The prevalence of the oncogenic HPV-types increases as with increased severity of dysplasia
We first studied the prevalence of different HPV-risk-types among women divided into the LSIL and HSIL dysplasia groups. In total, 45.0% (36 cases) of the women with LSIL (n = 80) were infected by oHPV-types and 10.0% (eight cases) by non oHPV-types. Only one woman in the LSIL group had exclusively pro oHPV-types (1.3%), while 43.8% (35 cases) of the women in the group were HPV-negative (Fig. 1A). Notably, the group of women with HSIL (n = 90) showed the highest prevalence of the oHPV-types with 74.4% (67 cases) and the absence of non oHPV-types. Furthermore, this group presented two cases with pro-oHPV-types (2.2%), and 21 HPV-negative cases (23.3%) as shown in Fig. 1A. Moreover, when comparing oHPV-prevalence in the LSIL versus the HSIL group, significantly more cases of oHPV in the HSIL than in LSIL group were observed (p < 0.01) as shown in Fig. 1A. Further detailed subgrouping based on clinical data of women with HSIL demonstrated that the prevalence of oHPV-types continued to rise corresponding to an increase in the severity of dysplasia. Excluding the cervical cancer subgroup with low sample size (n = 2), 14, 19, and 33 cases of oHPV-types were found in moderate, moderate/cancer in situ, and cancer in situ subgroups, respectively, constituting 63.6%, 76.0%, and 80.5% of the total cases in the corresponding groups, respectively (Fig. 1B).
Oncogenic HPV-types are the most prevalent across all ages in women regardless stage of dysplasia
When assessing the prevalence of each HPV-type among the women in the study, we demonstrated that HPV16 was the most prevalent among all the HPV-types (24.1%, n = 41) followed by another two oHPV-types HPV52 (10.0%, n = 17) and 33 (7.1%, n = 12). The most prevalent non-oHPV-type was HPV42, which was found in 7.1% (n = 12) of women followed by HPV70 (2.9%, n = 5) and HPV43 and 44 (both 2.4%, n = 4) as shown in Fig. 2A.
We further investigated the prevalence of HPV-infection based on different age groups and found that the overall HPV-infection followed a similar trend as found in the oHPV-infection (Fig. 2B). The highest prevalence of any HPV-type was found in the youngest group aged 21–25 years old in which 91.7% (n = 33) of the women were infected with at least one type of HPV, and 74.4% (n = 29) were infected with one or more oHPV-types. The HPV-prevalence dropped gradually with ageing in individuals and reached the lowest prevalence among individuals aged 36–40 with 45.5% (n = 10) in women presenting any HPV-infection and 40.9% (n = 9) with at least one oHPV-type. The HPV-prevalence started to increase again after 40 years old and peaked 68.2% (n = 15) of any HPV-infection and 63.6% (n = 14) of any oHPV-type among women aged 50–70 years old (Fig. 2B).
Remarkably, when we examined the cases with available information on vaccination status in detail, the vaccinated individuals of the two youngest age groups, 21–25 and 26–30 years old, did not present oncogenic HPV-infection of the types included in the vaccine, while in unvaccinated women 60.0% (n = 6, 21–25 years old) and 33.3% (n = 4, 26–30 years old) of individuals were positive for the included types (Table 1). Furthermore, the youngest group of vaccinated individuals showed the highest number of oncogenic-HPV-infection of the types not included in the vaccine (70.0%, n = 7) as shown in Table 1.
Oncogenic HPV-types among vaccinated women with dysplasia was different compared to the unvaccinated women
To evaluate further the efficiency of the HPV-vaccine, we analysed the prevalence of HPV-types covered in the quadrivalent-vaccine (HPV6, 11, 16, and 18) in the groups with and without vaccination regardless of dysplasia stage. Less women were infected with HPV-types covered in the vaccine among the vaccinated women (n = 1) compared to the non-vaccinated women (n = 23). The majority of the vaccinated women were positive for the oncogenic-HPV-types not covered in the quadrivalent-vaccine. Besides, in the group of unvaccinated women, the percentage of individuals infected with HPV-vaccine -covered or -not-covered types were 35.4% (n = 23) and 33.8% (n = 22), respectively (Fig. 3A). Notably, HPV58 (n = 4) was the leading oHPV-type in the vaccinated group, while HPV16 (n = 18), 52 (n = 8), 18 (n = 5), and 39 (n = 5) were the most prevalent oHPV-types in the unvaccinated group (Fig. 3B).
Finally, to obtain a more detailed view of the HPV-types among vaccinated and unvaccinated women with different stages of dysplasia, we divided the vaccinated and unvaccinated groups into the LSIL and HSIL groups. In the LSIL group, a lower percentage of HPV-types not covered in the current vaccine was found in vaccinated women (36.4%, n = 4) versus unvaccinated women (53.8%, n = 14). However, the situation is different among women with HSIL dysplasia grade, in which the unvaccinated individuals presented a prevalence of 40.0% (n = 18) by the HPV-types covered in the vaccine and 26.7% (n = 12) by the HPV-types not covered in the vaccine. Remarkably, among unvaccinated women, significantly higher number of HPV-infections (p < 0.01) with HPV-vaccine-types were found in the HSIL group in contrast to the LSIL group (Fig. 3C).