As the years passed, the frequency of handwashing always/frequently increased among adults, especially in 2020, the COVID-19 pandemic era. The tendency was evident in the following cases: women and those vaccinated against influenza. The frequencies of handwashing after going out and handwashing with soap tended to increase in 2020 when self-perceived health status was good compared with when it was poor in 2013. Those practicing physical distancing due to COVID-19 were more likely to wash their hands always/frequently.
In this 5-year survey, 44.7% of adults responded that they wash their hands always/frequently, while the rest said they did not. This is consistent with findings of previous studies that fewer people wash their hands always/frequently in the absence of special events, such as pandemics or handwashing campaigns [17, 30, 33].
There is a very close positive linear relationship between years with the incidence of communicable diseases and handwashing. This is especially evident in 2020 during the COVID-19 pandemic. As the incidence of communicable diseases mostly affected public awareness in a specific year, the likelihood of handwashing always/frequently was high. In previous empirical surveys, the factors influencing handwashing behavior included campaigns, handwashing accessibility, and health beliefs [34]. In Korea, campaigns and handwashing accessibility did not change significantly during the survey period used in this study (2013, 2015, 2017, 2019, and 2020). Since 2014, the Korean government has not implemented a nationwide long-term handwashing campaign. The number of public toilets nationwide was 58,248 in 2014 [35] and 56,451 in 2020 [36], which is equivalent to 1 toilet per 1,000 people.
Additionally, handwashing can be affected by the severity of the communicable diseases in terms of their causes, period of the epidemic, age distribution of infection, the incidence rate in residential areas, and mortality. The incidence of communicable diseases designated by law per 100,000 people was low (148.4) in 2013, and tended to increase thereafter. The incidence in 2015 was 185.7 people. MERS accounted for 0.14% of the total communicable diseases, but it had an impact on public awareness because a high fatality rate (20.5%) was recorded within a short period (46 days) in areas with high incidence (Seoul & Gyeonggi, regional incidence: 63.2%) [2, 37]. The incidence of communicable diseases designated by law per 100,000 people in 2017 was 295.5, and scarlet fever accounted for 12.5% of the total communicable diseases. The incidence of scarlet fever increased by 91.7% compared with that in the previous year, and it affected certain age groups (3–6 years, incidence by age: 71.5%) and regions (Gyeonggi, regional incidence: 30.1%, ranking of the regional incidence by population: first) [2, 38]. The incidence of communicable diseases designated by law per 100,000 people in 2019 was 307.7 people, and viral hepatitis A accounted for 9.5% of the total communicable diseases. The incidence of viral hepatitis A increased by 622.1% compared with that in the previous year because of a specific cause (the consumption of contaminated shellfish) in certain age groups (30–40 years, incidence by age: 72.7%) and region (Gyeonggi, regional incidence: 30.7%; Daejeon, ranking of the regional incidence by population: first) [2, 39]. The incidence of communicable diseases designated by law per 100,000 people in 2020 was 281.6 people, and COVID-19 cases accounted for 35.4% of the total. COVID-19 affected a specific period (December, monthly incidence: 45.0%), age group (from fifties to sixties, incidence by age: 35.4%), and regions (Seoul & Gyeonggi regional incidence: 57.4%, ranking of the regional incidence by population: first) [1, 2, 40].
The incidence of communicable diseases increased by year, and women were more likely to wash their hands always/frequently compared with men. This is consistent with results of previous studies showing that women have better hand hygiene than men [30, 41, 42]. Sex can affect severity and individual susceptibility to disease [43]. This may help women become more aware of and prevent communicable diseases. In previous studies, women were more likely to perceive H1N1 influenza infection as fatal [43]. Furthermore, women were more likely to follow recommendations for preventing H1N1 influenza, severe acute respiratory syndrome, and other communicable diseases than men [41, 44]. People vaccinated against influenza were more likely to hand wash frequently/always in years with a high incidence of communicable diseases. This may be due to concerns about communicable diseases. Prior studies have shown that people worrying about risk take measures to reduce risk, and people who are concerned about communicable diseases try to follow preventive measures, such as handwashing [45]. The more people worried about seasonal influenza in France, the more likely they were to get the A/H1N1 influenza vaccine. Old age and the presence of chronic disease in Europe were closely related to vaccination [46, 47].
People with good self-perceived health status in 2020 were more likely to wash their hands always/frequently compared with those with bad self-perceived health status in 2013. The trend was particularly evident in handwashing after going out. People following physical distancing due to COVID-19 were also more likely to always wash their hands than those not following physical distancing. COVID-19 is a highly contagious disease, and our investigation was conducted before its vaccine was released; thus, there was high anxiety about infection among the public. COVID-19 is transmitted through respiratory droplet spread; therefore, individuals need to be careful when using public transportation or crowded facilities. Handwashing has been recommended by the government as a representative prevention method for communicable diseases.
To the best of the authors’ knowledge, this is the first study to identify an association between communicable diseases, focusing on COVID-19, and routine handwashing by years using national survey data of adults. Data from random cluster sampling are sufficiently representative of Korean adults.
The limitations of this study are as follows. First, the causality between communicable diseases, specifically COVID-19, and routine handwashing is obscure. As this study had a cross-sectional design, it was difficult to determine causality [48]. Nevertheless, while comparing the survey responses over 5 years, we assessed the change in handwashing behavior over time. Second, the specific frequency or duration of handwashing was not investigated. However, handwashing frequency and cases allow inference of its practice. Third, changes in handwashing related to communicable diseases in infants and adolescents are unknown. In previous studies, there were a few cases (after using the toilet/going out, before eating) of less handwashing among teenagers; therefore, further studies are needed [49, 50].