The present study shows that knowledge about HPV and cervical cancer is low for Ouro Preto’s adolescent girls and their mothers/guardians. However, based upon the percentage of correct answers, it was observed that, as expected, mothers/guardians had more knowledge than adolescent girls. Sociodemographic factors, such as age, educational level, and household income interfered in the grade of knowledge of the participants about the subject. HPV immunization dropout rate was high (32.3%), but there was no association with low knowledge.
Most of the participants were unaware of the causal relationship between HPV and cervical cancer or between HPV and the development of genital warts. In addition, adolescent girls and mothers/guardians did not know that HPV infection is common, and they had low knowledge about signs and symptoms, and the route of transmission of this infection. Similar results were found in a study that analyzed the knowledge of women in the city of Natal, capital of the northeastern state of Rio Grande do Norte, Brazil, in which few interviewees cited correctly the mode of transmission of HPV, the signs and symptoms of virus infection, and correlated HPV infection with the occurrence of cervical lesions . In contrast, 74.1% of adolescent girls and 67.6% of their mothers in Hong Kong correlated HPV infection with cervical cancer .
In our sample, higher knowledge was observed concerning the broader concept of vaccine and, consequently, its prophylactic purpose. However, participants had a superficial knowledge about the specifics of the HPV vaccine, such as the recommended age group for vaccination, and number and interval between doses, which was also evidenced in other studies [17, 22]. Moreover, 11.6% of adolescent girls understood that prevention of HPV infection was restricted to vaccination. This appreciation of HPV vaccine may be a reflection of nationwide immunization campaign, and also of confidence of the Brazilian in the efficacy of immunobiologicals. It is known that frequent use of condoms is associated with decreased rates of HPV infection as well as other STIs . However, few adolescent girls (12%) in this study considered condom use as primary method of HPV prevention. Therefore, vaccine may generate a false sense of complete protection by reducing care that leads to HPV prevention.
Another important topic in HPV prevention and cervical cancer control is the Pap smear. Among mothers in this study, approximately 95% reported having had the test at least once in their lifetime. Differently, Lima et al.  showed 87% coverage of the Pap smear in a study involving women in the city of Natal, Rio Grande do Norte, Brazil. In the same study, 69.4% of women performed Pap smear with a frequency of at least once every three years, as recommended in Brazil, which was lower than mothers rate of the present study (72.6%), who reported performing the test annually. In Brazil, in general, there is no organized screening program; thus, opportunistic testing predominates, in which while some women go without screening others are over-screened, as occurred with the mothers in our study. To improve the cost-benefit ratio, while increasing the coverage of the target population and decreasing cervical cancer rates, it is necessary proper implementation of early detection of cervical cancer strategies as indicated by the Brazilian Guidelines for Cervical Cancer Screening . Regarding knowledge about cervical cancer screening, results showed that the most of mothers/guardians (79.9%) interviewed the current study in Ouro Preto had a higher level of knowledge than women of the city of Natal, as only 47% of Natal’s women had medium or high level of knowledge about Pap smear . Although mothers/guardians recognize the importance of Pap smear to prevent cervical cancer, the fact that participants do not associate HPV infection with the development of cervical lesions may be a barrier to reduce cases of this neoplasm. Thus, there is a need to reinforce the relevance of Pap smear for early detection of cervical lesions.
Several socioeconomic, demographic, and behavioral factors may interfere with the knowledge about HPV and cervical cancer [23, 31, 34]. Having higher education, and higher household income had a positive influence on the knowledge. Indeed, we observed that older adolescents attending more advanced school levels and mothers holding a university degree and higher family income had better knowledge regarding HPV infection and prevention. These results corroborate Abreu et al., who showed that participants who reported high knowledge about HPV had a higher level of schooling and average family income (p < 0.001) . Individuals with higher socioeconomic status possibly have more access to information, and consequently could be more aware regarding HPV infection and prevention measures [21, 23, 34, 35]. The main source of information cited by participants in our study was television/radio. However, such media is not considered the most appropriate or it is not enough to improve knowledge and lead to prevention behavior [35, 36]. Moreover, low level of schooling can make it difficult to understand the content transmitted by these or other sources of information [21, 35, 36]. In our sample, few participants reported that they obtained information about the HPV vaccine from health care providers. Previous studies have shown that health providers play a key role in improving the level of knowledge and acceptability of the HPV vaccine. Health care providers should promote communication about HPV infection and its prevention, and thus bring awareness on vaccine effectiveness [34, 36, 37].
Decreasing trends in HPV immunization uptake have been observed in Brazil. According to official data, from 2014 to early 2018, only 48.7% of adolescent girls aged 9 to 14 years completed a two-dose schedule . This coverage rate is below the 80% goal recommended by the Brazilian Ministry of Health for HPV vaccination . In this study, only 65.5% of adolescent girls adhered to HPV vaccination. Previous research described that adequate knowledge about HPV infection and awareness of prevention against this virus result in higher vaccine acceptance rates [18, 21, 23]. However, in our study, HPV knowledge was not associated with vaccine uptake. This may have occurred because a significant portion of participants presented important knowledge deficiencies on the subject. Thus, both adolescent girls who completed the vaccination schedule, and those who did not complete had low knowledge regarding HPV infection. In 2016, a study conducted in the northern state of Roraima, Brazil, showed a relatively high rate of non-adherence to HPV vaccination (17.3%). The authors reported that the lack of HPV knowledge negatively influenced the acceptance of HPV vaccine by parents/guardians of girls . Other studies reported that mothers/guardians play a key role in the decision-making regarding vaccination uptake [23, 38,39,40]. Thus, there is a clear need for the optimization and qualification of the information that will be transmitted to the population regarding HPV and cervical cancer. Additional improvements in public health strategies for HPV vaccine and cervical cancer should include educational interventions tailored to different audiences with the support of health care professionals and teachers. These are considered to be potentially influential groups to promote the increase of HPV vaccine uptake [18, 19, 38, 41].
This study was conducted in a small town, so caution should be exercised in generalizing the findings to other locations. However, the number of adolescent girls and mothers/guardians interviewed was high and recruitment occurred in both urban and rural areas. In addition, it is a region with a large movement of people and the results of this study are corroborated by similar research conducted in Brazil and in other countries. Thus, the data obtained herein may guide public health actions aimed to prevent HPV infection in places with a similar population profile.
Considering that a wide interval was used to define “high knowledge”, both adolescent girls and their mothers/guardians have reached a very low knowledge score. Thus, this study points to the need of implementing educational initiatives on HPV and cervical cancer. For guarantee the effectiveness of educational interventions, it is essential to look at socio-cultural diversities, the ability of understanding, and access to information of each population group [21, 34]. Furthermore, the combination of different means of communication especially schools, health care providers, and social networks, has been shown to be effective in increasing the understanding HPV infection and vaccine and induce changes of individual behaviors [36, 42].