Prevalence and Factors Associated with the Reuse of Mask during the COVID-19 Pandemic: A Nationwide Survey in Taiwan

Mask usage is an effective measure to prevent severe acute respiratory syndrome coronavirus 2 (SARS-COV-2) infection; however, mask reuse is not recommended. Studies examining the factors associated with mask reuse during the coronavirus disease (COVID-19) pandemic are limited. This nationwide survey aimed to determine the prevalence and factors associated with mask reuse among Taiwanese citizens during the pandemic. From 18 May through 31 May 2020, a computer-assisted telephone interview system was used to randomly select Taiwanese citizens for interview regarding COVID-19-preventive behaviors and knowledge on mask usage. For a total of 1075 participants, the overall mean age was 57.4 years, and 82.2% of participants reported mask reuse during the COVID-19 pandemic. After controlling for other covariates, participants who had a greater knowledge of mask usage or had a high supply of masks were less likely to reuse masks during the pandemic. Moreover, generalized estimating equations (GEE) analysis showed that, compared with the participants’ mask-wearing behaviors before the COVID-19 pandemic, they were more likely to reuse masks during the pandemic. Thus, it is imperative to educate people on the correct usage of masks. Furthermore, the government should provide sufficient masks to the general population to reduce mask reuse.


Introduction
Coronavirus disease  is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and it was first detected in Wuhan, China, in December 2019. COVID-19 transmission has rapidly accelerated, resulting in it becoming a pandemic within a short period [1], and as of 12 July 2021, more than 186.4 million individuals have been infected with COVID-19 globally, with the official death toll reaching 4.0 million [2].

COVID-19 Prevention
As the number of COVID-19 patients continues to increase, data increasingly show that not only do medical staff in hospitals require face masks as personal protective equip-ment [3], but the effective reproduction number (R0) can also be decreased below 1 when face masks are continuously used by the general public, mitigating the spread of the pandemic [4]. To prevent the COVID-19 outbreak, Taiwan Centers for Disease Control (CDC) has implemented several strategies, including public use of masks, border control, and quarantine procedures since early January 2020 [5][6][7]. By 12 July 2021, 15,273 laboratoryconfirmed COVID-19 cases were reported by Taiwan CDC, including 1284 (8.4%) in those entering Taiwan [8]. The national mortality rate in laboratory-confirmed COVID-19 cases was 4.9% [8].
COVID-19-prevention measures include pharmacological and nonpharmacological interventions [9][10][11]. Of all pharmacological interventions, vaccination is the most effective strategy to prevent SARS-CoV-2 infection. Two recent reports showed that the Pfizer-BioNTech or Moderna two-dose COVID-19 vaccine regimen had a 94-95% efficacy at preventing symptomatic SARS-CoV-2 infection [10,11]. Although vaccine is the best tool to control the COVID-19 pandemic, vaccine shortages occur in many countries [12][13][14] in 2021. Therefore, nonpharmacological public health measures, such as wearing a face mask, quarantine, isolation, social distancing, and community containment, are still important and effective ways to prevent and control the COVID-19 outbreak before adequate vaccine availability [9].

About Reusing Disinfection Masks
In most countries, wearing masks in public has been an essential health protection measure during the COVID-19 pandemic. Wearing a face mask is the mainstay nonpharmaceutical intervention (NPI) to prevent being infected by SARS-CoV-2 [15]. This NPI could be effectively implemented at minimum cost and without remarkably disrupting social practices. Although the guidelines for wearing a face mask vary considerably across countries [16], there is a consensus that symptomatic individuals and those in healthcare settings should use face masks [17]. However, re-use of disposable masks is not recommended because of the potential risk of wearing a SARS-CoV-2-contaminated mask. Chin et al. reported that SARS-CoV-2 can survive on masks for as long as seven days [18].
There are currently some strategies to protect people from reusing medical masks, such as dry heat, ultraviolet germicidal irradiation, moist heat incubation, and hydrogen peroxide vapor. Most of these reports focused on the disinfection of masks in medical institutions [19][20][21][22]. However, reuse of disposable masks is not recommended because of the potential risk of wearing a SARS-CoV-2-contaminated mask. Most of these reports focused on the disinfection of masks in medical institutions [19][20][21][22]. However, reuse of disposable masks is not recommended because of the potential risk of wearing a SARS-CoV-2-contaminated mask.

Factors Associated with Reuse of Masks
The supply of masks to the general population during the COVID-19 pandemic has been challenging due to the shortage of mask production [23], thus resulting in the unhealthy behavior of reusing masks. However, studies that have examined the factors associated with mask reuse during the pandemic are limited.
A cross-sectional study enrolling 3981 non-healthcare workers in Brazil found that 71.1% of individuals reused masks during the COVID-19 pandemic and that women were less likely to reuse masks than men [24]. Another cross-sectional descriptive study involving 1000 adults in Hong Kong found that 35.4% of the subjects reused face masks during the COVID-19 pandemic, and individuals with inadequate face masks were more likely to reuse masks [25]. However, the previous study enrolled only non-healthcare workers and was inadequately controlled for potential confounders, such as knowledge on the usage of masks.
This study aimed to understand the factors associated with mask reuse and provide important information for educating individuals regarding appropriate preventive behaviors against the SARS-COV-2 infection. Therefore, we conducted a nationwide survey to determine the prevalence and factors associated with mask reuse in Taiwanese citizens during the COVID-19 pandemic.

Sampling and Data Collection
This study recruited adult Taiwanese citizens who were interviewed for COVID-19preventive behaviors and knowledge on mask usage from 18 May through 31 May 2020. A computer-assisted telephone interview system was used to randomly select participants from 23 million Taiwanese population [26][27][28]. Based on the Cochran formula, a sample size of 1075 was adequate to attain a confidence level of 95% and a margin of error of 5% for a population of 19,338,629 Taiwan adults aged ≥20 years. The distribution of participants across regions of Taiwan in this study was similar to that of the entire Taiwanese population in 2020 (p = 0.78; Table A1). This study was approved by the Institutional Review Board of Taipei City Hospital (no. TCHIRB-10904012-E), and all methods were performed in accordance with TCH-IRB guidelines and regulations.

Preventive Behaviors against SARS-CoV-2 Infection
This study evaluated participants' preventive behaviors against SARS-CoV-2 infection by using five items: wearing masks (yes/no), reducing trips to public places (yes/no), disinfecting hands with alcohol-based hand sanitizer (yes/no), improving personal immunity (e.g., getting enough sleep) (yes/no), and purchasing masks (yes/no). Each item scored one point if the participant practiced it. The preventive behavior scores against SARS-CoV-2 infection in study participants were summed and ranged from 0 to 5. Higher scores indicated the better practice of preventive behaviors against SARS-CoV-2 infection among the study participants.

Data Collection
At the time of enrollment for the study, participants underwent a computer-assisted telephone interview conducted by a trained case manager using a standardized questionnaire. This questionnaire was used to collect information about the participants' sociodemographic characteristics, preventive behaviors against SARS-CoV-2 infection, the number of masks demanded per week, knowledge on mask usage, and the reuse of masks before and during the COVID-19 pandemic. The sociodemographic characteristics included age, sex, region of residence, employment, marital status, and income. Region of residence included north, center, south, and east of Taiwan. The categories for marital status were unmarried, married, divorced, and widowed. The income level was classified as low (<10,000 New Taiwan Dollars (NTD)), intermediate (10,000 NTD to <50,000 NTD), and high (≥50,000 NTD). The number of masks demanded per week was determined by asking participants, "how many masks do you need per week to feel secure for the prevention of COVID-19 infection?" The participants' knowledge on mask usage was evaluated using five mask-related questions (Table A2). Participants were asked if they agreed that "it is important to wash hands before and after wearing a mask." Moreover, the participants were asked whether they agreed that "masks can be reused after disinfection with 75% ethanol [29]." Each question scored one point if it was answered correctly by the participant. The knowledge scores on mask usage among the study participants were summed, and the total ranged from 0 to 5. Higher scores indicated better knowledge on mask usage.

Outcome Variables
The primary outcome of this study was the reuse of masks, which was defined as using the same mask more than two times on different occasions [24].

Statistical Analyses
Descriptive statistics were used to describe the study participants' demographics, knowledge on mask usage, and mask reuse. Continuous data were presented as mean (standard deviation (SD)), and categorical variables were expressed as percentages. Multivariate logistic regression was used to determine the factors associated with mask reuse after adjusting for the participants' age, sex, income, and marital status. Since the generalized estimating equations (GEE) method can determine the relationship between independent variables and dependent variables at various time points, our study used GEE to analyze mask reuse before and during the COVID-19 pandemic among the study participants. An adjusted odds ratio (AOR) is an odds ratio that controls other independent variables in a regression model for binary outcomes. Adjusted odds ratios (AORs) with 95% confidence intervals (CIs) were reported to show the strength and direction of these associations. The p-value is the marginal significance level of statistical hypothesis testing and represents the probability of an occurring event. The variable with p < 0.05 was defined as a significant factor associated with mask reuse in the multivariate analysis. All data management and analyses were performed using the SAS 9.4 statistical software package (SAS Institute, Cary, NC, USA).

Participant Selection and Characteristics
This study included 1075 individuals who were interviewed for COVID-19 preventive behaviors and knowledge on mask usage from 18 May through 31 May 2020. The mean (SD) age was 57.36 (15.61) years, and 63.2% of the participants were female. The mean (SD) number of masks demanded per week was 4.97 (2.47) ( Table 1). Most (82.2%) participants reported mask reuse during the pandemic, which was significantly higher than that before the pandemic (72.7%; p < 0.001).
The most frequently practiced behavior against SARS-CoV-2 infection among the study participants was mask usage (72.8%), followed by reducing trips to public places (49.0%) and disinfecting hands with an alcohol-based hand sanitizer (47.7%). The mean (SD) preventive behavior score against SARS-CoV-2 infection was 2.26 (1.79).

Knowledge on Mask Usage during the COVID-19 Pandemic
The mean (SD) knowledge score on mask usage was 3.10 (0.94). Most (95.7%) participants agreed that it is important to wash hands before and after wearing masks ( Figure 1). Moreover, 85.8% of study participants disagreed that ethanol can decontaminate masks for reuse.

Factors Associated with the Reuse of Masks during the COVID-19 Pandemic
Multivariate logistic regression was used to identify the independent factors associated with the reuse of masks in study participants. After controlling the demographic characteristics and other covariates, participants were less likely to reuse masks if they had great knowledge on mask usage (AOR = 0.83, 95% CI = 0.70-0.99; p = 0.04) ( Table 2). The higher the knowledge score on masks usage, the less likely the reuse of face masks. Moreover, individuals with a high supply of masks were less likely to reuse masks during the COVID-19 pandemic (AOR = 0.82, 95% CI = 0.77-0.87; p < 0.001). The higher the number of mask demands per week, the lower the probability of face mask reuse. Other independent predictors for mask reuse included female sex (AOR = 1.57; 95% CI = 1.11-2.22).  Table 3 shows the generalized estimating equation model for the analysis of mask use before and during the pandemic. After controlling the demographic characteristics and other covariates, individuals were more likely to reuse masks (AOR = 1.75; 95% CI = 1.37-1.75) during the COVID-19 pandemic than before the pandemic.

Discussion
Our study found that 82.2% of individuals reused masks during the COVID-19 pandemic in Taiwan. Compared with their mask-wearing behavior before the COVID-19 pandemic, people were 1.7-fold more likely to reuse masks during the COVID-19 pandemic. Moreover, individuals who had greater knowledge on mask usage or had a high supply of masks were less likely to reuse masks during the COVID-19 pandemic.
The prevalence of mask reuse among the Taiwanese citizens was 82.2% during the COVID-19 pandemic, which was higher than the prevalence reported (71.1%) among Brazilian citizens [24] and among Hong Kong citizens (34.5%) [25]. Although wearing masks is an important strategy to control the spread of SARS-CoV-2 before an adequate supply of vaccines [15], it is not recommended that disposable masks be reused due to the potential risk of wearing SARS-CoV-2-contaminated masks. A recent report showed that SARS-CoV-2 can survive on masks for as long as seven days [18]. Since reusing masks is highly prevalent during the COVID-19 pandemic, the findings of our study suggest that it is imperative to educate people about proper behaviors related to mask usage to prevent SARS-CoV-2 infection.
Our study found that individuals were less likely to reuse masks if they had a good knowledge of mask usage. In total, 85.8% of participants disagreed that masks can be reused after disinfection with 75% ethanol. Wearing masks is the key component of NPI to prevent and control the COVID-19 outbreak [30]. Correct knowledge on mask usage not only protects individuals from being infected with SARS-COV-2 but also limits the spread of COVID-19 in the community. Although ethanol 70-95% had an efficient viricidal activity against SARS-COV-2 [31], mask decontamination using ethanol can decrease the filter efficiency and negatively affect the protective effect of masks [29]. Concerning emerging infectious diseases, it is extremely important for the public to have proper awareness and employ self-protection behaviors for community prevention [32].
The results of this study showed that individuals had a lower likelihood of reusing masks when they had a high supply of masks. During the COVID-19 pandemic, there has been a shortage of masks in many countries [23], including Taiwan [33]. The insufficient supply of masks to the general population can lead to mask reuse. Because mask reuse is associated with a higher risk of acquiring COVID-19, the government should take appropriate measures to increase the production of masks and the availability to the general population to reduce the reuse rate. A recent report in Hong Kong suggests that a stock of 90 face masks per person is adequate to avoid the reuse of masks during the COVID-19 pandemic [25].
This study showed that people were more likely to reuse masks during the COVID-19 pandemic than they did before the pandemic. Wearing masks is the mainstay NPI to help prevent COVID-19 infection [30]. Different countries have different attitudes and strategies regarding mask usage against SARS-COV-2 infection [16]. In the USA, wearing masks is recommended for riding on public transportation, health care workers, older adults or people with certain underlying medical conditions, and working at a job with large numbers of the public [34]. Moreover, an N95 respirator is recommended for healthcare personnel who need protection from SARS-COV-2 infection. In areas where the virus is circulating, disposable mask or fabric masks should be worn in crowded settings [34]. The Taiwan government has recommended wearing face masks among the healthy general population and mandated masks in public places, such as healthcare facilities and markets [7,35]. However, a high proportion of individuals have been reusing face masks during the COVID-19 pandemic.
Some limitations should be considered when interpreting the findings of this nationwide study. First, the cross-sectional study design prevented us from determining the causality between mask reuse and associated factors. Second, this study determined the prevalence and factors associated with mask reuse in adult citizens before the COVID-19 vaccine was available. Future research is needed to evaluate COVID-19-preventive behaviors and knowledge on mask usage in individuals after the availability of the COVID-19 vaccine. Finally, the external validity of our findings may be a concern, as all our subjects were Taiwanese. The generalizability of our results to other non-Asian ethnic groups requires further verification. However, our findings suggest new avenues for future research.

Conclusions
This study found that 82.2% of individuals reused masks during the COVID-19 pandemic in Taiwan. Reusing a face mask is related to an insufficient supply of masks and inadequate knowledge on mask usage. Future research is necessary to determine the quantity of masks that should be supplied to each individual avoid the unhealthy behavior of reusing masks. Moreover, the implementation of educational programs from the government is imperative to educate people on the correct knowledge and proper behavior of using masks. Informed Consent Statement: This study was conducted by analyzing datasets, and the original data were de-identified. Therefore, the Research Ethics Committee agreed to waive the informed consent due to minimal risk within the study.

Data Availability Statement:
The data for the study are available by contacting the corresponding author upon request.