Higher prevalence of human papillomavirus infection in adolescent and young adult girls belonging to different Indian tribes with varied socio-sexual lifestyle

Implementation strategies of cervical cancer screening in South Asia: A systematic review

BACKGROUND

Cervical cancer is a preventable cancer by screening, vaccination and timely management of preinvasive cervical lesions. However, about 90% of the global burden of cervical cancer is reported from developing countries.

OBJECTIVE

This systematic review aimed to analyze the strategies implemented for cervical cancer screening in South Asia.

SEARCH STRATEGY

An electronic search of PubMed/MEDLINE, Scopus and Google Scholar was carried out for articles published in English, evaluating the implementation of cervical cancer screening between December 2000 and June 2023 in South Asia using appropriate search terms.

SELECTION CRITERIA

Cross-sectional studies, randomized control trials (RCTs) or non-randomized controlled trials evaluating different cervical screening strategies were included.

DATA COLLECTION AND ANALYSIS

A three-stage selection process was performed using a validated proforma including the title, author, year of publication, objective, country, study design, screening methods, strategies and outcomes, and results. The systematic review was designed based on Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The risk of bias was evaluated with the National Heart, Lung, and Blood Institute's (NHLBI) Quality Assessment Tools.

MAIN RESULTS

Out of the initial 1135 articles reviewed systematically, 23 studies met the inclusion criteria and were included in the qualitative synthesis of results. The implementation outcomes measured were acceptability (n = 23 100%), feasibility (n = 22, 95.7%), fidelity (n = 14, 60.9%), sustainability (n = 7, 30.4%), coverage (n = 4, 17.4%) and cost (n = 1, 4.3%).

CONCLUSION

Cervical cancer screening can be effectively implemented by restructuring the ongoing programs.

Prevalence and Type of HPV Genital Infection in Girls: A Systematic Review and Meta-Analysis

OBJECTIVES

This investigation explored the prevalence of human papillomavirus (HPV) infection by subtypes in girls aged up to 12.

METHODS

Four indexed databases, PubMed, EMBASE, Cochrane, and LILACS, were evaluated. Twenty-nine observational studies published between 1992 and 2018 were included.

RESULTS

The prevalence of genital condyloma acuminatum or HPV-positive serology due to prior infection among girls with suspected/confirmed sexual abuse was 25%, and without a history or information about abuse, 8%. The analysis indicated that low-risk HPV types were the most prevalent among this group, corresponding to 86.6% of the identified types. Human papillomavirus 6 and 11 were the most prevalent types, followed by HPV 16 and 2. Moreover, the analysis identified limited epidemiological data on genital warts in children up to 12 years. Several studies focused on convenience sampling, sexually abused girls, or failed to separate data by gender.

CONCLUSION

Findings of our systematic review and prevalence meta-analysis indicate that the occurrence of HPV infection in girls aged 12 or younger is relatively rare, underscoring the significance of understanding the prevalence of HPV in the pediatric population. However, it is essential to be cautious when applying these results to the pediatric population, given cases of girls who are suspected of or have suffered sexual abuse. There is a pressing need for further research to fill the information gap on HPV infection in this vulnerable group.

A population based study on human papillomavirus infection and associated risk factors among women of the remote South Andaman Island, India

BACKGROUND

Human papillomavirus (HPV) is associated with cervical cancer and cervical dysplasia worldwide. Data on HPV prevalence in a region is important because it serves as a predictor of the likelihood of the population in that particular region acquiring cervical cancer. Moreover, with the availability of effective vaccines, the public health system must be aware of the preponderance of HPV to implement the vaccine. The present study was designed to understand the prevalence of HPV and associated factors among the women of South Andaman Island.

METHODS

A cross-sectional study was conducted among married women of reproductive age (18-59 years) from South Andaman District from 2018 to 2022. Cervical scrapes were collected from participants after obtaining informed written consent for HPV molecular testing (HPV DNA) such as PCR assay. Demographic data was collected using a standard questionnaire and statistical analyses were performed to determine the associated factors.

RESULTS

The study showed prevalence of HPV as 5.9%(95% CI: 3.9-7.9) and prevalence of HR-HPV16 was 4.1% (95% CI 2.6 - 5.5) and HR-HPV18 prevalence was 1.8(95% CI: 0.6-3). The independent factors associated the HPV positivity were age above 55 years, menopause, post-menopausal bleeding, blood-stained vaginal discharge and loss of weight. Age was associated with all HPV infections among the South Andaman women.

CONCLUSIONS

HPV 16 was reported as the predominant high risk HPV type circulating among women of South Andaman. Cervical cancer and precancerous lesions were significantly associated with HPV positivity and High risk HPV 16. Based on the knowledge of the risk factors associated with HPV, implementation of stronger public health awareness and prophylactic HPV vaccination is crucial among the women of this remote island.

Protocol for the formative phase of a trial (SHE-CAN) to test co-designed implementation strategies for HPV-based cervical screening among vulnerable women in two diverse settings in India

BACKGROUND

In view of the WHO's call for the elimination of cervical cancer as a public health problem, and current low screening coverage, Indian policy makers need evidence on how to effectively implement cervical screening programmes, ensuring equity in access. Our study will follow the INSPIRE implementation framework to co-design and test HPV-based screening approaches in two states of India with different health system organisation, based on understanding the status of screening as currently implemented, readiness and challenges to transition to HPV-based screening, and preferences of key stakeholders. Here, we describe our protocol for the formative phase of the study (SHE-CAN).

METHODS

The study population includes women from vulnerable populations, defined as residents of tribal areas, rural villages, and urban slums, in the states of Mizoram and Tamil Nadu. The baseline assessment will use mixed methods research, with desktop reviews, qualitative studies, and surveys. A capacity assessment survey of screening and treatment facilities will be done, followed by interviews with healthcare providers, programme managers, and community health workers. Interviews will be conducted with previously screened women and focus group discussions with under and never-screened women and community members. Stakeholder workshops will be held in each state to co-design the approaches to delivering HPV-based screening among 30-49-year-old women.

DISCUSSION

The quality and outcomes of existing screening services, readiness to transition to HPV-based screening, challenges in providing and participating in the cervical cancer care continuum, and acceptability of screening and treatment approaches will be examined. The knowledge gained about the current system, as well as recognition of actions to be taken, will inform a stakeholder workshop to co-design and evaluate implementation approaches for HPV-based screening through a cluster randomised implementation trial.

Prevalence of vaginal HPV infection among adolescent and early adult girls in Jos, North-Central Nigeria

Purpose

Knowledge of the prevalence of HPV infection among adolescent and early adult girls is essential to determining the best age for the introduction of HPV vaccine, monitoring vaccine efficacy, and giving insight into determinants of persistent high-risk HPV infection, a necessary cause of cervical cancer. Yet, there have been limited studies of HPV infection among adolescent and early adult girls in low-and-middle-income countries.

Methods

In this cross-sectional study, we randomly selected 205 girls, aged 9–20 years, from 10 schools in central Nigeria. We obtained informed consent and assent, collected data, and trained participants to self-collect vaginal samples using swab stick. We genotyped HPV using SPF₁₀-DEIA/LiPA₂₅ and analyzed data using Stata 14®.

Results

The mean (SD) age of the girls was 14.9 (2.3) years. We found HPV in 13.2% of vaginal swabs. The earliest age at which anyHPV and hrHPV infections were detected was 10 and 12 years respectively. The prevalence of any HPV peaked at 16 and 17 years, hrHPV at 16 years, lrHPV at 17 and 18 years and multiple hrHPV 18 years of age. The prevalence of hrHPV infection was 1.5% among the 9–12 years age group, 2.9% among 13–16 years and 3.4% among 17–20 years old. The commonest hrHPV types detected were 52 (3.9%), 18 (1.5%) and 51 (2.4%). The most common lrHPV types was 6 (2.9%).

Conclusion

The prevalence of HPV infection in these urbanized young girls in Nigeria is high and commences after 9 years of age. HPV vaccination in this population should start at 9 years of age or younger to prevent the establishment of persistent HPV infection.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-022-07215-7.

The prevalence of HPV was 13.2% among adolescent girls in Jos, North-Central Nigeria.

The earliest age at vaginal HPV infection was 11 years of age.

The most predominant hrHPV type in vaginal swab was HPV 52.

These findings point to the need for introduction of HPV vaccine starting at 9 years of age among girls in Nigeria to give maximum protection.

Determination and evaluation of HR-HPV genotype in different communities of Bihar, India

OBJECTIVE

Human papillomavirus (HPV)-associated uteri cervix carcinoma continues to be the 2^nd highest cause of death among women in India. This study aims to identify the mode of HPV transmission in different communities such as Hindu, Muslim, Christian and Banjaran women of Bihar, India. Different patterns of life and cultural variations exist among Muslims, Hindus, Christians, and Banjarans. For example, Muslim wash their genital parts after urination and maintain genital hygiene, whereas Banjaran tribes, Christians, and Hindu communities do not maintain hygiene. Thus, the present study was undertaken to evaluate high-risk HPV (HR-HPV) infection among healthy women. We access to genuine reason for the cause of HPV transmission in women.

METHODS

Ethical clearance was obtained from MCS and RC Patna, India. A total 154 urine samples have been used for the detection of HR-HPV through a real-time PCR technique. The DNA extraction was done from collected non-invasive urine samples. The estimation and purification of DNA purity was performed by QuantiFluor^® dsDNA system and detected HPV-16 and HPV-18.

RESULTS

Overall, the prevalence of HR-HPV infection was detected to be 12.34% (19/154) whereas HPV-16 was found to be 9.9% (14/154) and HPV-18 was found to be 3.25% (5/154) in women. The lowest (2%; 1/50) prevalence of HR-HPV was observed in the Muslim community, while higher (25%, 16%, and 14.71%) prevalence was found in the Banjaran, Christian, and Hindu communities, respectively.

CONCLUSION

Our study indicates that personal hygiene possibly reduces HPV infection in women and the evidence suggests that male circumcision has a protective role of HPV infection in Muslim community. Therefore, personal hygiene and circumcision may reduce the risk of HPV acquisition and transmission as well as cervical cancer development in women.

The influence of IL1RN VNTR polymorphism on HPV infection among some tribal communities

Persistent infection of human Papillomavirus is the main etiological factor for cervical cancer. Austro-Asiatic tribes are early settlers in India and they have unique genetic variations compared to other people. The immunological response is crucial for the prevention of viral associated diseases. Interleukin-1 receptor antagonist (IL-1RN) is considered being an important regulator of host immune surveillance. A total of 45 Santali tribal women and 10 Kora tribal women were enrolled in the present study and demographic variables were recorded during collection. Genomic DNA was extracted from cervical/vaginal swab samples. IL1RN variable number of tandem repeats (VNTR) polymorphisms and HPV types were determined by PCR-based assay. Association between IL1RN VNTR polymorphisms with the HPV infections among the tribal communities was determined by logistic regression analysis. HPV18 prevalence was significantly higher among tribal women. We observed that the polymorphism A2*A2 (p = 0.022; odds ratio [OR] (95% confidence interval [CI]) = 0.16 (0.03-0.86)] were more resistant to oncogenic HPV infection. Use of oral contraceptives was associated with higher relative risk (p = 0.008; OR [95% CI] = 5.39 [1.47-19.8]) for oncogenic HPV18 positivity among the tribal women. The A2 allele homozygosity of IL1RN VNTR was identified to be associated with the protection from oncogenic HPV infection among various tribal communities of West Bengal and therefore may be a useful marker of host immune response among them.

Acquisition, prevalence and clearance of type-specific human papillomavirus infections in young sexually active Indian women: A community-based multicentric cohort study

In context of the ongoing multi-centric HPV vaccine study in India, unvaccinated married women (N = 1484) aged 18-23 years were recruited in 2012-2015 as age-matched controls to the vaccinated women and followed up yearly. We assess type-specific prevalence, natural history and potential determinants of human papillomavirus (HPV) infection in these unvaccinated women. Cervical samples were collected yearly for at least four consecutive years. A Multiplex Type-Specific E7-Based polymerase chain reaction assay was used to detect 21 HPV types. HPV prevalence was 36.4% during 6 years. Most common HPV types were 16 (6.5%) and 31 (6.1%). Highest persistence were observed for HPV 35 (62.5%) and 52 (25%). New HPV acquisition rate was 5.6/1000 person-months of observation (PMO), highest for HPV 16 (1.1/1000 PMO). Type-specific clearance rates ranged between 2.9-5.5/100 PMO. HPV 16 and/or 18 infections were 41% (95% CI 4-63%) lower among women with 2-<3 years between marriage and first cervical sample collection compared to those with <2 years. HPV prevalence and acquisition rates in young Indian women were lower than their Western counterparts. HPV 16 infections being most common shows the importance and potential impact of HPV vaccination in India. Women with 2-3 years exposure had reduced risk possibly due to higher infections clearance.

Cervical cancer screening in rural India: Status & current concepts

Cervical carcinoma is one of the most common and dreaded diseases of women, and in India, it accounts for 16 per cent of total cervical cancer cases occurring globally. The situation is more alarming in the rural areas where the majority of women are illiterate and ignorant about the hazards of cervical cancer. Different screening strategies such as rural cancer registries and camp approach for cancer detection have been found useful in minimizing the problem of cervical cancer in the villages. Various screening techniques such as visual inspection with acetic acid, visual inspection with Lugol's iodine, visual inspection with magnification devices-magnavisualizer, Pap smear and HPV-DNA testing have been suggested and tried under low-resource settings of our country, and cervical cytology screening has been found effective in reducing incidence of the disease. In the present review, feasibility of different screening methods has been assessed to find out the most suitable mode applicable at the rural level. Single lifetime screening particularly of high-risk women along with analysis of cost-effective tumour markers such as Argyrophilic nucleolar organizer regions (AgNOR) counts to discriminate high-risk dysplasia cases appears to be an appropriate approach in fighting against cervical cancer.

Human papilloma and other DNA virus infections of the cervix: A population based comparative study among tribal and general population in India

Background

Despite being preventable, cervical cancer remains a major health concern among women. Persistent Human Papillomavirus (HPV) and other viral co-infections may influence cervical dysplasia. We determined and compared the prevalence and risk factors of cervical viral infections among the tribal and general population of southern coastal Karnataka, India.

Methods

A population-based cross-sectional survey was conducted among 1140 and 1100 women from tribal and general population, respectively. Cervical infections with HPV, Epstein-Barr Virus (EBV), Cytomegalovirus (CMV) and Herpes-Simplex Virus (HSV) were examined using polymerase chain reactions (PCR) and DNA sequencing.

Results

HPV prevalence was higher among tribal women (40.6%) than general population (14.3%) while the prevalence of EBV (55.1%) and CMV (49.4%) were lower among tribal women than general population (74.3% and 77.5%, respectively). HSV infection was observed in tribal women only (1.8%). Among HR-HPV strains, HPV-18 was predominant among tribal population (28.3%) while, HPV-16 was predominant among the general population (9.1%). Infections were associated with age, educational status, unemployment and personal hygiene of tribal women. Phylogenetic analysis revealed that HPV-16 variants of tribal participants were closely related to non-European sublineages indicating greater risk of HPV persistence and carcinogenesis.

Conclusion

The study provides a comparative estimate for DNA virus infections of the cervix among women from general as well as tribal population in this region and also reveals a different type-specific pattern of viral infection. Further research is required to delineate the role of specific interactions between multiple virus infections and their role in carcinogenesis.

Prevalence and age-wise distribution of Human Papillomavirus type 16/18 infections among hospital screened women of a peri-urban area in West Bengal: Impact of socio-demographic factors

BACKGROUND

We undertook the current study on cervical Human Papillomavirus (HPV) prevalence along with cytology in women visiting the Gynecology Out-patient Department of a hospital for common gynecological ailments, subsequent to our earlier population-based study on HPV prevalence from India.

METHODS

We analyzed data on cervical-cytology (Pap smears) and PCR-based molecular detection of HPV infection along with socio-demographic variables (N = 696).

RESULTS

We identified 36.84% HPV-positive women amongst whom, HPV16 and 18 together predominated (79.37%) over other HPV types (20.63%). Contrarily, only 6.4% women revealed abnormal cytological lesions, of which, 46.51% were HPV-positive and 95% of such women harbored HPV16/18, while 5% harbored other HPV types. Individuals with normal cytology portrayed 36.09% HPV infections, of which, 77.97% were HPV16/18-positive and 22.03% harbored other HPV types. Overall HPV prevalence decreased significantly (p_trend  = 0.047) with increase in age, but HPV16/18 infections were significantly over-represented compared to the other HPV types across all age-groups. Specifically, HPV16 prevalence increased (p _trend < 0.01) with increase in severity of cervical lesions. HPV16 prevalence did not differ between the Hindus and Muslims but HPV18 was significantly higher among the cytologically normal Muslim women (24.14%, p = 0.02), compared to the Hindus (11.91%), specifically among those ≥ 30 years of age. There was a significant (p < 0.05) overrepresentation of HPV16 prevalence among women who were users of oral contraceptive-pills, irrespective of cytology.

CONCLUSIONS

Our study highlights the need for HPV16/18-based screening of cervical cancers in India considering the immense socio-cultural and genetic diversity at the population level.

Molecular characterization of lower vaginal swabs for Human papilloma virus in association with Chlamydia trachomatis infection in Cameroonian Women

Human papilloma virus (HPV) infection is an etiological factor for cervical cancer development and Chlamydia trachomatis (Ct) is considered as a cofactor. Understanding the dynamics of HPV and Ct infection could help to explain the incidence of early onset of cervical cancer (CC) observed in Cameroon. Lower vaginal swabs and sera from sexually active women were analyzed for HPV and Ct infection in association with risk factors. Questionnaires were used to document patients' lifestyle and risk factors. A total of 206 women participated in the study average 28.1±8years (16-50 years). HPV prevalence was 23.3% with subtypes 16 and 18 at respectively 2.9% and 1%. Ct infection totalised 40.8%, of which 23.8% were HPV- Ct co-infections. HPV infection was inversely associated with age (p=0.028). We found a positive association between Ct infection and the number of sex partners (p=0.012) and a negative association with parity (p=0.032). There was no significant association between HPV and Ct infections. High rates of HPV and Ct infections could be an indicator of cervical cancer risk in the near future. There is therefore an urgent need for sensitization as well as implementation of appropriate preventive measures.

Community-Based Prevalence of Genital Human Papilloma Virus (HPV) Infection: a Systematic Review and Meta-Analysis

Introduction:

Cervical cancer probably represents the best-studied human cancer caused by a viral infection and the causal association of this preventable cancer with human papilloma virus (HPV) is well established. Worldwide there is a scarcity of data regarding HPV prevalence with vast differences existing among populations.

Objective:

The aim of this meta-analysis was to determine the community-based HPV prevalence estimates among asymptomatic women from urban and rural set ups and in participants of cancer screening clinics.

Study design:

Systematic review and meta-analysis.

Methods:

PubMed-Medline, CINAHL, Scopus, and Google scholar were systematically searched for studies providing prevalence data for HPV infection among asymptomatic women between 1986 and 2016.

Results:

The final analysis included 32 studies comprising a population of 224,320 asymptomatic women. The overall pooled HPV prevalence was 11% (95% confidence interval (CI), 9%-12%). The pooled HPV prevalence of 11% (95% CI, 9%-11%) was observed among women attending cervical cancer screening clinics. The pooled HPV prevalences were 10% (95% CI 8%-12%) and 11% (95% CI 4%-18%) from urban and rural areas respectively, indicating higher infection rates among the rural women with the least access to cancer screening and cancer care.

Conclusion:

The prevalence rates in this systematic quantitative review provide a reliable estimate of the burden of HPV infection among asymptomatic women from developed as well as developing nations. Rural women and women attending cervical cancer screening programmes feature higher genital HPV prevalences compared to their urban counterparts.

Knowledge, Awareness and Attitude on HPV, HPV Vaccine and Cervical Cancer among the College Students in India

BACKGROUND

Infection of specific high risk Human papillomaviruses (HPVs) is known to cause cervical cancer and two prophylactic vaccines have been developed against two major high risk HPV types 16 and 18 for prevention of cervical cancer. Because of societal, religious and ethical issues associated with the vaccination of adolescent girls in India together with lack of awareness about HPV and HPV vaccines, no successful HPV immunization program has been employed in India.

OBJECTIVE

To determine knowledge, awareness and attitude of college students on HPV, HPV vaccine and cervical cancer.

METHOD

A questionnaire-based survey was conducted in a total of 1580 undergraduate students between the age group 16-26 years comprising 684 girls and 876 boys.

RESULTS

Out of a total of 1580 students, girls had more knowledge about cervical cancer (82.45%, p<0.001), HPV (45.61%, p<0.001) and HPV vaccines (44%, p<0.001) when compared to those in boys. However, knowledge about the types of HPV and vaccines was poor. Interestingly, students from biology-major had more knowledge and awareness about cervical cancer (81.89%, p<0.001) and HPV (46.58%, <0.001) when compared to non-biology students. Girls from both biology and non-biology group had higher awareness compared to boys. Analysis of odds ratio (ORs) along with 95% CI showed older girls with 1.2 to 3 fold (p<0.05) higher knowledge than boys. All students agreed that girls should get vaccinated against HPV (p<0.001).

CONCLUSION

It is suggested that there is a need for educational intervention and awareness campaigns to augment HPV immunization program for control of cervical cancer in India.

Urine testing to monitor the impact of HPV vaccination in Bhutan and Rwanda

Bhutan (2010) and Rwanda (2011) were the first countries in Asia and Africa to introduce national, primarily school-based, human papillomavirus (HPV) vaccination programmes. These target 12 year-old girls and initially included catch-up campaigns (13-18 year-olds in Bhutan and ninth school grade in Rwanda). In 2013, to obtain the earliest indicators of vaccine effectiveness, we performed two school-based HPV urine surveys; 973 female students (median age: 19 years, 5th-95th percentile: 18-22) were recruited in Bhutan and 912 (19 years, 17-20) in Rwanda. Participants self-collected a first-void urine sample using a validated protocol. HPV prevalence was obtained using two PCR assays that differ in sensitivity and type spectrum, namely GP5+/GP6+ and E7-MPG. 92% students in Bhutan and 43% in Rwanda reported to have been vaccinated (median vaccination age = 16, 5th-95th: 14-18). HPV positivity in urine was significantly associated with sexual activity measures. In Rwanda, HPV6/11/16/18 prevalence was lower in vaccinated than in unvaccinated students (prevalence ratio, PR = 0.12, 95% confidence interval, CI: 0.03-0.51 by GP5+/GP6+, and 0.45, CI: 0.23-0.90 by E7-MPG). For E7-MPG, cross-protection against 10 high-risk types phylogenetically related to HPV16 or 18 was of borderline significance (PR = 0.68; 95% CI: 0.45-1.01). In Bhutan, HPV6/11/16/18 prevalence by GP5+/GP6+ was lower in vaccinated than in unvaccinated students but CIs were broad. In conclusion, our study supports the feasibility of urine surveys to monitor HPV vaccination and quantifies the effectiveness of the quadrivalent vaccine in women vaccinated after pre-adolescence. Future similar surveys should detect increases in vaccine effectiveness if vaccination of 12 year-olds continues.

Complete Genome Sequences of Eight Human Papillomavirus Type 16 Asian American and European Variant Isolates from Cervical Biopsies and Lesions in Indian Women

Human papillomavirus type 16 (HPV16), a member of the Papillomaviridae family, is the primary etiological agent of cervical cancer. Here, we report the complete genome sequences of four HPV16 Asian American variants and four European variants, isolated from cervical biopsies and scrapings in India.

Immunogenicity and HPV infection after one, two, and three doses of quadrivalent HPV vaccine in girls in India: a multicentre prospective cohort study

BACKGROUND

An increase in worldwide HPV vaccination could be facilitated if fewer than three doses of vaccine are as effective as three doses. We originally aimed to compare the immunogenicity and frequency of persistent infection and cervical precancerous lesions caused by vaccine-targeted HPV after vaccination with two doses of quadrivalent vaccine on days 1 and 180 or later, with three doses on days 1, 60, and 180 or later, in a cluster-randomised trial. Suspension of the recruitment and vaccination due to events unrelated to our study meant that some enrolled girls could not be vaccinated and some vaccinated girls received fewer than the planned number of vaccinations by default. As a result, we re-analysed our data as an observational cohort study.

METHODS

Our study was designed to be done in nine locations (188 clusters) in India. Participants were unmarried girls aged 10-18 years vaccinated in four cohorts: girls who received three doses of vaccine on days 1, 60, and 180 or later, two doses on days 1 and 180 or later, two doses on days 1 and 60 by default, and one dose by default. The primary outcomes were immunogenicity in terms of L1 genotype-specific binding antibody titres, neutralising antibody titres, and antibody avidity after vaccination for the vaccine-targeted HPV types 16, 18, 6, and 11 and incident and persistent infections with these HPVs. Analysis was per actual number of vaccine doses received. This study is registered with ISRCTN, number ISRCTN98283094; and with ClinicalTrials.gov, number NCT00923702.

FINDINGS

Vaccination of eligible girls was initiated on Sept 1, 2009, and continued until April 8, 2010. Of 21 258 eligible girls identified at 188 clusters, 17 729 girls were recruited from 178 clusters before suspension. 4348 (25%) girls received three doses, 4979 (28%) received two doses on days 1 and 180 or later, 3452 (19%) received two doses at days 1 and 60, and 4950 (28%) received one dose. Immune response in the two-dose HPV vaccine group was non-inferior to the three-dose group (median fluorescence intensity ratio for HPV 16 1·12 [95% CI 1·02-1·23] and for HPV 18 1·04 [0·92-1·19]) at 7 months, but was inferior in the two-dose default (0·33 [0·29-0·38] for HPV 16 and 0·51 [0·43-0·59] for HPV 18) and one-dose default (0·09 [0·08-0·11] for HPV 16 and 0·12 [0·10-0·14] for HPV 18) groups at 18 months. The geometric mean avidity indices after fewer than three doses by design or default were non-inferior to those after three doses of vaccine. Fewer than three doses by design and default induced detectable concentrations of neutralising antibodies to all four vaccine-targeted HPV types, but at much lower concentration after one dose. Cervical samples from 2649 participants were tested and the frequency of incident HPV 16, 18, 6, and 11 infections was similar irrespective of the number of vaccine doses received. The testing of at least two samples from 838 participants showed that there was no persistent HPV 16 or 18 infections in any study group at a median follow-up of 4·7 years (IQR 4·2-5·1).

INTERPRETATION

Despite the limitations imposed by the suspension of the HPV vaccination, our findings lend support to the WHO recommendation of two doses, at least 6 months apart, for routine vaccination of young girls. The short-term protection afforded by one dose of HPV vaccine against persistent infection with HPV 16, 18, 6, and 11 is similar to that afforded by two or three doses of vaccine and merits further assessment.

FUNDING

Bill & Melinda Gates Foundation.