masks compared with cloth masks.

There is limited available preclinical and clinical evidence for face mask benefit in SARS‐CoV‐2. RCT evidence for other respiratory viral illnesses shows no significant benefit of masks in limiting transmission but is of poor quality and not SARS‐CoV‐2 specific. There is an urgent need for evidence from randomized controlled trials to investigate the efficacy of surgical and cloth masks on transmission of SARS‐CoV‐2 and user reported outcomes such as comfort and compliance.”


5. BMJ Open [December 2016] [lack of effectiveness]

TITLE: Cluster randomised controlled trial to examine medical mask use as source control for people with respiratory illness 

METHODS: “Index cases with ILI were randomly allocated to medical mask (n=123) and control arms (n=122). Since 43 index cases in the control arm also used a mask during the study period, an as-treated post hoc analysis was performed by comparing outcomes among household members of index cases who used a mask (mask group) with household members of index cases who did not use a mask (no-mask group).

“Primary outcomes measured in household members were clinical respiratory illness, ILI and laboratory-confirmed viral respiratory infection.

In an intention-to-treat analysis, rates of clinical respiratory illness (relative risk (RR) 0.61, 95% CI 0.18 to 2.13), ILI (RR 0.32, 95% CI 0.03 to 3.13) and laboratory-confirmed viral infections (RR 0.97, 95% CI 0.06 to 15.54) were consistently lower in the mask arm compared with control, although not statistically significant. A post hoc comparison between the mask versus no-mask groups showed a protective effect against clinical respiratory illness, but not against ILI and laboratory-confirmed viral respiratory infections.”

CONCLUSION: “The study indicates a potential benefit of medical masks for source control, but is limited by small sample size and low secondary attack rates. Larger trials are needed to confirm efficacy of medical masks as source control.”


6. Clinical Infectious Diseases [August 2017] [lack of effectiveness]

TITLE: Effectiveness of Masks and Respirators Against Respiratory Infections in Healthcare Workers: A Systematic Review and Meta-Analysis 

METHODS: We conducted this systematic review and meta-analysis using a prespecified protocol (Appendix C).

We searched Pubmed, Web of Science, and EMBASE databases without language or time restrictions for articles satisfying the following criteria:

CONCLUSION: “In this review and meta-analysis, we analysed the collective evidence from published RCTs and observational studies in order to identify major gaps and methodological shortcomings in the current literature and develop evidence-based recommendations for the use of masks and respirators in healthcare settings. We found evidence to support universal medical mask use in hospital settings as part of infection control measures to reduce the risk of CRI and ILI among HCWs. Overall, N95 respirators may convey greater protection, but universal use throughout a work shift is likely to be less acceptable due to greater discomfort.

“Our analysis confirms the effectiveness of medical masks and respirators against SARS. Disposable, cotton, or paper masks are not recommended.

“The confirmed effectiveness of medical masks is crucially important for lower-resource and emergency settings lacking access to N95 respirators. In such cases, single-use medical masks are preferable to cloth masks, for which there is no evidence of protection and which might facilitate transmission of pathogens when used repeatedly without adequate sterilization.


7. PLOS ONE [January 25, 2012] [lack of effectiveness]

TITLE: Facemasks, Hand Hygiene, and Influenza among Young Adults: A Randomized Intervention Trial

METHODS: “A cluster-randomized intervention trial (Mflu) was conducted at the University of Michigan (trial registration: Intervention Study of Face Mask and Hand Sanitizer to Reduce Influenza Transmission (M-FLU), Identifier: NCT00490633. Findings from the first year of Mflu for the 2006–2007 flu season have been published. The 2007–2008 trial described here followed 1,178 young adults living within university residence halls during the influenza season and included a significantly larger number of clusters for randomization. Thirty-seven residence houses located in five residence halls were randomly assigned to either an intervention or a control group. Students living in these residence halls were eligible for the study if they were at least 18 years of age, willing to wear a face mask, use alcohol-based hand sanitizer, provide a throat swab specimen when sick, and complete one baseline and six weekly on-line surveys. Students reporting an allergy to alcohol-based hand sanitizer were excluded. Based on data from year one of the Mflu study and assuming an 8% observable ILI attack rate in the control group, we had 87% power to detect a reduction of 25% (i.e. a rate ratio [RR] = 0.75) or greater in illness rates between intervention and control groups at an α-level 0.05, using the methods of Hayes et al for cluster randomized trials. The CONSORT checklist is presented in Checklist S1.”

CONCLUSION: “A significant reduction in the rate of ILI was observed in weeks 3 through 6 of the study, with a maximum reduction of 75% during the final study week (rate ratio [RR] = 0.25, [95% CI, 0.07 to 0.87]). Both intervention groups compared to the control showed cumulative reductions in rates of influenza over the study period, although results did not reach statistical significance. Generalizability limited to similar settings and age groups. Face masks and hand hygiene combined may reduce the rate of ILI and confirmed influenza in community settings. These non-pharmaceutical measures should be recommended in crowded settings at the start of an influenza pandemic.”

“Our study demonstrated a significant association between the combined use of face masks and hand hygiene and a substantially reduced incidence of ILI during a seasonal influenza outbreak. If masks and hand hygiene have similar impacts on primary incidence of infection with other seasonal and pandemic strains, particularly in crowded, community settings, then transmission of viruses between persons may be significantly decreased by these interventions. Masks alone did not provide a benefit, suggesting that single personal protective interventions do not protect against incidence of ILI or influenza. However, it is possible that either lack of power to detect small effects from mask use alone or that the amount of time masks were worn was not sufficient alone to provide a reduction in illness. Our timely findings regarding the efficacy of masks and hand hygiene highlight the significance of examining their impact on influenza infection within community settings.”


8. Acta Neurologica Scandinavia [January 25, 2006] [lack of effectiveness]

TITLE: Headaches and the N95 face‐mask amongst healthcare providers

METHODS: “We administered a survey to healthcare workers to determine risk factors associated with development of headaches (frequency, headache subtypes and duration of face‐mask wear) and the impact of headaches (sick days, headache frequency and use of abortive/preventive headache medications).”

CONCLUSION: Healthcare providers may develop headaches following the use of the N95 face‐mask. Shorter duration of face‐mask wear may reduce the frequency and severity of these headaches.”


9. Emerging Infectious Diseases [May 2020] [lack of effectiveness]

TITLE: Nonpharmaceutical Measures for Pandemic Influenza in Nonhealthcare Settings—Personal Protective and Environmental Measures

METHODS: “We conducted systematic reviews to evaluate the effectiveness of personal protective measures on influenza virus transmission, including hand hygiene, respiratory etiquette, and face masks, and a systematic review of surface and object cleaning as an environmental measure (Table 1). We searched 4 databases (Medline, PubMed, EMBASE, and CENTRAL) for literature in all languages. We aimed to identify randomized controlled trials (RCTs) of each measure for laboratory-confirmed influenza outcomes for each of the measures because RCTs provide the highest quality of evidence. For respiratory etiquette and surface and object cleaning, because of a lack of RCTs for laboratory-confirmed influenza, we also searched for RCTs reporting effects of these interventions on influenza-like illness (ILI) and respiratory illness outcomes and then for observational studies on laboratory-confirmed influenza, ILI, and respiratory illness outcomes. For each review, 2 authors (E.Y.C.S. and J.X.) screened titles and abstracts and reviewed full texts independently.

“We performed meta-analysis for hand hygiene and face mask interventions and estimated the effect of these measures on laboratory-confirmed influenza prevention by risk ratios (RRs). We used a fixed-effects model to estimate the overall effect in a pooled analysis or subgroup analysis. No overall effect would be generated if there was considerable heterogeneity on the basis of I2 statistic >75% (6). We performed quality assessment of evidence on hand hygiene and face mask interventions by using the GRADE (Grading of Recommendations Assessment, Development and Evaluation) approach (7). We provide additional details of the search strategies, selection of articles, summaries of the selected articles, and quality assessment (Appendix).”

CONCLUSION: “There were 3 influenza pandemics in the 20th century, and there has been 1 so far in the 21st century. Local, national, and international health authorities regularly update their plans for mitigating the next influenza pandemic in light of the latest available evidence on the effectiveness of various control measures in reducing transmission. Here, we review the evidence base on the effectiveness of nonpharmaceutical personal protective measures and environmental hygiene measures in nonhealthcare settings and discuss their potential inclusion in pandemic plans. Although mechanistic studies support the potential effect of hand hygiene or face masks, evidence from 14 randomized controlled trials of these measures did not support a substantial effect on transmission of laboratory-confirmed influenza. We similarly found limited evidence on the effectiveness of improved hygiene and environmental cleaning. We identified several major knowledge gaps requiring further research, most fundamentally an improved characterization of the modes of person-to-person transmission.

“In our systematic review, we identified 10 RCTs that reported estimates of the effectiveness of face masks in reducing laboratory-confirmed influenza virus infections in the community from literature published during 1946–July 27, 2018. In pooled analysis, we found no significant reduction in influenza transmission with the use of face masks (RR 0.78, 95% CI 0.51–1.20; I2 = 30%, p = 0.25) (Figure 2). One study evaluated the use of masks among pilgrims from Australia during the Hajj pilgrimage and reported no major difference in the risk for laboratory-confirmed influenza virus infection in the control or mask group (33). Two studies in university settings assessed the effectiveness of face masks for primary protection by monitoring the incidence of laboratory-confirmed influenza among student hall residents for 5 months (9,10). The overall reduction in ILI or laboratory-confirmed influenza cases in the face mask group was not significant in either studies (9,10). Study designs in the 7 household studies were slightly different: 1 study provided face masks and P2 respirators for household contacts only (34), another study evaluated face mask use as a source control for infected persons only (35), and the remaining studies provided masks for the infected persons as well as their close contacts. None of the household studies reported a significant reduction in secondary laboratory-confirmed influenza virus infections in the face mask group (1113,15,17,34,35). Most studies were underpowered because of limited sample size, and some studies also reported suboptimal adherence in the face mask group.

“Disposable medical masks (also known as surgical masks) are loose-fitting devices that were designed to be worn by medical personnel to protect accidental contamination of patient wounds, and to protect the wearer against splashes or sprays of bodily fluids (36). There is limited evidence for their effectiveness in preventing influenza virus transmission either when worn by the infected person for source control or when worn by uninfected persons to reduce exposure. Our systematic review found no significant effect of face masks on transmission of laboratory-confirmed influenza.


10. PLoS One [May 2008] [lack of effectiveness]

TITLE: Preliminary findings of a randomized trial of non-pharmaceutical interventions to prevent influenza transmission in households

METHODS: “There are sparse data on whether non-pharmaceutical interventions can reduce the spread of influenza. We implemented a study of the feasibility and efficacy of face masks and hand hygiene to reduce influenza transmission among Hong Kong household members.

“We conducted a cluster randomized controlled trial of households (composed of at least 3 members) where an index subject presented with influenza-like-illness of <48 hours duration. After influenza was confirmed in an index case by the QuickVue Influenza A+B rapid test, the household of the index subject was randomized to 1) control or 2) surgical face masks or 3) hand hygiene. Households were visited within 36 hours, and 3, 6 and 9 days later. Nose and throat swabs were collected from index subjects and all household contacts at each home visit and tested by viral culture. The primary outcome measure was laboratory culture confirmed influenza in a household contact; the secondary outcome was clinically diagnosed influenza (by self-reported symptoms). We randomized 198 households and completed follow up home visits in 128; the index cases in 122 of those households had laboratory-confirmed influenza. There were 21 household contacts with laboratory confirmed influenza corresponding to a secondary attack ratio of 6%. Clinical secondary attack ratios varied from 5% to 18% depending on case definitions. The laboratory-based or clinical secondary attack ratios did not significantly differ across the intervention arms. Adherence to interventions was variable.

CONCLUSION: “The secondary attack ratios were lower than anticipated, and lower than reported in other countries, perhaps due to differing patterns of susceptibility, lack of significant antigenic drift in circulating influenza virus strains recently, and/or issues related to the symptomatic recruitment design. Lessons learnt from this pilot have informed changes for the main study in 2008.”


11. International Journal of Infection Control [1996] [lack of effectiveness]

TITLE: Use of cloth masks in the practice of infection
control – evidence and policy gaps

METHODS: “Cloth masks are commonly used in low and middle income countries. It is generally believed that the primary purpose of cloth masks is to prevent spread of infections from the wearer. However, historical evidence shows that they have previously been used to protect health care workers (HCWs) from respiratory infections. Currently there is a lack of evidence on the efficacy of cloth masks. In this paper, we examined the evidence around the efficacy of cloth masks and discuss the use of cloth masks as a mode of protection from infections in HCWs. We also reviewed the various approaches implemented to try and improve the effectiveness of cloth masks; for example; type of fabric, masks design and face fit.”

CONCLUSION:Although cloth masks are commonly used in low/
middle income countries, there is minimal policy acknowledgment of the need for cloth masks, and a lack of evidence on their efficacy and use. Cloth masks are generally not mentioned in any policies on the use of PPE during an influenza pandemic. The lack of recommendations for respiratory protection may be due to a lack of evidence on their efficacy. Despite the lack of evidence and the little attention paid to cloth masks in guidelines and policies, they continue to be widely used around the world, particularly in resource-poor countries
In many settings, the high cost of masks and respirators (around $0.14USD per surgical mask and $0.63USD per N95 respirator for products manufactured by a leading company) is probably one of the main factors inhibiting the regular use of these products. More concerning is the fact that cloth masks are widely used in countries which have been historically important for the emergence of new infections such as China and Vietnam. There is an urgent need for research to quantify the efficacy of cloth masks with a RCT, and to study the various associated practices such as re-use and sterilization techniques globally. Future research questions could focus on clinical efficacy, filtration efficacy, length of use, methods of decontamination and fit testing. The use of cloth masks should be addressed in policy documents to inform current practice in low and middle income countries.”


12. Clinical Infectious Diseases [August 31, 2000] [lack of effectiveness]

TITLE: Nosocomial respiratory syncytial virus infections: the “Cold War” has not ended

ABSTRACT: “Respiratory syncytial virus (RSV) is a major nosocomial hazard on pediatric wards during its annual outbreaks. It produces significant morbidity in young children and is most severe in those with underlying conditions, especially cardiopulmonary and immunosuppressive diseases. In older patients, RSV may exacerbate an underlying condition or pulmonary and cardiac manifestations. On transplant units, of RSV may be occult and is associated with high mortality rates. The manifestations of nosocomial RSV infections may be atypical, especially in neonates and immunosuppressed patients, resulting in delayed or missed diagnosis and adding appreciably to the costs of hospitalization. RSV is primarily spread by close contact with infectious secretions, either by large-particle aerosols or by fomites and subsequent self-inoculation, and medical staff are often instrumental in its transmission. Thus, integral to any infection control program is the education of personnel about the modes of transmission, the manifestations, and the importance of RSV nosocomial infections. Hand washing is probably the most important infection control procedure. The choice of barrier controls should be decided by individual institutions depending on the patients, the type of ward, and the benefit relative to cost.”

CONCLUSION: It has not been clearly shown that wearing masks has any additional benefit. Most studies use of masks do so as part of multiple infection control procedures, not allowing delineation of any additional possible benefit from masks alone. However, masks without eye protection may offer only limited protection, given that the eyes are also effective portals of inoculation for RSV. Therefore masks, if appropriately used, may act as a barrier for 1 of the 2 most effective sites for inoculation of RSV. The use of eye-nose goggles has been shown to be beneficial [32]. Their use, however, may be limited by acceptability and additional expense, and much of their benefit could probably be achieved by strict hand washing.”


13. American Journal of Infection Control [June 2009] [lack of effectiveness]

TITLE: Use of surgical face masks to reduce the incidence of the common cold among health care workers in Japan: A randomized controlled trial

METHODS: Health care workers in a tertiary care hospital in Japan were randomized into 2 groups: 1 that wore face masks and 1 that did not. They provided information about demographics, health habits, and quality of life. Participants recorded symptoms daily for 77 consecutive days, starting in January 2008. Presence of a cold was determined based on a previously validated measure of self-reported symptoms. The number of colds between groups was compared, as were risk factors for experiencing cold symptoms.

CONCLUSION: Face mask use in health care workers has not been demonstrated to provide benefit in terms of cold symptoms or getting colds. A larger study is needed to definitively establish noninferiority of no mask use.


14. Environmental Research and Public Health [2020] [side effects]

TITLE: Subjective Deterioration of Physical and Psychological Health during the COVID-19 Pandemic in Taiwan: Their Association with the Adoption of Protective Behaviors and Mental Health Problems

METHODS: “The current investigation was based on the dataset of the Survey of Health Behaviors During the COVID-19 Pandemic in Taiwan, which was comprehensively described elsewhere [34]. Briefly, a Facebook advertisement was deployed between 10 April 2020 and 23 April 2020. We targeted the advertisement to Facebook users by location (Taiwan) and language (Chinese), where Facebook’s advertising algorithm determined which users to show our advertisement to. Facebook users who were 20 years or older and resided in Taiwan were eligible for this study. Participants reached the research questionnaire website through the Facebook advertisement, which was composed of a headline, main text, pop-up banner, and weblink. A total of 2031 respondents completed the research questionnaire; of them, 77 respondents were excluded due to missing data on any variable or being younger than 20. Data from 1954 respondents were analyzed. Figure 1 demonstrates the flowchart of study design. The Institutional Review Board (IRB) of Kaohsiung Medical University Hospital that is responsible for ethical review approved this study (KMUHIRB-EXEMPT(I) 20200011). As participation was voluntary and survey responses were anonymous, written informed consent was waived based on the approval of IRB. The participants were given no incentive for participation. We provided links to Taiwan Centers for Disease Control, Kaohsiung Medical University Hospital, and Medical College of National Cheng Kung University for participants to learn more about COVID-19 at the end of the online questionnaire. The analyses of information sources [34], sexual behaviors [35], and sleep and suicidality [36] using the dataset have been published elsewhere.”

CONCLUSION: “This Facebook-based online study on the general public in Taiwan found that 13.2% and 19.3% of respondents reported deteriorated physical and psychological health during the COVID-19 pandemic, respectively. Both subjective deteriorations of physical and psychological health positively related to general anxiety. The results indicate that the physical and psychological health of the public, but not only those who were contracted with COVID-19, should be focus of health professionals’ concern. The present study identified several health belief constructs, social support and demographic characteristics that were significantly associated with deteriorated physical and psychological health. These factors can be used to screen for the individuals who need intervention for physical and psychological health problems. The subjective deterioration of psychological health was significantly associated with avoiding crowded places and wearing a mask. Further study is needed to examine the mechanism accounting for the association and provide reference for developing strategies to promote adoption of protective behaviors against respiratory infectious diseases.”


15. La Revue des Maladies Respiratoires [March 2018] [side effects]

TITLE: Effect of a surgical mask on six minute walking distance

METHODS: “It is a prospective study on 44 healthy subjects. After a first 6MWT for training, they performed randomly two 6MWT: with or without a surgical mask. Distance and dyspnea, heart rate and saturation variations were recorded.”

CONCLUSION: “Distance was not modified by the mask (P=0.99). Dyspnea [labored breathing – SRN] variation was significantly higher with surgical mask (+5.6 vs. +4.6; P<0.001) and the difference was clinically relevant. No difference was found for the variation of other parameters.

“Wearing a surgical mask modifies significantly and clinically dyspnea without influencing walked distance.”


16. International Archives of Occupational and Environmental Health [May 26, 2005] [side effects]

TITLE: Effects of wearing N95 and surgical facemasks on heart rate, thermal stress and subjective sensations

METHODS: Ten healthy subjects, five men and five women, participated in the study, and their physical characteristics are summarized in Table 1. None was a smoker. Female subjects participated in the experiment only when they were during follicular phases.

CONCLUSION: The results from the experiment demonstrate that heart rate, microclimate (temperature, humidity) and subjective ratings were significantly influenced by the wearing of different kinds of facemasks. Nielsen et al. (1987) observed that delivery of air with different temperatures into a facemask corresponded to the application of a local thermal stimulus to the skin surface around the mouth, nose and cheek. This local thermal stimulus also affected the heat exchange from the respiratory tract. In our investigation, microclimate temperature, humidity and skin temperature inside the facemask increased with the start of step exercise, which led to the different perceptions of humidity, heat and high breathing resistance among the subjects wearing the facemasks. High breathing resistance made it difficult for the subject to breathe and take in sufficient oxygen. Shortage of oxygen stimulates the sympathetic nervous system and increases heart rate (Ganong 1997). It was probable that the subjects felt unfit, fatigued and overall discomfort due to this reason. White et al. (1991) found that the increases in heart rate, skin temperature and subjective ratings may pose substantial additional stress to the wearer and might reduce work tolerance. This could be the reason why Farquharson reported that working 12-h shifts while wearing an N95 mask had indeed been a challenge to their ED staff (Farquharson and Baguley 2003).

Therefore, it can be concluded that N95 and surgical facemasks can induce significantly different temperatures and humidity in the microclimates of facemasks, which have profound influences on heart rate and thermal stress and subjective perception of discomfort.


17. Clinical Research in Cardiology volume [DISCOMFORT] [July 6, 2020]

TITLE: Effects of surgical and FFP2/N95 face masks on cardiopulmonary exercise capacity

METHODS: This prospective cross-over study quantitated the effects of wearing no mask (nm), a surgical mask (sm) and a FFP2/N95 mask (ffpm) in 12 healthy males (age 38.1 ± 6.2 years, BMI 24.5 ± 2.0 kg/m2). The 36 tests were performed in randomized order. The cardiopulmonary and metabolic responses were monitored by ergo-spirometry and impedance cardiography. Ten domains of comfort/discomfort of wearing a mask were assessed by questionnaire.

CONCLUSION: Ventilation, cardiopulmonary exercise capacity and comfort are reduced by surgical masks and highly impaired by FFP2/N95 face masks in healthy individuals. These data are important for recommendations on wearing face masks at work or during physical exercise.


18. International Research Journal of Public Health [2021] [lack of effectiveness]

TITLE: Mask mandate and use efficacy for COVID-19 containment in US States

METHODS: We calculated total COVID-19 case growth and mask use for the continental United States with data from the Centers for Disease Control and Prevention and Institute for Health Metrics and Evaluation. We estimated post-mask mandate case growth in non-mandate states using median issuance dates of neighboring states with mandates.

CONCLUSION: Earlier mask mandates were not associated with lower total cases or lower maximum growth rates. Earlier mandates were weakly associated with lower minimum COVID-19 growth rates. Mask use predicted lower minimum but not lower maximum growth rates. Growth rates and total growth were comparable between US states in the first and last mask use quintiles during the Fall-Winter wave. These observations persisted for both natural logarithmic and fold growth models and when adjusting for differences in US state population density.

We did not observe association between mask mandates or use and reduced COVID-19 spread in US states. COVID-19 mitigation requires further research and use of existing efficacious strategies, most notably vaccination.


19. Souther Medical Journal [September 3, 2021]

TITLE: Analysis of the Effects of COVID-19 Mask Mandates on Hospital Resource Consumption and Mortality at the County Level

METHODS: We used publicly reported county-level data to perform a mixed-methods before-and-after analysis along with other sources of public data for analyses of covariance. We used a least-squares regression analysis to adjust for confounders. A Texas state-level mask order was issued on July 3, 2020, followed by a Bexar County–level order on July 15, 2020. We defined the control period as June 2 to July 2 and the postmask order period as July 8, 2020–August 12, 2020, with a 5-day gap to account for the median incubation period for cases; longer periods of 7 and 10 days were used for hospitalization and ICU admission/death, respectively. Data are reported on a per-100,000 population basis using respective US Census Bureau–reported populations.

CONCLUSION: From June 2, 2020 through August 12, 2020, there were 40,771 reported cases of COVID-19 within Bexar County, with 470 total deaths. The average number of new cases per day within the county was 565.4 (95% confidence interval [CI] 394.6–736.2). The average number of positive hospitalized patients was 754.1 (95% CI 657.2–851.0), in the ICU was 273.1 (95% CI 238.2–308.0), and on a ventilator was 170.5 (95% CI 146.4–194.6). The average deaths per day was 6.5 (95% CI 4.4–8.6). All of the measured outcomes were higher on average in the postmask period as were covariables included in the adjusted model. When adjusting for traffic activity, total statewide caseload, public health complaints, and mean temperature, the daily caseload, hospital bed occupancy, ICU bed occupancy, ventilator occupancy, and daily mortality remained higher in the postmask period.

There was no reduction in per-population daily mortality, hospital bed, ICU bed, or ventilator occupancy of COVID-19-positive patients attributable to the implementation of a mask-wearing mandate.


20. Agency: Deutsche Gesellschaft für Pädiatrische Infektiologie [December 19, 2020]

TITLE: Corona children studies “Co-Ki”: First results of a Germany-wide registry on mouth and nose covering (mask) in children

METHODS: “At the University of Witten/Herdecke an online registry has been set up where parents, doctors, pedagogues and others can enter their observations. On 20.10.2020, 363 doctors were asked to make entries and to make parents and teachers aware of the registry.”

CONCLUSION: “By 26.10.2020 the registry had been used by 20,353 people. In this publication we report the results from the parents, who entered data on a total of 25,930 children. The average wearing time of the mask was 270 minutes per day.  Impairments caused by wearing the mask were reported by 68% of the parents. These included irritability (60%)headache (53%)difficulty concentrating (50%)less happiness (49%)reluctance to go to school/kindergarten (44%)malaise (42%) impaired learning (38%) and drowsiness or fatigue (37%).”


21. Preprint in The Lancet (May 25, 2022)

TITLE: Revisiting Pediatric Covid-19 cases in Counties With and Without School Mask Requirements—
United States, July 1—October 20 2021.

METHODS: “Our study replicates a highly cited CDC study showing a negative association
between school mask mandates and pediatric SARS-CoV-2 cases. We then extend the study
using a larger sample of districts and a longer time interval, employing almost six times as
much data as the original study. We examine the relationship between mask mandates and
per-capita pediatric cases, using multiple regression to control for differences across school

CONCLUSION: “Replicating the CDC study shows similar results; however, incorporating a larger
sample and longer period showed no significant relationship between mask mandates and
case rates. These results persisted when using regression methods to control for differences
across districts.”

“School districts that choose to mandate masks are likely to be systematically
different from those that do not in multiple, often unobserved, ways. We failed to establish a
relationship between school masking and pediatric cases using the same methods but a
larger, more nationally diverse population over a longer interval.
Our study demonstrates
that observational studies of interventions with small to moderate effect sizes are prone to
bias caused by selection and omitted variables. Randomized studies can more reliably inform
public health policy.”


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