Knowledge about Hand Hygiene and Related Infectious Disease Awareness among Primary School Children in Germany

Hand hygiene is a cornerstone of infection prevention. However, few data are available for school children on their knowledge of infectious diseases and their prevention. The aim of the study was to develop and apply a standardized questionnaire for children when visiting primary schools to survey their knowledge about infectious diseases, pathogen transmission and prevention measures. Enrolling thirteen German primary schools, 493 questionnaires for grade three primary school children were included for further analyses, comprising 257 (52.1%) girls and 236 (47.9%) boys with an age range of 8–11 years. Out of 489 children, 91.2% participants indicated that they knew about human-to-human transmissible diseases. Of these, 445 children responded in detail, most frequently mentioning respiratory and gastrointestinal diseases, followed by childhood diseases. Addressing putative hygiene awareness-influencing factors, it was worrisome that more than 40.0% of the children avoided visiting the sanitary facilities at school. Most of the children (82.9%) noted that they did not like to use the sanitary facilities at school because of their uncleanliness and the poor hygienic behavior of their classmates. In conclusion, basic infection awareness exists already in primary school age children. Ideas about the origin and prevention of infections are retrievable, however, this knowledge is not always accurate and adequately contextualized. Since the condition of sanitary facilities has a strong influence on usage behavior, the child’s perspective should be given more consideration in the design and maintenance of sanitary facilities.


Introduction
Hand hygiene is generally accepted as the primary preventive measure for the reduction of infectious diseases [1] and a multitude of publications have investigated various At the beginning of the 2017/2018 school year, the total number of school children the thirteen primary schools was approximately 2,600, with a range of 94-340 sch children per primary school. In grade three, the number of school children was betwe 25 and 76. The number of the sanitary facilities for school children varied between 2 a 8 ( Table A2).
The questionnaire was designed for third-grade pupils of primary schools. A cons form signed by their parents or guardians allowing them to participate was a prerequis In total, the questionnaire was filled out anonymously by 494 third-graders. Since o completed questionnaire was classified as invalid due to inadequate processing, 493 va cases were included for further analyses, which represents a response rate of 76.4%.

Development of the Questionnaire
A standardized written questionnaire in German was developed in several ste including (i) group interviews as a basis for the elaboration of a (ii) pretest vers followed by the development of the (iii) final questionnaire ( Figure 1). For development of the questionnaire, two additional primary schools participated.  At the beginning of the 2017/2018 school year, the total number of school children of the thirteen primary schools was approximately 2600, with a range of 94-340 school children per primary school. In grade three, the number of school children was between 25 and 76. The number of the sanitary facilities for school children varied between 2 and 8 ( Table A2).
The questionnaire was designed for third-grade pupils of primary schools. A consent form signed by their parents or guardians allowing them to participate was a prerequisite. In total, the questionnaire was filled out anonymously by 494 third-graders. Since one completed questionnaire was classified as invalid due to inadequate processing, 493 valid cases were included for further analyses, which represents a response rate of 76.4%.

Development of the Questionnaire
A standardized written questionnaire in German was developed in several steps, including (i) group interviews as a basis for the elaboration of a (ii) pretest version followed Children 2022, 9, 190 4 of 19 by the development of the (iii) final questionnaire ( Figure 1). For the development of the questionnaire, two additional primary schools participated.
Third-graders (8-10 years old) of two primary schools were interviewed anonymously on two days in March 2018 in small groups (6-9 school children per group), focusing on their knowledge about pathogens and infectious diseases, including transmission and prevention aspects. Overall, 29 school children participated in the group interviews (girls, n = 15 (51.7%); boys, n = 14 (48.3%)). The results of the group interviews were considered for the development of the questionnaire's pilot version. This version was pretested by 26 school children (girls, n = 14 (53.8%); boys, n = 12 (46.2%); 8-10 years old) out of two thirdgrade classes at the end of May 2018 to find out whether the questionnaire corresponds to the requirement level of the target group and meets the time limits. Pretesting led to changes in terms of, e.g., layout adaptation and wording.
The final questionnaire contained sixteen questions partially divided into sub-questions. The (sub-)questions were open (n = 1), half-open (n = 5) and closed (n = 15). The questionnaire was divided into two parts: (i) knowledge about hand hygiene and (ii) health maintenance and health protection. The last page of the questionnaire was reserved for the collection of demographic data.

Data Collection and Analyses
The data collection applying the final questionnaire was conducted within approximately five weeks from 14 June to 10 July in 2018, except for one school that participated later in September 2018 due to renovations ( Figure 1). Processing of the questionnaire by the school children was timed for one school lesson (45 min). Data collection was guided step by step in each case by the same study advisor (a trained teacher). Briefly, the questionnaire was projected on the wall using an overhead projector or a white board, respectively, so that the school children could read along and know which question was to be answered. In addition, the questions were read aloud. To support concentration on the question being worked on and not to skip ahead, the school children were given a sheet of paper to cover the other parts of the questionnaire. The primary schools could decide for themselves whether a teacher would be present during data collection and whether a partition would be set up between the school children. In the pretest, both options were tried out. The primary schools could make their own decision on the teaching structure depending on the forms of learning normally preferred (e.g., cooperative forms of learning). Assistance for school children with special needs was admitted.
Statistical analyses (Pearson's chi-squared test, Fisher's exact test, McNemar's test and Wilcoxon test) and data evaluation were conducted with the Statistical Package for the Social Sciences (SPSS) version 26 and 27 (IBM, Armonk, New York, NY, USA). Statistical significance was considered at p ≤ 0.05.

Results and Discussion
For analyses, 493 valid cases of accomplished questionnaires of third-grade school children were included. The gender distribution was 257 (52.1%) girls and 236 (47.9%) boys. School children were between 8-11 years old (median, 9 years old). An age distribution by gender is shown in Table A3. Of the 493 questionnaires (valid cases), 57 questionnaires (≈11.6%) were collected later in September 2018 due to renovations at one school.
The aim of the first part of the questionnaire was to identify how often school children visited the sanitary facilities at school, how they judged the sanitary facilities at school and what impact this had on the judgement of their behavior. They were also asked about the importance they placed on hand hygiene in relation to the use of sanitary facilities at school.
At the beginning of the questionnaire, the school children had the opportunity to assign school grades (1, very good; 2, good; 3, satisfactory; 4, sufficient; 5, poor; and 6, deficient) to the sanitary facilities of their school. Most school children (30.3%; n = 149/492 valid cases) rated the sanitary facilities with the school grade 3 (mean value, 3.38) ( Table 1). Of note, close to half (43.9%) of the school children chose a school grade between 4 (sufficient) and 6 (deficient). Consistently, a similar percentage of children (44.8%) indicated that they would prefer not to use the toilet during school by choosing the response option "Mostly not at all". The distribution of girls and boys who gave this answer was almost equal (girls, n = 112 (23.0%); boys, n = 106 (21.8%); 218/487 valid cases). "I visit the toilet at school more than three times" per day was the response of only 23 school children (4.7%) ( Table 2). Lower school children from Sweden gave a median of "3" in the evaluation of school toilets (1, terrible; 5, excellent) [46]. A parent survey conducted in Giessen (Germany) asked whether their children used the sanitary facilities at school [47]. Similar to our study, children s avoidance behavior was evident in relation to toileting at school. In addition, over 75.0% of parents indicated that children predominantly use the sanitary facilities to urinate only, but less for bowel movements [47]. Swedish school children also stated that the sanitary facilities at school were more likely used for urinating [46]. To analyze the behavior in terms of toilet visiting in more detail, the respective reasons were queried ("Why do I like/Why do I don't like to go to the sanitary facilities at school?"). Out of 493 school children, 79.7% (n = 393) replied that they didn't like using the sanitary facilities at school. No significant gender disparities were noted (girls, n = 208 (42.2%); boys, n = 185 (37.5%)). Only 44 girls and 37 boys (81 school children; 16.4%) said "Yes, I like going to the toilet at school" and 3.9% (19 school children) didn't answer the question.
To investigate school children s motivation for visiting the sanitary facilities at school, the question was offered with free text input (multiple answers were possible). The majority of the school children (n = 400) responded with the sentence "No, I don't like to go to the sanitary facilities at school, because . . . ". The most common reasons for not using Children 2022, 9, 190 6 of 19 the sanitary facilities at school were the uncleanliness of the sanitary facilities and the (mis-)behavior of classmates (Table 3). An interview study with school children aged 9-16 from Sweden reported similar results [48]. The children described the sanitary facilities as unclean and named general conditions, such as the smell. Other similarities were that children also reported being disturbed by classmates or that it was uncomfortable using the sanitary facilities at school. In contrast to our study, the school children from Sweden indicated that they forgot the need to go to the toilet during break, e.g., they would rather play. As a result, the children wanted to go to the toilet during the lesson and also found it less stressful because all the other children were in class [48]. The time factor and the sanitary facilities were also mentioned by the focus groups (school children 6-11 years old) from another study performed in England [49]. In addition, some children indicated that they do not go to the toilet during lesson because they might miss the content of the lesson ( Table 3). In an Australian study, school children (6-10 years old) referred to misbehavior or disruptions by other school children in connection with the use of the sanitary facilities [50]. Of the 84 answers beginning "Yes, I like to go to the sanitary facilities at school, because . . . ", 11 answers were not informative or evaluable. Overall, 34 school children gave the answer that they felt "an urgent need to visit the school toilet". The hygiene of sanitary facilities was the second most common answer (n = 28). Further answers can be categorized as follows: general time off or time off from class (n = 5), orientation to the need (hand hygiene) (n = 5), the atmosphere of the sanitary facilities (n = 5), the equipment and function of the sanitary facilities (n = 3), the reduction of microbial pathogens (n = 1) and behavior/need of classmates (n = 1).
A further question concerned how often children practice hand hygiene before or after certain situations and whether there is a difference between the situation at school and at home? Tables 4 and 5 list the frequencies with which school children specified that they wash their hands before or after certain situations or actions. Of particular interest are the results for statements 2, 4 and 6 ( Table 4) and statements 3, 5, 6 and 10 ( Table 5). The statement "I wash my hands at school before eating, e.g., bread during the break or lunch" was affirmed by slightly less than half of the school children (48.0%); however, there was variation in terms of frequency between 23.7% (always) and 24.3% (often). Approximately one quarter completely (24.5%) and another quarter predominantly (27.4%) denied hand washing prior to eating. While children are taught to "wash their hands before eating" prior to school enrollment in day care centers, about half of the children do not practice this at school. This is in contrast to the situation at home, where significantly more, i.e., about three-quarters of the school children (77.4%, p < 0.001) answered that they washed their hands always or, at least, often (Table 5; statement 3). Thus, knowledge of hand washing before eating is already developed and it is also practiced by the majority at this age. Hence, other conditions may compromise their implementation at school. That only one sink per classroom is provided may contribute to this discrepancy, and the answers of the school children (keyword: time factor) as well as the proportion of average class sizes at the participating schools (n = 22.7) support this hypothesis. Moreover, if school children want to overcome this situation by using the primary school sanitary facilities, they find themselves in the dilemma between the one-sink situation of their classroom and the negative connotation of the toilet environment. Thus, avoidance behavior is provoked, as has been shown, also, by others. The extent to which the sanitary facilities (sinks and toilets) are used by school children depends on their condition [35]. School children aged 9-11 years in England and Sweden perceived the sanitary facilities at school as unclean, stinky and unpleasant (likewise in relation to disturbances by other children) [51]. A study that focused on the conditions of hygiene in schools revealed that the sinks in primary schools were better equipped compared to other types of school. However, the sinks in the classrooms were less well equipped than the sinks in the sanitary facilities. It was also evident that classroom sinks were used less by children to wash their hands and more frequently, for example, by teachers to rinse the blackboard sponge [52]. Thus, rethinking of the importance and usage of sinks in classrooms and their value for hand hygiene to prevent the development and transmission of infections is necessary. However, other uses (e.g., washing utensils used in art lessons) do not necessarily have to be excluded.
Avoidance of using the sanitary facilities at school may have direct negative impacts for the children, e.g., constipation and urinary tract infections [51]. In addition, this avoidance behavior may also have an indirect negative effect on the children's goal of washing hands only at the sanitary facilities (e.g., before eating and after the break), which is important for infection prevention.
An even worse situation became apparent when the answers to the statement "I wash my hands at school after the break" were analyzed (Table 4; statement 6). The majority of the school children indicated that they "never" or "seldom" wash their hands (73.2%). In contrast, in the home setting (Table 5; statement 6), 36.4% of the school children answered that they wash their hands "never" or "seldom" after playing outside. The results of both statements show a difference of 36.8%. Between the results of both statements is a significant difference (p < 0.001) that indicates that there is a change in children's behavior between school and home. The reasons for this may be due to more intensive observation at home and/or the much better conditions for hygiene procedures at home. In connection with the results for statement 10 (Table 5) regarding hand washing when coming home, it would be interesting to know whether the distribution of answers would be different if the questionnaire were conducted today in light of the COVID-19 pandemic.
Of particular interest were the answers to the question: "How often do I wash my hands after going to the toilet?" (Table 4). For 76.7% of the school children, the answer was "always" at school and only 1.2% of the children indicated that they never wash their hands in this situation. This percentage is not statistically significantly different (p = 0.396; Wilcoxon test; Z-score = −0.849) from the responses related to hand hygiene after toileting at home ("always", 75.7%; "never", 1.0%) ( Table 5). The answers to another question confirmed relatively well-developed hygiene awareness of handwashing after toilet use. The school children were asked to write a rationale (free text) regarding why hand hygiene after toilet use is important for them. Multiple answers were possible. The responses indicated that washing hands after going to the toilet is important for most school children (98.5%; 451/458 valid cases). The most given reason was related to the notion of "pathogens". The children noted that pathogens are, e.g., on the hands or on the sanitary facilities (e.g., toilet). A further 115 answers of the school children focused thematically on the development of infections. Thus, with a certain degree of probability, these results indicated that school children at this age already have knowledge of the importance of practicing hand hygiene in order to maintain individual and collective health. Furthermore, it is noticeable that school children in primary schools have the knowledge that bacteria exist on their hands. However, the existence of other kinds of pathogens (e.g., viruses or parasites) as well as an idea of pathogenic ("bad") versus non-pathogenic, commensal or even mutualistic ("good") bacteria as part of the human microbiota ("physiological flora") is unknown at this age. The knowledge that hand hygiene is important to remove microbial pathogens was also supported by the results for focus groups (children aged 6-11 years) in England [49].
Since awareness may differ for bowel movement and urination procedures, particularly in the case of boys, this respective question was included. Over 95.0% of the school children found it "important" or "very important" to wash their hands after a bowel movement. Stratified by gender, 51.6% of the girls and significantly less boys (45.1%) affirmed this statement ( Figure A1a) p = 0.025; chi-squared test). For only 3.3% of the school children, it was "not important" or only a "little bit important" to wash their hands after a bowel movement. In the case of urination ( Figure A1b), 431 (88.5%) school children considered that it is "important" or "very important" to wash the hands thereafter. Statistical verification shows that the responses "important" or "very important" differed significantly by gender (p = 0.003; chi-squared test). Around 11.5% of the school children perceive hand hygiene as "not important" or a "little bit important" in this case. That is a percentage increase of 8.2% in comparison to the bowel movement results. The sanitary facilities of all participating schools had urinals in the toilet rooms of the boys. Here, it would be of interest to determine the boys' views on hand hygiene when they would use either the toilet or the urinal to urinate.
School children may visit the school sanitary facilities not only for the actual purpose of use. Depending on their location (e.g., outside the main school building next to the playground) they may use the sanitary facilities to play (e.g., hide-and-seek) or to escape supervision. Within the questionnaire, two examples (sanitary facilities as a "hiding place" and as offering an opportunity to share secrets) were given so that the school children have an idea what is meant by the question. As visible in Figure A1c, it is "important" or "very important" for 50.0% of the school children (n = 245) to wash hands regardless of the reason for visiting the toilets. Exactly the same number of school children answered "not important" or a "little bit important".
Pairwise comparison of the results concerning the importance of hand hygiene revealed significant results for "bowel movement" vs. "urination" (p < 0.001; Wilcoxon test; Z-score = −12.904), "bowel movement" vs. "visiting toilets for other reasons" (p < 0.001; Wilcoxon test; Z-score = −16.776) and "urination" vs. "visiting toilets for other reasons" (p < 0.001; Wilcoxon test; Z-score = −14.159). Thus, a tendency was observed that bowel movement received the highest awareness concerning hand washing, followed by urination and visiting toilets for other reasons.
A further point of the questionnaire addressed the practical hand washing skills of the school children. They were asked to sort the displayed pictures of hand hygiene steps in the right order by adding the numbers one to five to the pictures (Figure 2). Knowing the correct sequence of hand washing steps is important to facilitate the practical teaching of effective hand hygiene in children [49]. A total of 385 school children (78.1%) were able to sort the hand hygiene steps correctly. Of the 108 school children (21.9%) who weren't able to sort the order correctly, 45 (41.7%) of the school children started the hand hygiene steps with picture two "Pull the soap out of the soap dispenser" instead of "Get your hands wet", and 86 school children (79.6%) selected as the second hand hygiene step "Get your hands wet" instead of "Pull the soap out of the soap dispenser". Overall, the answers of 59 school children included more than one mistake. Four-hundred-and-eighty-five school children (98.4%) correctly selected "Dry hands well" (as step five).
bowel movement received the highest awareness concerning hand washing, followed by urination and visiting toilets for other reasons.
A further point of the questionnaire addressed the practical hand washing skills of the school children. They were asked to sort the displayed pictures of hand hygiene steps in the right order by adding the numbers one to five to the pictures (Figure 2). Knowing the correct sequence of hand washing steps is important to facilitate the practical teaching of effective hand hygiene in children [49]. A total of 385 school children (78.1%) were able to sort the hand hygiene steps correctly. Of the 108 school children (21.9%) who weren't able to sort the order correctly, 45 (41.7%) of the school children started the hand hygiene steps with picture two "Pull the soap out of the soap dispenser" instead of "Get your hands wet", and 86 school children (79.6%) selected as the second hand hygiene step "Get your hands wet" instead of "Pull the soap out of the soap dispenser". Overall, the answers of 59 school children included more than one mistake. Four-hundred-and-eighty-five school children (98.4%) correctly selected "Dry hands well" (as step five).
The second part of the questionnaire dealt with questions about the maintenance of health and protection against diseases. The majority of the school children (n = 439/491 valid cases; 89.4%) ticked the answer option "always" or "often" when asked about the statement "I wash my hands several times a day" as a possible measure to maintain individual health. About 10.6% of the school children chose the answer option "rarely" or "never" and in this case significantly more boys (n = 36) as opposed to 16 girls (p = 0.001/chi-squared test). The question "How can you protect yourself against disease?" comprised seven statements, for which the school children were asked to answer with "right" or "false" ( Table 6). The statements 1-7 were answered correctly by more than 80.0% of the school children. Of particular relevance is the fact that 99.4% of the school children (489/492 valid cases) responded correctly to the statement "I wash my hands with soap." Regarding statement 1 ("I can be vaccinated against specific diseases."), it should be noted that school children may have answered incorrectly (5.1%) for several reasons, e.g., the school children may know that they have not been vaccinated against certain diseases or they may know that their parents have objections to vaccination. Covering an open wound with a plaster or bandage to protect against disease (statement 3) was considered "right" by 450 school children (91.8%). Within the questionnaire survey, this statement was accompanied by the remark that it was meant to be an "open wound" and not a "slight skin abrasion". However, for 40 school children (8.2%) this statement was false in connection with protection against disease, probably due to domestic experience of healing wounds without the protection of a sticking plaster. When analyzing the next statement "I keep distance from ill people who are suffering, e.g., from a cough or sniffles", it is notable that 52 school children (10.6%) responded "false". Presumably school children at this age keep less of a distance from people in their family environment (e.g., parents or siblings) if they are ill because of their special need for close physical contact at this age. Statement 6, asking about playing with the computer or watching TV as a "protective measure", was answered in the right way by 412 school children (84.9%). The other 73 school children (15.1%), of which were significantly (p < 0.001) more boys (n The second part of the questionnaire dealt with questions about the maintenance of health and protection against diseases. The majority of the school children (n = 439/491 valid cases; 89.4%) ticked the answer option "always" or "often" when asked about the statement "I wash my hands several times a day" as a possible measure to maintain individual health. About 10.6% of the school children chose the answer option "rarely" or "never" and in this case significantly more boys (n = 36) as opposed to 16 girls (p = 0.001/chi-squared test).
The question "How can you protect yourself against disease?" comprised seven statements, for which the school children were asked to answer with "right" or "false" ( Table 6). The statements 1-7 were answered correctly by more than 80.0% of the school children. Of particular relevance is the fact that 99.4% of the school children (489/492 valid cases) responded correctly to the statement "I wash my hands with soap." Regarding statement 1 ("I can be vaccinated against specific diseases."), it should be noted that school children may have answered incorrectly (5.1%) for several reasons, e.g., the school children may know that they have not been vaccinated against certain diseases or they may know that their parents have objections to vaccination. Covering an open wound with a plaster or bandage to protect against disease (statement 3) was considered "right" by 450 school children (91.8%). Within the questionnaire survey, this statement was accompanied by the remark that it was meant to be an "open wound" and not a "slight skin abrasion". However, for 40 school children (8.2%) this statement was false in connection with protection against disease, probably due to domestic experience of healing wounds without the protection of a sticking plaster. When analyzing the next statement "I keep distance from ill people who are suffering, e.g., from a cough or sniffles", it is notable that 52 school children (10.6%) responded "false". Presumably school children at this age keep less of a distance from people in their family environment (e.g., parents or siblings) if they are ill because of their special need for close physical contact at this age. Statement 6, asking about playing with the computer or watching TV as a "protective measure", was answered in the right way by 412 school children (84.9%). The other 73 school children (15.1%), of which were significantly (p < 0.001) more boys (n = 58), ticked the wrong answer. However, this statement might be considered from the perspective that games on digital media are played alone and thus there is no contact with other individuals, which could be interpreted as implying protection against disease. In order to obtain detailed information from the school children, open questions were developed that focused on three key aspects: human-to-human transmissible diseases, cause of diseases and transmission routes of diseases. Multiple answers were possible; thus, both correct and incorrect partial answers may appear concurrently.
First, 446 of a total of 489 school children indicated that they knew about human-tohuman transmissible diseases; 445 written answers were noted, including wrong answers. Infections of the respiratory and gastrointestinal tract were listed most frequently, followed by childhood infections; other infectious diseases were mentioned sporadically (Table 7). In general, 63 wrong or partially wrong answers were given, e.g., cancer and allergies. Instead of diseases, symptoms of diseases were also mentioned, e.g., cough, sniffles, fever, vomit and diarrhea, that were not included in the wrong answers. Thus, school children at this level do not differentiate between infection and symptom(s). However, it was astonishing how many different disease entities (overall, n = 24) were mentioned by them.
Second, 58.4% of the school children responded that they know what can cause such transmissible diseases (affirmative answers, n = 281/481 valid cases). The related open question was completed by 291 school children (including wrong answers). While answers such as microbes, germs, bacteria, fungi, parasites and/or viruses were expected, only 41/291 (14.1%) school children responded as anticipated. Although only a few school children noted bacteria and/or viruses as a cause of a transmissible disease, these terms can already be part of the acquired vocabulary of school children at this level because they used these terms to answer other questions in this questionnaire (e.g., question about the importance of hand hygiene after using the toilet). Concerning the "incorrect" answers, it was interesting that 117 (40.2%) named an external factor, such as the situation of being outside with inadequate clothing, e.g., "Yes, if, for example, you walk around outside in winter without a scarf or cap" (girl, 8-year-old). Additionally, an inappropriate hygiene behavior was the content of 52 (17.9%) answers. The third and fourth most frequent "false" answers included symptoms of infections (n = 35; 12.0%) and ways of transmission of infections (n = 28; 9.6%). Third, compared to 161 (34.3%) school children who gave a negative reply, 308 (65.7%) school children stated that they know how infections can be transmitted. While only 469 (valid cases) school children answered this yes/no question, a total of 332/490 (67.8%) school children filled in the subsequent answer field. The most mentioned infection route was transmission by droplet infection (n = 161, 48.5%), followed by smear infection (n = 133, 40.1%) and indirect transmission (n = 2, 0.6%). Other transmission routes of infections were not mentioned. Further answers or partial answers were declared as incorrect because there was no relation to putative transmission routes noting, for example, pathogens (n = 32), infections or symptoms (n = 3) and contamination (n = 19). Some comments have been categorized twice because the given comment could not be clearly assigned to one of the defined categories or because it addressed multiple categories.
Using exemplary statements that were intended to stimulate the imaginations of the participants, more data on the knowledge of school children about the transmission routes of pathogens were collected (Table 8). Here, school children were to imagine that they had a cough, sniffles or diarrhea and how they could contribute to avoid the transmission of those contagious diseases to fellow humans. The school children had the choice to answer whether the statement was right or false. Eighty-five percent of the school children answered all the statements correctly. A wrong answer to the statements was given for 10.0% or less of all statements, except for one statement ("I don't spit on the floor.") that was ticked by 73 school children (14.9%) incorrectly. In general, no significant differences between the answers of girls and boys can be noticed. Overall, our study has the following limitations: Only primary schools of a defined administrative area were included to meet the EUREGIO affiliation but also to avoid influences of the educational structures in Germany, which are organized on the federal state level. A future German-wide or European study addressing this point is warranted. The participating primary schools were diverse in terms of various factors, such as school size and school location (urban or rural). Moreover, the teaching of and awareness of topics related to hygiene and infections in the broadest sense could differ between schools and classes. Further to this, it is to be mentioned that general hygiene behavior and awareness regarding infectious diseases, especially with respect to prevention measures, may be handled differently and have varying connotations in different families. In the survey form chosen in this study (standardized written questionnaire presented face-to-face) it should be noted that the interviewer (study advisor) and the respondents (school children) are in a complex interaction during the questioning. As a consequence, the interviewer's behavior may have an influence on the respondents' answers [53]. However, to limit this influence, the data collection was managed in our study by the same study advisor.

Conclusions
In summary, our study revealed that hand hygiene was an important measure for children of primary schools after visiting the toilet facilities. However, the importance of hand hygiene for the school children varied depending on the purpose of visiting the toilet. It was highest after bowel movement and decreased in its extent after urination and visiting the toilets for purposes other than those for which they were intended. We can conclude that the main objectives of school children for hand hygiene after going to the toilet were the removal of pathogens from their hands and the prevention of infectious diseases. The study revealed that although primary school-aged children already know the term "bacteria", they are generally unable to distinguish between beneficial ("good") and pathogenic ("bad") bacteria. It is interesting to note that the term "viruses"-at least in the pre-COVID-19 era-was used much less frequently. While the school children of this age were able to name respiratory and gastrointestinal infections, they were not yet able to differentiate precisely between infections and symptoms.
It is particularly noteworthy that the majority of school children included in this study don't like to use the sanitary facilities at their school. Moreover, many school children even avoided using the toilets at school, regardless of gender. The reasons given were diverse but predominantly related to the poor cleanliness and general conditions of the sanitary facilities. Our results underscore the importance of continually addressing the topic of school sanitary facilities and they should alert the respective school supervising authorities. Our study emphasizes that health promotion among school children is a participatory and inclusive process that must actively involve not only the institution "school" but also the parents and the children. The results provide the opportunity to highlight the importance of hand hygiene in the semi-public environment, especially in the sanitary facilities of the primary school, which could raise interest in this topic among guardians, school personnel, school authorities and political authorities.
In general, scientific research questions that deal with the target group of children should increasingly involve them and question them directly. Although school children at the primary school level are interested in hygiene-and infection prevention-related issues, there are knowledge gaps that prevent appropriate hygienic behavior in the semipublic environment of sanitary facilities. The ongoing COVID-19 pandemic underlines the importance of sticking to hygienic rules. Funding: This research was part of the joint projects "EurHealth-1Health" and "health-i-care" and was supported by external funding within the framework of the INTERREG VA "Germany-The Netherlands" program (EU/INTERREG VA-681377 to K.B. and EU/INTERREG VA-122084 to S.S.).

Institutional Review Board Statement:
Ethical review and approval were waived because the research related to common educational practices as part of the regular school curriculum based on completely anonymized questionnaires.

Informed Consent Statement:
Signed informed consent from the parents or guardians of the children allowing them to participate was obtained as a prerequisite.

Data Availability Statement:
The datasets generated and/or analysed in the current study are not publicly available due to data privacy, but are available from the corresponding author on reasonable request.  1 Due to rounding to one decimal position, the percentage values do not always add up to 100.