Our study demonstrates that, during the peak pandemic periods of H1N1 influenza, most subjects reported increasing their personal frequency of hand washing in order to prevent infection. Similar findings were also reported in studies conducted at the beginning of the H1N1 influenza pandemic in Hong Kong . In a study from the United Kingdom (UK), 28% of subjects reported changing their hand washing behavior as a result of H1N1 influenza . When viewed together, the data from all of these studies imply that behaviors preventative of infection - such as hand washing - become more prevalent during pandemics.
Here, we found that, during the H1N1 pandemic, men reported washing their hands less frequently than women. Several previous studies have also concluded that women are more likely to follow behavioral recommendations (such as hand washing) to prevent the transmission of H1N1 influenza, SARS, or other infectious diseases [7, 8, 11, 13]. Our results also show that the majority of subjects had encountered information about hand washing (males: 91.2%, females: 94.6%) and most perceive hand washing to be an effective measure in preventing the transmission of H1N1 influenza (males: 95.7%, females: 96.1%). These results suggest that the recent public campaigns regarding H1N1 infection prevention conducted through mass media and public education have been successful in terms of public knowledge acquisition. Similar findings were observed in other studies performed during the H1N1 influenza pandemic both in Hong Kong  and the UK . However, in the present study, we demonstrate that gender significantly affects perceptions of hand washing effectiveness. Specifically, men are more likely to perceive hand hygiene to be an effective preventive measure against H1N1 infection. Interestingly, several previous studies conducted in Hong Kong during the SARS pandemic concluded exactly the opposite: these studies found that, when compared with women, men were less likely to believe that preventive behaviors were efficacious in controlling SARS [11, 14, 15]. While such differences could result from differences in study population demographics, profound differences may also exist in perceptions of hand washing between the two countries. Regardless, these conflicting findings highlight the need for additional cross-national comparative studies similar to one previous study conducted during the SARS pandemic .
Notably, our data indicate that gender also affects the participants' perceived severity of the H1N1 influenza as well as their own personal susceptibility to the disease. Not only were perceptions of illness severity higher among women, female participants were also more likely to perceive their own personal susceptibility to H1N1 influenza as higher. With regards to these findings, several previous studies conducted during the SARS pandemic  also reported similar gender-specific results. As for the perceived severity of illness and perceived susceptibility to H1N1 influenza, this study shows similar perceptions to a study conducted at the beginning of the H1N1 influenza pandemic in Hong Kong ; In the Hong Kong study, 64.0% of participants indicated that an H1N1 influenza infection would have "no impact" or "only a minor impact" on their daily life, while 59.7% of men and 42.9% women in our study held these beliefs. Furthermore, only 7.0% of men and 10.3% of women in our cohort, and 10% of participants from the Hong Kong study indicated believing that their personal probability of contracting H1N1 was "high" or "very high."
In this study, study participants who were female, who perceived the overall severity of the illness to be greater and hand washing to be effective in preventing disease washed their hands more frequently. Notably, these data correspond with results from multiple previous studies in regard to the relationship between the frequency of hand washing and female gender [7, 8, 11, 12, 17], perceived efficacy of hand washing , and perceived severity of the illness . However, information contact was not corrected with hand washing in this study. We contend that due to a ubiquitous media campaign, the public was already well informed about H1N1 influenza (males: 91.2%, females: 94.6%) by the time our survey was conducted, and thus any effect of obtaining information on hand washing behavior was likely minimized. Similar findings were observed in a previous study from the UK , where the perceived susceptibility to the illness had no additional effect on hand washing not already documented by previous studies [8–10, 12, 18].
Lastly, we examined the relationship between hand washing frequency and flu-like symptoms. Although we did not confirm H1N1 infection by viral culture or PCR, we preliminarily identified a relationship between hand washing behaviors and flu-like symptoms in men. However, as this study is cross-sectional in design, we were not able to determine causality between the variables. Nonetheless, despite being unable to confirm a causal relationship between hand hygiene and H1N1 virus transmission, the correlations identified in this study suggest a possible preventive effect of hand hygiene.
This study has notable several limitations. First, we were unable to distinguish H1N1 influenza infection from other upper respiratory tract infections among individuals who reported flu-like symptoms, as we did not use laboratory confirmation techniques. Symptom-based outcomes often lack specificity for influenza virus infections [5, 19], as they allow for variable interpretations. In our self-administered questionnaire, 'flu-like symptoms' could be construed differently by different students. However, as the survey period occurred during the peak period of the H1N1 influenza pandemic, public attention and information about H1N1 influenza can be assumed to be high. Consequently, the reliability and validity of using a descriptor like 'flu-like symptoms' may not have significantly skewed our data. Second, even though the relationship between hand hygiene and flu-like symptoms may have mixed effects on H1N1 influenza and the common cold, the contact and inhalation transmission hypotheses are relatively similar for both diseases, suggesting an overall importance of hand hygiene. Furthermore, as the survey was conducted during the peak period of the H1N1 influenza pandemic, the importance of improved hand hygiene should be emphasized. A third limitation is inherent to the study design: the use of convenience sampling - as opposed to random sampling - imposes some inherent selection bias and diminishes the internal validity. To maintain internal validity, we attempted to match the gender ratio of participants in our study with that of the general university population. Our study is further limited by the cross-sectional study design, which prevents the identification of any causal relationships, even though associations between the variables and reverse cause-effect relationships may exist. Lastly, the participants in our study were exclusively composed of students from a single university in Korea. As this does not represent the general Korean population, caution should be exercised when comparing these results with other studies.
Despite these limitations, our study provides invaluable insight into the general perceptions and preventive behaviors relating to H1N1 influenza among young Koreans during the peak of the H1N1 influenza pandemic. Korean students were found to increase their frequency of hand hygiene during the pandemic, and gender differences were apparent in attitudes and behaviors related to the prevention of influenza through the use of hand hygiene. Here, the factors that affected hand washing behavior were similar to those identified at the beginning of the H1N1 or SARS pandemics, suggesting that public education campaigns regarding hand hygiene are effective in altering individual hand hygiene habits during the peak periods of influenza transmission. Further studies conducted during different periods of pandemic influenza transmission are necessary to better describe changing patterns in public perceptions of illness, preventive behaviors, and outcomes of pandemic influenza transmission.