Correlation Between Mask Compliance and COVID-19 Outcomes in Europe
Published: April 19, 2022 (see history)
Cite this article as: Spira B (April 19, 2022) Correlation Between Mask Compliance and COVID-19 Outcomes in Europe. Cureus 14(4): e24268. doi:10.7759/cureus.24268
Masking was the single most common non-pharmaceutical intervention in the course of the coronavirus disease 2019 (COVID-19) pandemic. Most countries have implemented recommendations or mandates regarding the use of masks in public spaces. The aim of this short study was to analyse the correlation between mask usage against morbidity and mortality rates in the 2020-2021 winter in Europe. Data from 35 European countries on morbidity, mortality, and mask usage during a six-month period were analysed and crossed. Mask usage was more homogeneous in Eastern Europe than in Western European countries. Spearman’s correlation coefficients between mask usage and COVID-19 outcomes were either null or positive, depending on the subgroup of countries and type of outcome (cases or deaths). Positive correlations were stronger in Western than in Eastern European countries. These findings indicate that countries with high levels of mask compliance did not perform better than those with low mask usage.
Universal masking has been introduced during the coronavirus disease 2019 (COVID-19) pandemic at an unprecedented global scale as an important tool to curb viral transmission among potential susceptible persons. Face masks still are one of the most significant and controversial symbols in the fight against COVID-19. Two large randomised controlled trials about mask effectiveness performed during the pandemic came out with mixed results [1,2]. Several studies that analysed the effect of masks on the general population (ecological studies) have concluded that masks were associated with a reduction in transmission and cases [3-7]. However, these studies were restricted to the summer and early autumn of 2020. From March 2020 onwards, country after country instituted some form of mask mandate or recommendation. The stringency of these measures varied among the different countries and they, therefore, resulted in different proportions of mask compliance, ranging from 5% to 95% . Such heterogeneity in mask usage among neighbouring countries provided an ideal opportunity to test the effect of this non-pharmaceutical intervention on the progression of a strong COVID-19 outburst.
Materials & Methods
This analysis aimed to verify whether mask usage was correlated with COVID-19 morbidity and mortality. Daily data on COVID-19 cases and deaths and on mask usage were obtained for all European countries. The rationale behind the choice of European countries for comparison was fourfold: (1) availability and reliability of data; (2) a relative population homogeneity and shared history of epidemics (comparing countries from different continents may bring too many confounding factors); (3) similar age stratification and access to health assistance; and (4) divergent masking policies and different percentages of mask usage among the different populations, despite the fact that the entire continent was undergoing an outburst of COVID-19 at the time period analysed in this study.
Data were collected from the following Eastern and Western European countries: Albania, Bosnia and Herzegovina, Bulgaria, Croatia, Czechia, Hungary, North Macedonia, Poland, Romania, Serbia, Slovakia, Slovenia, Belarus, Estonia, Latvia, Lithuania, Republic of Moldova, Ukraine, Austria, Belgium, Denmark, Finland, France, Germany, Greece, Ireland, Italy, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland, United Kingdom, and Northern Ireland. The inclusion criterion was a population size higher than one million people.
Data on morbidity, mortality, and mask usage were retrieved from the Institute for Health Metrics and Evaluation (IHME) at the University of Washington . Data from IHME were downloaded on 14th February 2022. IHME mask data sources are the Delphi Group at Carnegie Mellon University and the University of Maryland COVID-19 Trends and Impact Surveys, in partnership with Facebook, Kaiser Family Foundation, and YouGov COVID-19 Behaviour Tracker Survey (https://www.healthdata.org). Data on vaccination were obtained from Our World in Data (OWID)  on 4th April 2022.
Data from 35 European countries on morbidity, mortality, and mask usage during a six-month period were collected and analysed. Spearman’s correlation analyses and Shapiro-Wilk normality checks were in JASP (version 0.15; University of Amsterdam, Amsterdam, Netherlands)  and linear regressions in Wolfram Mathematica 13.0 (Wolfram Research, Inc., Champaign, Illinois) .
This brief communication reports the correlation between the proportion of mask usage in the population and the number of cases (per million) and deaths (per million) from October 2020 to March 2021 in 35 European countries (Table 1). For this analysis, all European countries, including West and East Europe, with more than one million inhabitants were selected, encompassing a total of 602 million people. All analysed countries underwent a peak of COVID-19 infection during these six months (Figures 1, 2). The average proportion of mask usage in the referred period was 60.9% ± 19.9%, slightly higher in Eastern than in Western Europe (62.1% and 59.6%, respectively). However, the level of mask compliance was considerably more homogeneous in East (SD = 13.4%) than in West European countries (SD = 25.4%)…