Such dormant HPV infection could be reactivated by pregnancy or delivery and be detected as new infection. There are several limitations to the current study. First, there were no cervical samples collected during pregnancy. The value of taking such samples would be difficult to justify due to the potential risk of the procedure during pregnancy. Therefore, we were unable to assess the prevalence, incidence, and clearance of HPV infection during pregnancy.
It would be valuable to determine these parameters during the pregnancy versus before and after pregnancy. For instance, a lower HPV prevalence during pregnancy could be due to a lower infection rate if fewer sexual partners are encountered. Second, initially HPV-negative women with their first postresolution HPV-positive cervical sample could have been infected any time between the last test before pregnancy and the first postpartum test. They were all considered as incident cases with the infection occurring after pregnancy, even though sexual activity usually continues, but at a lower frequency, during the first 2 trimesters of pregnancy [ 30 , 33 ].
In that way, the postresolution incidence potentially could be overestimated. Interestingly, when the first postpartum test was made between 3 to 6 months after pregnancy, the measured incidence was higher and might correlate with the increased sexual activity that is known to occur at that time.
Still, relatively few women had their first postresolution cervical samples collected within the first 3 months after pregnancy. The incidence during the 3—6 months postresolution period thus could be overestimated if some of the incident cases who acquired HPV infection before this period only were detected then.
Smoking status was recorded at study enrollment, though women may have quit smoking at pregnancy detection, as advocated by their physician. This information was not captured and may have impacted the results, but is unlikely to change the conclusion of the analysis.
We used the available data from the control arms of studies that differed in population, design, and objectives. This heterogeneity reduced the sample size and the opportunity to confirm some potential risk factors of HPV infection. The results of this pooled analysis add to the current understanding about HPV prevalence and incidence around pregnancy.
Prevalence of HPV was similar before and after pregnancy, suggesting that despite an altered immune system, the risk of infection by HPV may not change significantly during pregnancy although we had no direct access to this information. Another finding was that HPV incidence in previously HPV-negative women was the highest in the second 3-month period after pregnancy. This may reflect the timing of resumption and frequency of sexual activities.
Supplementary materials are available at Open Forum Infectious Diseases online. Consisting of data provided by the authors to benefit the reader, the posted materials are not copyedited and are the sole responsibility of the authors, so questions or comments should be addressed to the corresponding author. Benjamin Lemaire coordinated manuscript development and editorial support. Author contributions. All authors participated in the design or implementation or analysis, interpretation of the study, and the development of this manuscript.
All authors had full access to the data and gave final approval before submission. Data availability. To request access to patient-level data and documents for this study, please submit an enquiry via www. Financial support. GlaxoSmithKline Biologicals SA funded this study and was involved in all stages of study conduct, including analysis of the data GSK study identifier: GlaxoSmithKline Biologicals SA also took in charge all costs associated with the development and publication of this manuscript.
Potential conflicts of interest. All authors are employees of the GSK group of companies. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed.
National Center for Biotechnology Information , U. Open Forum Infect Dis. Published online Dec 4. Author information Article notes Copyright and License information Disclaimer.
E-mail: moc. Received Jun 12; Accepted Nov This article has been corrected. See Open Forum Infect Dis. This article has been cited by other articles in PMC. Results Prevalence of high-risk oncogenic hr -HPV types was similar before and after pregnancy Conclusions Pregnancy could not be confirmed as a risk factor for HPV infection in this population despite an increased incidence detected 3—6 months after pregnancy resolution. Keywords: human papillomavirus, incidence, pregnancy, prevalence, risk factor.
Statistical Analyses We analyzed demographic and baseline characteristics with descriptive statistics. Table 1. Open in a separate window. Table 2. Table 3. Table 4. Table 5. References 1. The causal relation between human papillomavirus and cervical cancer. J Clin Pathol ; 55 — Int J Cancer ; :E— Human Papillomavirus and Related Diseases in the World. Published July 27, Accessed November 22, Trottier H, Franco EL.
Human papillomavirus and cervical cancer: burden of illness and basis for prevention. Am J Manag Care ; 12 :S— Moscicki AB. HPV infections in adolescents. Dis Markers ; 23 — Cervical carcinoma and reproductive factors: Collaborative reanalysis of individual data on 16 women with cervical carcinoma and 33 women without cervical carcinoma from 25 epidemiological studies.
But sometimes, HPV infections will last longer and can cause some cancers. HPV infections can cause cancers of the:. HPV vaccination can be started at age 9 years. Children who get the first dose before their 15 th birthday only need two doses. People who get the first dose on or after their 15 th birthday need three doses. Skip directly to site content Skip directly to page options Skip directly to A-Z link. Human Papillomavirus HPV. Section Navigation. Unlike the evident association between HPV infection and the previously cited cancers such as CC, the real implication of HPV in the development of prostatitis is very complex because other viral and bacterial pathogens including Epstein—Barr Virus EBV , Chlamydia tracomatis , and Propionibacterium acnes have significantly been identified in prostate cancer PC tissues.
The viral load and HPV prevalence in the same tissues are also low 66 , However, several studies have demonstrated a link between HPV infection and progression of prostatitis from benign cancerous states to malignant states, as HR-HPVs, present in benign prostate tissues, have been shown to immortalize prostate cells.
These studies used several biological tools on both samples malignant and benign from the same patients , particularly PCR and RNASeq targeting L1 gene, and E6 and E7 oncogenes, to demonstrate the presence of HPV 16, 18, 45, 47, 76, and , suggesting that although low in viral load, the hyper-expression of HR-HPV oncoproteins E7 in benign tissues is responsible for the development of malignant prostate cancer 66 , Likewise, several studies debate the implication of HPV in the occurrence of breast cancer BC 69 , However, despite data revealing a high prevalence of HPV in cancerous tissues 69 , the involvement of HPV as an etiological agent in the occurrence of BC remains inconclusive as for PC 70 , In summary, the presence of HR-HPVs in an organ or tissue susceptible to a tumor other than those with a direct link with HPV implies that HR-HPVs would be involved in cell immortalization, and therefore in the progression to malignant states in the tissue or organ involved.
Thus, the presence of HPV in mammary or prostatic tissues should not be considered a carcinogenesis etiological factor until proven otherwise but rather as a risk factor for aggravation of already established benign states toward metastatic states 66 , 68 , 70 , Data based on HPV genotypic epidemiology and the presence of disease clusters detailed herein would reinforce the implication of HR-HPVs as an aggravating factor, but not as an etiological factor.
Yet, in developing countries, including Latin America and the Caribbean, and SSA, the death rate due to these cancers, as for CC, is the highest 8 , 66 , Moreover, the mortality rate due to these cancers is high in developed regions with high vaccination coverage rates after Australia and a low HPV incidence, but where the PC and BC prevalence and incidence are the highest. This excludes HPV as a necessary etiological factor for these cancers but establishes it as an aggravating risk factor.
Moreover, co-infections with other pathogens 66 , 73 serve as aggravating factors for prostate cancers along with HR-HPVs in developing regions where the epidemiologic cluster is variably very high and where access to care is limited. Knowledge of the genotypic prevalence in a given continental region will facilitate policy-making for strengthening vaccination programs in these specific regions or, to a lesser extent, develop a new generation of broad-spectrum vaccines.
Strengthening vaccination programs or choosing the vaccine under the influence of the most prevalent genotypes will help reduce the health and socioeconomic burdens related to HPV infection Some HPV genotypes are present all over the world. Indeed, several studies have shown that the most common types are HR-HPVs, with genotypes 16, 18, 59, 45, 31, 33, 52, 58, 35, 39, 51, 56, and 53 mainly found in descending order of prevalence.
However, their prevalence differs by region Table 1 7 , 11 , 12 , 46 , For instance, the prevalence of HPV 66, which is classified as a high-risk genotype, is slightly higher in the underdeveloped regions, particularly in Africa in the case of CC Table 1.
Northern America is the region where HPV is genotypically the least diversified, while in Asia, this diversity is greater. Finally, there is no positive correlation between the distribution of the regional prevalence of HPV genotype and the burden of the associated diseases.
Rather, this HPV-related burden is associated with molecular and genetic characteristics of HPV, revealing a regional variability within HPV, which we describe hereafter. HPVs are 50—60 nm in diameter, non-enveloped, small double-stranded DNA viruses belonging to the Papillomaviridae family. The 72 capsomeres covering the virus are repetitions of pentameric monomers composed of five identical L1 proteins, anchoring one L2 protein Figure 1A Only one strand of the 7—8 kb circular genomic DNA encodes for the eight functional early E—E8 and two structural late L1 and L2 proteins 84 , and carries a non-coding region called the long terminal region LTR Figure 1B.
Structural representation of HPV and the L1 protein used as antigen in current vaccines. C shows the top core structure of each L1 monomer in the capsomer in different colors revealing the surface loops serving as epitopes for neutralizing antibodies in VLP-based vaccines. D,E show the surface conformation in different views top and side view , revealing each loop in different colors and some specific heparan-sulfate proteoglycan HSPG binding sites rich in lysine K.
Both variable and constant regions are clearly seen. The former is specific for the different HPV genotypes and constitutes the loops BC, DE, EF, FG, and HI, Figures 1C—E carrying the surface-specific antigenic epitopes 85 that interact with the host's membrane receptors during the cell entry process and are responsible for the production of neutralizing antibodies Despite their residual variability, these loops have an identical three-dimensional structure conserved within HPVs.
The latter is in the highly conserved regions within the same HPV types, with the same roles, including membrane receptor binding, L1—L1, L1—L2, and L1—L2 interactions 85 , 87 , This protein is the current subject of several studies on HPV therapy because of the presence of high-affinity domains with the host, responsible for stimulating the immune response 89 , and specifically its ability to self-assemble into highly immunogenic, non-infectious virus-like particles VLPs 87 , 90 , The immunogenic surface loops described as hypervariable regions of L1 protein play an important role in the existence of variability within HPV variants responsible for specific virulence or persistence risk for disease occurrence according to regions as described later.
The intratypic variability in association with the distribution of the HPV-associated burden is discussed in the discussion section.
Moreover, the naturally occurring variation within the L1 gene is also involved in the production of type-specific neutralizing monoclonal antibodies. Although the rate of mutations causing diversity in papillomavirus is low and slowed by the corrective activity of cellular DNA polymerases during viral replication 92 , 93 , there is nevertheless considerable genetic variability within papillomaviruses, especially in HPVs.
Phylogenetic tree of HPVs. This phylogeny reconstruction was based on the neighbor-joining method with bootstrap replications using MEGA7 software. It shows that all the oncogenic HPV types are clustered together within the same alpha gender.
The classification and genetic variability within HPV are based on the sequential parsimony identity of the viral genome. The existence of these natural intratypic molecular variants had been demonstrated years ago from comparisons of the LCR sequences of HPV, proving to be specific or more widespread in certain parts of the world This statement, based solely on studies of HPV 16 isolates, could be generalized to all papillomaviruses 80 , 96 — , as a similar description was established for the inter-population variability found in HPV 18, 33, and 45 76 , 77 , , This inter-population variability made it possible to explain that HPVs from the same type induce different gene expression profiles associated with a certain disease occurrence risk, and thus to understand why in some regions the burden of HPV-associated diseases is higher than in others, for the same variants, as presented previously Therefore, whether the currently available vaccines are in terms of immunogenicity equally effective on all existing HPV intratypic molecular variants is uncertain, particularly on the prevalent variants in low- and middle-income countries.
From the available data, the existence of intratypic molecular variants from L1 proteins, specifically from the surface loop sequences, could now explain in part why VLP-based HPV vaccines have variable efficacy or efficiency across the world. In other words, the high prevalence of HPV-associated burden observed in some parts of the world might be due to the low efficacy of the current VLP-based vaccines.
Most studies describing the HPV infection cycle were conducted on a few viral strains, including HPV 16, 18, and 31 However, despite the genetic variability and the related-diversified infection profile, the infection mechanism remains similar Figure 3. In rare cases, particularly in the uterine mucosa, the virus can reach the targets directly through the transformation zone between the squamous epithelium of the ectocervix and the glandular epithelium of the endocervix without mucosal tissue damage Figure 3 HR-HPV infection cycle at the molecular level and progression to invasive cancer.
Left: HPVs enter either through a microlesion on the upper layer or directly through the squamocolumnar junction, infecting basal keratinocyte cells.
Sequential viral protein expression is shown green arrow according to the order of their synthesis throughout the productive infection. Once infected, cells can progress to a worse infection state characterized by viral DNA integration into genomic DNA and overexpression of E6 and E7 oncoproteins.
Right: virus—receptor interactions from the attachment to the internalization on the epithelial cells during one infection cell cycle. The virus entry into undifferentiated epithelial cells depends on specific molecular interactions involving the viral antigens and host receptors. In fact, structural studies of L1 revealed the presence of four heparan-sulfate proteoglycan HSPG —specific binding sites, rich in lysine K Figures 1D,E required for productive infection 86 , Once in the intraepithelial environment, the first binding between the L1 and the HSPG is established.
These bindings lead to the first cyclophilin B CyPB —dependent L1 protein 3D conformational change , releasing the N terminus end of L2 protein, which becomes exposed and vulnerable to the proteolytic action of furin, a cellular protease also known as protein convertase Through endocytosis, the virus is transported within the small vesicles to the nucleus through the ER and the Golgi, where a series of interactions and structural changes of the vesicles allow decapsidation and release of the viral genome near the nuclear membrane.
The episomal viral genome enters the nucleus through nuclear pores to initiate viral replication , HPV replication depends on epithelial cell differentiation. Indeed, by infecting undifferentiated basal cells, the virus guarantees its multiplication and persistence. Consistently, by dedifferentiating, the basal cells at the same time ensure viral protein synthesis sequentially, as presented in Figure 3 , thus ensuring viral multiplication latent or active and increasing the risk of HPV infection and related diseases beforehand.
Therefore, the L1 protein is the most important in the infection process viral entry. Owing to the presence of multiple surface epitopes, it possesses the ability to boost immunity against HPV by producing a high amount of specific and effective antibodies that recognize HPV in the physiological medium. Although the modalities of HPV infection are the same in general, as seen previously, the pattern of gene expression remains different, with differences in virulence 80 due to variability between variants based on L1 protein.
Thus, a good initiative in the process of eradicating HPV infection would be to develop vaccines specifically from L1 proteins for each region, given the divergence. In a normal cell cycle, basal epithelial cells divide asymmetrically to renew the basal layer on the one hand and the cutaneous or mucosal epithelium on the other hand. Thus, the number of divisions during cell differentiation remains limited to the formation of the apical epithelium.
In contrast, HR-HPV infection leads to the maintenance of this cell division, which is the long-term origin of the HPV-related diseases presented previously. At the molecular level, it is the hyper-expression of the E6 and E7 proteins, which leads to the maintenance of cell division. Indeed, studies have shown that the overexpression of E6 and E7 oncoproteins occurs as a result of the viral genome integration into the host genome, causing a loss of expression of some viral genome parts, including E2, that negatively regulates p97 — In the absence of E2 repression activity, p97 freely induces the expression of E6 and E7, which has compromising molecular implications , leading to increased risk of diseases, notably HPV-related cancers Figure 3 , , Clinically, after a primary infection, the manifestations of infection are not perceptible early; this makes acute HPV infection very poorly documented.
The anti-HPV antibody kinetics have not yet been determined because the prodromes associated with HPV acute infection occur very late after infection; however, studies are underway The duration of virus elimination 2. Women who experience viral clearance and have normal cervical cytology are at low risk 1. Persistence of HR-HPV infection, abnormal cytology, intercourse, and immune weakness have been reported to be some of the key factors in the development of ICC.
It should be noted that the persistence of the infection must be differentiated from reinfection after clearance, which presents a risk of developing CIN3 3. Whether this statement concerns reinfections with the same HPV strain as the initial infection or with different strains is unknown.
This figure is an adaptation of the recently published study findings The main characteristic of the CVM is its microbial diversity Lactobacillus spp. In this figure, and as previously found, the abundance of Lactobacilus spp. However, the progression of the infection to the precancerous lesions is associated with a subsequent increase in the microbiota variability, specifically Gardnerella vaginalis in red bacteria and some pathogenic fungi.
After the establishment of infection, replication is maintained by the E6 and E7 proteins, and HPV L1 protein plays only a minor role limited to the repeated binding with the neighboring cells.
Furthermore, it has been revealed that a significant correlation exists between the vaginal and cervix microbiota and the natural history of HPV infection Figure 4.
The vaginal microbiota consists of a variable bacterial population whose quantitative and qualitative changes have been associated with several gynecological disorders However, its pathophysiological role in the context of HPV infection was unknown until recently.
Usyk et al. In other words, they demonstrated the hypothesis raised earlier that increased bacterial diversity combined with depletion of Lactobacillus spp. In addition, they found that Gardnerella -type bacteria Gardnerella vaginalis , along with Mobiluncus sp. Specifically, the pathological effect of Gardnerella on the progression of lesions was positively mediated by an increase in microbial diversity.
Therefore, by monitoring the presence of Gardnerella in HPV-infected women with intraepithelial lesions and high bacterial diversity in CVM, it is possible to predict a possible risk of developing invasive cancer.
On the other hand, HPV-infected women with low-grade intraepithelial lesions and high abundance of Lactobacillus spp. So far, it is clear that vaccination is the first line of defense against HPV infection and related diseases.
Several studies aimed at reducing the virus-related disease burden led to the development of three currently available vaccines and several candidate vaccines at advanced clinical trial phases 90 , — These vaccines are Cervarix, Gardasil, and Gardasil9.
Gardasil, Cervarix, and Gardasil9 are highly effective vaccines approved in , , and , respectively, by the Food and Drug Administration , to prevent HPV infections and related diseases , , , Recently, Rossi et al. Importantly, according to WHO, none of these studies revealed any major adverse effects Thus, according to the prevalence and distribution of HPV across different regions of the world Table 1 , we can safely speculate that Gardasil9 alone could prevent up to All these vaccines are developed from HPV L1 proteins obtained into VLPs 90 , and therefore retain all the structural and immunogenic characteristics of the virion described hereinbefore Figure 1.
Because HPV vaccines act by inhibiting viral entry into cells, they become less effective when an infection is already established, and offer limited protection against reinfection or self-infection. Thus, in some countries, their acceptance and introduction into immunization programs have been followed by a waning of infection rate, like in Australia, where vaccination coverage is the highest worldwide Similarly, in regions where 9vHPV is already accepted, a significant waning of HPV-related burden is expected because recently, the vaccination age group has been widened for both sexes from under 9 to almost 50 years old However, the cost of vaccination remains a real obstacle, particularly in low- and middle-income countries, justifying the huge burden of HPV infection.
However, knowing that HPV can also cause penile and anal cancers, it is questionable whether HPV testing of cervix, urine, or feces is appropriate to predict the occurrence of penile and anal cancers in men and women. Furthermore, as stated in section Cervicovaginal Microbiome and Precancerous Lesion Occurrence RISKS, it is now known that the CVM is implicated in the natural history of HPV infection, and the monitoring of bacterial variation in the CVM is now a novel and effective measure in the follow-up diagnosis of HPV-infected women and could help to identify women at risk of developing cancer.
This knowledge could help in the prevention of HPV infection and related diseases. Despite all these control strategies, particularly vaccination, there are still high rates of morbidity due to HPV and related diseases in certain regions of the world because of challenges encountered.
Regarding the first case, in certain regions, vaccine coverage assessment studies showed that the vaccination programs are not adequately completed in many patients who received at least one 1 dose , , mainly because of poor follow-up and high vaccine costs. To deal with this, it is recommended that governments should provide almost-free or half-cost vaccination programs, as it can increase vaccination coverage , In addition, studies on the impact of vaccination programs in Australia and Scotland showed that two-dose programs or better one-dose programs might be adopted as they are less expensive and seem more effective than the three-dose programs , , However, the effective duration of immunization and the ability to prevent the occurrence of HPV-associated cancers remain an important issue.
Moreover, vaccine development systems insect cells and yeast are expensive; thus, next-generation vaccines based on cost-effective systems are needed. In many countries, ignorance of the susceptibility to HPV infection and associated disorders, and the lack of confidence in vaccination programs are some of the major challenges leading to a refusal of parents to vaccinate their children , Sensitization modules in immunization programs could greatly improve immunization coverage rates in areas where vaccination programs have already been instituted This lack of confidence in the HPV-vaccine explains their refusal in certain countries, such as China.
In fact, concerning the probable side effects in the Chinese population, as no clinical trial had reported the same vaccine safety profile as observed elsewhere, the Chinese government delayed their approval.
In , these vaccines were approved , demonstrating their effectiveness and safety , , However, vaccination coverage remained low, and the HPV-associated burden was still high in this area. Finally, it is worthy of note that the high burden of HPV is also associated with the antigenic protection limits of current vaccines. Among the 17 HR-HPVs 16, 18, 31, 33, 35, 39, 45, 51, 52, 53, 56, 58, 59, 66, 68, 73, 82 , these vaccines can only protect against 7 16, 18, 31, 33, 45, 52, and 58 , offering Furthermore, the current vaccines contain Caucasian HPV genotypes and are very effective in these populations.
Therefore, further broad-spectrum and specific vaccines are required. Precisely, the major preventive strategies against HPV and related diseases, including vaccination and diagnosis, are the same worldwide.
These strategies would be effective only if the molecular and genetic characteristics of HPV, already revealed and well-described here, were the same all over the world. For instance, as discussed here, the HPV infection profile and related burden are strongly associated with the regional variability in HPV genetic features, which therefore explains the prevalence distribution. Taken together, the preventive strategies should be redirected to the specific regional features of HPV L1 protein used in developing vaccines.
While HPV is widely spread, the related infection and its incidence as well as the burden of the related diseases differ considerably by and within regions according to several factors, including both extrinsic geographical region, socioeconomic development, culture, and molecular variability of viral genome and intrinsic lifestyle, age, gender, affected anatomic site, and health state factors 9.
HPV is ranked as the second most common pathogen leading to gynecological disorders and the first to cause female cancers. CC, which is the second most common cancer after breast cancer and the third most prevalent cancer in women 3 , 7 , is the most common disease resulting from infection with the 17 known HR-HPVs 16, 18, 31, 33, 35, 39, 45, 51, 52, 53, 56, 58, 59, 66, 68, 73, 82 , followed by anal, vulvar, penile, vaginal, and upper aerodigestive cancers.
Other HPV-associated diseases include anogenital and cutaneous warts. HPV implication in PC and BC, although inconclusive, shows its participation in cell immortalization, which is responsible for cancers.
With the dynamics of transmission 21 , the consequences in men living in these countries would be similar to populations in developed countries. Most of these countries are characterized by poor quality of life, particularly with limited access to basic needs such as healthy food, drinking water, decent housing, good hygiene, and medical care Due to extreme poverty, even the young women engage in unsafe sexual practices such as prostitution to satisfy their basic needs 16 , 26 , 27 , consequently increasing the risk of infection.
The young women, thus very little educated, are used unconsciously as a currency to feed the poor family. Overall, this first explains why the HPV-related burden is higher in these regions. Furthermore, the high prevalence of other viral and bacterial diseases epidemiologic cluster increases the burden associated with HPV infection and HPV-associated diseases in developing countries. More interestingly, it has recently been shown that the CVM plays a very important role in the progression of infection toward the development of precancerous lesions, and therefore in the natural history of HPV infection.
High variability in the cervicovaginal microbial population associated with depletion of Lactobacillus spp. It is noteworthy that limited access to healthy living conditions, potable water, good hygiene, and mainly medical care associated with the high prevalence of other gynecological infectious diseases in most of these regions, especially in Africa 29 , lead to high variability in the CVM, particularly associated with the development of vaginal dysbiosis and bacterial vaginosis.
These vaginal affections, defined as a highly diverse CVM containing a small amount of Lactobacillus spp. From an HPV molecular genetics perspective, this uneven distribution of HPV-associated burden across the world is a rigorous and rational explanation. The major HPV viral capsid proteins L1 protein are the most important in the early stages of infection and the reinfection process during viral persistence, and are therefore mainly responsible for the activation of the immune response Figure 3.
They are used as vaccine antigens to prevent HPV infections and the occurrence of associated diseases. Figure 2 94 , 95 , there is a non-negligible variability within variants of identical HPV types but from distinct regions 80 , 96 , 96 — , which can be observed in the same geographic region due to human migration , This existing polymorphism within variants of the HPV L1 genes plays an important role in type-specific recognition and neutralization, in the associated virulence or oncogenicity, and in the structure of the viral capsid.
In their study, Gurgel et al. This huge variation has an impact on oncogenic potential. In addition to studies based on L1 genes and their roles, this effect has also been demonstrated in the LCR genes and some early proteins E involved in viral functions 76 , 77 , 80 , 96 — Taken together, this polymorphic variability and the associated oncogenic potential positively correlate with the distribution data of HPV-associated disease burden and thus explains why the HPV-related burden is higher in developing regions.
The current preventive strategies, which include diagnostics and vaccination programs with the current HPV vaccines 2-, 4-, and 9-valent vaccines and, in particular, the difficulties linked to their implementation in certain regions, is another aspect that explains the uneven distribution of HPV-associated diseases, specifically found to be higher in less developed regions.
Developed regions, including Australia, Europe, and America, where at least two of the three current HPV vaccines have been introduced, have reported a decrease in the incidence of HPV-related HPV infections, along with an absence of adverse effects 49 , , — The success of the vaccination program lies in the fact that in these developed countries, the HPV-related disease diagnosis rate has increased, access to health care is easier, vaccination programs are well-followed until completion, and the L1 protein used in the vaccines is from Caucasian intratypic variants.
However, in other regions, including China, SSA, and Latin America and the Caribbean, vaccination program implementation faces some limitations, partly accounting for the observed high morbidity due to HPV infection and HPV infection—associated diseases.
Given that the current vaccines are developed from non-African variants, it could be speculated that these vaccines have a limited effect on the African intratypic molecular variants, positively correlating with the high HPV-related burdens.
Additional studies highlighting this hypothesis would make it possible to reconsider the specificity of variants in the development of new vaccines. HPV is a common sexually transmitted infection worldwide, which disrupts normal social life and has lethal consequences. Apart from a few exceptions, the burden of HPV infection and related diseases remains high in developing countries, and factors that explain these high rates include poor living conditions, co-infections with other pathogens, poor healthcare facilities, and high cost of vaccines.
The high CVM variability caused by multiple genital infections, associated with high abundance of G. Moreover, the limited action of the current vaccine against the African intratypic variants prevalent in these regions explains the observed HPV burden because the current vaccines are not developed from these specific L1 variants, but general or Caucasians strains.
Therefore, even though the current vaccines have demonstrated satisfactory efficacy and safety, and even if the future expectations for the 9-valent vaccine seem satisfactory, the need to develop broad-spectrum vaccines targeting other HR-HPV variants and next-generation vaccines targeting other HPV proteins remains existential. Furthermore, the adoption of one- or two-dose vaccination programs is highly desirable, as it will reduce the cost and allow broad coverage , , Awareness programs and the budget strengthened toward immunization would be beneficial in limiting recrudescence in women and lowering the burden of infections in so-called reservoirs men and women.
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