In our study, we ecorded young adolescents' level of awareness on HPV and its vaccination, was a cornerstone for the organization, modernization and implementation of primary preventive programs, including the vaccination against cervical cancer. The vaccination against the HPV may be proven to be the best strategic option, the above reduces the risk of developing the disease in the long run, and in long term the cost effectiveness to the country's health system. In fact, vaccinating girls at a young age, before the initiation of sexual activity, is preferred nowadays mainly for 2 reasons: First of all, at that time the young body has not yet been exposed to the virus and secondly, the immune response with antibody production is much greater at younger ages .
According the analysis of the data of the present study, it is indicated that the level of knowledge about the HPV and the vaccination against cervical cancer, is not statistically significant between the two genders. The hypothesis that girls are more aware on this issue than boys, is confirmed in most research studies. Durosoy et al attributed the fact that the majority of participants who were informed about the effects of HPV were women, to that the awareness campaigns were aimed mainly to girls and women and less to men and boys . Similarly, Gerend and Magloire noticed that female students reported higher awareness and knowledge level about the HPV and its related diseases, than their classmates .
Furthermore, in a recent study, Tung and his colleagues revealed that female students had a higher level of knowledge and a more positive attitude towards the HPV, than male participants . Similarly, Patel and his colleagues indicated that young adolescent women were more aware of the HPV and HPV vaccination than men. This finding probably reflects the fact that HPV is mainly considered a women's health issue and that most countries currently recommend the HPV vaccination only for women . However, studies have shown that homosexual male adolescents have a higher level of knowledge about the HPV and the effects of HPV infection than the heterosexual ones, mainly attributed to the fact that the virus is also associated with the development of anal cancer [20, 21].
Regarding the vaccination against the HPV, it is noticed that girls demonstrate a higher willingness on this matter than males. The above result is confirmed by many studies from the international literature. In 2015, Khurana and his colleagues indicated that the acceptance of cervical cancer vaccination among unvaccinated adolescent men, was much lower than in girls, emphasizing the importance of education in increasing the vaccination coverage among the male population . Moreover, in a recently published systematic review, the increased acceptance of the HPV vaccines was mainly attributed to the greater willingness for vaccination against cervical cancer, by young adolescent women .
Place of residence
The present study revealed that the residence area of young adolescent students is strongly related to the level of knowledge about the HPV and their willingness to be vaccinated against cervical cancer. It is concluded that students living in urban centers, are more aware of the HPV and HPV vaccination than students living in rural areas. Students residing in a village tend to be unwilling to be vaccinated against cervical cancer.
The majority of scientific studies that have investigated the HPV coincide with the above expected result, reinforcing the hypothesis that the level of knowledge about the virus and its vaccination, varies not only in different countries, but also among regions of the same country. Durusoy and his colleagues concluded that there is a wide range of behavioral approaches to the intention to vaccinate against the HPV among countries, with the Western ones demonstrating higher rates of acceptance of HPV vaccines, than the Easterns. The same study also indicated that participants from Turkey's western region, were more willing to be accepted and to be included in a preventive vaccination program, than the residents of the mainland .
Moreover, quite significant seems to be the variation in the level of knowledge about the HPV and HPV vaccination in European countries. A higher level of awareness is observed among Italian adolescence, approximately two years after the introduction of HPV vaccines , while the lowest level of knowledge is noticed in Sweden, three years before the implementation of the national vaccination program . Studies from Hungary and the Netherlands have also been demonstrating a higher level of awareness about the HPV, compared to Germany, suggesting that the knowledge about the virus and HPV vaccination is a multifactorial issue, the solution of which seems not to be only the introduction of a national vaccination program, against cervical cancer [26, 27, 28, 29, 30].
According the results of our study, it is concluded that the annual family income is statistically significantly related to the level of knowledge about the HPV and the willingness to undergo vaccination. It is noticed that the higher the family income, the higher the level of awareness about the HPV. Typically, students who state that their annual family income is low, are less likely to be vaccinated against the HPV virus.
The outcome of a study conducted by Durosoy and his colleagues is similar. The authors indicated that participants with a higher socioeconomic status were more likely to be vaccinated against the HPV, than the economically weaker counterparts . Similarly, Mortensen in 2010 revealed that vaccination acceptance among adolescents, was associated with a higher level of education and higher socioeconomic status of their parents, without being able to pinpoint which of the two factors was the most important . In 2016, Schülein and his colleagues found that the educational level of parents, was slightly most important factor than the socioeconomic level, in terms of acceptance of HPV vaccination .
In contrast, a recent study from Slovenia, aiming to determine the relationship between socioeconomic factors and cervical cancer vaccination, indicated that the lowest vaccination rates were not statistically significantly correlated with the lower average family income, nor was there any relationship between higher education ratios and the immunization rate of the participants in the study .
The marital status of the parents of the participants in this study was not statistically significantly related to the level of knowledge about the HPV and the willingness to be vaccinated against cervical cancer. However, regardless of the marital status and the lack of correlation between the examined factors, a strong tendency to be vaccinated against the HPV among the participants was found.
Similarly, in a previous study aiming to determine whether parents would allow their children to be vaccinated against the HPV and which variables could influence their decision, the authors concluded that marital status was not related statistically significantly with the acceptance of HPV vaccination . In contrast, a recent study indicated that participants' family status, along with other socio-demographic factors, such as race, nationality, maternal education, health care provider composition, family income, and the age of the unvaccinated daughter, appear to be statistically significantly related to one or more factors identified as barriers to the decision to vaccinate against cervical cancer .
The analysis of the data of our study revealed that nationality is statistically significantly related to the level of knowledge about the HPV and the willingness to vaccinate. Greeks appear to be much more informed about the virus, than students of Albanian or other nationalities. However, it is necessary to point out the observed disproportion of nationalities among the participants, as 95.6% are of Greek nationality, which does not allow us to assess the result excellently and with great accuracy.
Similarly, a study from Italy indicated lower vaccination coverage rates against the HPV in foreigners, compared to Italian citizens . Furthermore, other studies involving female adolescents of national minorities from degraded areas, found that the rates of HPV vaccination were lower compared to those of privileged ones [36, 37]. In contrast, a recent Canadian population study found that school vaccination programs can lead to higher vaccination coverage rates, even in areas inhabited by a larger percentage of national minorities .
Health Education as a means of improving the knowledge level about the HPV and the vaccination willingness.
In an effort to approach and interpret the main outcomes of this research study, it appears that through Health Education, using targeted informative intervention, a statistically significant increase in both the level of knowledge about the HPV and the infection caused by it, is recorded, as well as to the adolescents’ willingness to be vaccinated against HPV and cervical cancer.
Furthermore, towards the same research axis and direction is the publication of a systematic bibliographic review by our research team. The conclusion we have drawn, is that adolescents are not sufficiently informed about the HPV and the HPV preventive vaccination. In order to improve the level of knowledge about the virus and the consequences of HPV infection, is mandatory to provide information through the framework of compulsory education, primary health care and the development of informative interactive interventions. The knowledge and receptive susceptibility to HPV infection and to HPV-related health issues, demonstrate the urgent need for a well-designed training program nowadays, in order to bridge the gap between HPV awareness and vaccine acceptance .
Previous studies have also indicated that informing young women, is an important factor in shaping positive thinking and perception towards the vaccination against HPV [17, 20, 40]. In 2014, Lee and his colleagues highlighted the role of school environment, which should provide young teens with more information about the prevention of cervical cancer, while enhancing the health education. The purpose of the above is the proper information of the students, concerning the severity of the disease, in order to be achieved higher rates of participation in a vaccination program against cervical cancer .
On the other hand, it has beenindicatedby other studies, that the participation and completion of a preventive HPV vaccination program is not directly correlated to the level of awareness of vaccinated women. Based on the results of other studies, it was concluded that women who were vaccinated against cervical cancer did not have a higher level of knowledge about the HPV, than the non-vaccinated ones, although it would be expected that vaccinated women would have received at least basic information on the virus and its implications [41, 42]. Similarly, Fishman and his colleagues noticed that neither parental nor adolescent HPV knowledge was related to future adolescent vaccination, as some participants with a low level of awareness about the HPV and its preventive vaccination, eventually completed the prophylactic vaccination program, whereas, in contrast, individuals who initially demonstrated high levels of knowledge, were eventually not vaccinated against HPV and cervical cancer .