Publications by authors named "Kavita Panwar"

12 Publications

  • Page 1 of 1

HPV16 and HPV18 seropositivity and DNA detection among men who have sex with men: a cross-sectional study conducted in a sexual health clinic in London.

Sex Transm Infect 2021 Aug 23;97(5):382-386. Epub 2020 Dec 23.

Institute for Global Health, University College London, London, UK

Objectives: Men who have sex with men (MSM) have an increased risk of human papillomavirus (HPV) infection and related diseases compared with men who have sex exclusively with women. From April 2018, there has been a phased roll-out of HPV vaccination offered to MSM aged up to 45 years old who are attending sexual health clinics and HIV clinics in England. The vaccine is most effective if delivered prior to HPV infection. We estimated the proportion of MSM with no current vaccine-type infection and no serological evidence of prior infection, in a study undertaken prior to vaccine introduction.

Methods: We conducted a cross-sectional study among 484 MSM aged 18-40 years old who attended a sexual health clinic in London between 2010 and 2012. We estimated the prevalence of current and past infection by testing for HPV DNA in anogenital samples and for serum antibodies to HPV16 and HPV18.

Results: The median age was 30 years (IQR 25-35). The prevalence of HPV16 and HPV18 DNA was 13.2% and 6.2%, respectively. Seropositivity for HPV16 and HPV18 was 28.5% and 17.1%, respectively, with 11.4% seropositive for both types. Seropositivity for the same HPV type was strongly associated with anogenital DNA detection. 279 MSM (57.6%) tested negative for both HPV16 and HPV18 serology and were DNA negative for these two types; only 5 MSM (1.0%) were seropositive and DNA positive for both HPV types.

Conclusions: This is the first study to determine both the prevalence of HPV DNA in anogenital samples and HPV seroprevalence among MSM attending a sexual health clinic in the UK. Over half of MSM in this study had no evidence of a previous or current infection with either of the high-risk HPV types included in the quadrivalent vaccine, which supports the rationale for opportunistic HPV vaccination of MSM attending sexual health clinics.
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August 2021

Performance of human papillomavirus DNA detection in residual specimens taken for and nucleic acid amplification testing in men who have sex with men.

Sex Transm Infect 2020 Dec 16. Epub 2020 Dec 16.

Centre for Clinical Research in Infection and Sexual Health, University College London, London, UK.

Objectives: Rectal swab specimens, either alone or pooled with first-void urine (FVU) and pharyngeal swab specimens, are used to test for (CT) and (NG) infection in men who have sex with men (MSM). Following introduction of human papillomavirus (HPV) vaccination for MSM attending UK sexual health services (SHSs), HPV testing of residual CT/NG test specimens has been proposed to monitor HPV prevalence in this population. Performance of HPV detection in such specimens has not been evaluated previously.

Methods: MSM attending a UK SHS provided three specimens: (1) rectal swab for CT/NG, (2) pooled rectal/pharyngeal/FVU specimen for CT/NG and (3) dedicated anal swab for HPV. Specimen 3 and residual material from specimens 1 and 2 were tested for type-specific HPV DNA. HPV detection was by an in-house multiplex PCR and luminex-based genotyping assay.

Results: A total of 129 MSM were recruited with a mean age of 38.1 years; 24% were HIV-positive. Of the 129 MSM, 92 (71%) had any type-specific HPV DNA in ≥1 specimen; 80 (62%) had high risk (HR) HPV. Of 123 participants with sufficient residual pooled and dedicated specimens, 70 (56.9%) had detectable HPV on both, and 40 (32.5%) were negative on both; overall concordance was 89% (95% CI 83% to 94%), and kappa statistic was 0.78 (95% CI 0.66 to 0.89). Pooled samples had a 4.1% (95% CI -1.9% to 10.0%) higher test positivity rate than dedicated samples.Of 125 participants with sufficient residual rectal and specimens, 74 (59.2%) had detectable HPV on both, and 36 (28.8%) were negative on both; overall concordance was 88% (95% CI 81% to 93%), and kappa statistic was 0.74 (95% CI 0.61 to 0.86). Residual rectal samples had 5.6% (95%CI -0.6% to 11.8%) higher test positivity than dedicated samples.

Conclusions: We observed high concordance between the dedicated and residual STI test specimens. Our data support the strategy of testing residual specimens for HPV prevalence monitoring in MSM to evaluate the impact of the targeted vaccination programme.
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December 2020

Comprehensive Assessment of the Antigenic Impact of Human Papillomavirus Lineage Variation on Recognition by Neutralizing Monoclonal Antibodies Raised against Lineage A Major Capsid Proteins of Vaccine-Related Genotypes.

J Virol 2020 11 23;94(24). Epub 2020 Nov 23.

Virus Reference Department, Public Health England, London, UK

Human papillomavirus (HPV) is the causative agent of cervical and other epithelial cancers. Naturally occurring variants of HPV have been classified into lineages and sublineages based on their whole-genome sequences, but little is known about the impact of this diversity on the structure and function of viral gene products. The HPV capsid is an icosahedral lattice comprising 72 pentamers of the major capsid protein (L1) and the associated minor capsid protein (L2). We investigated the potential impact of this genome variation on the capsid antigenicity of lineage and sublineage variants of seven vaccine-relevant, oncogenic HPV genotypes by using a large panel of monoclonal antibodies (MAbs) raised against the L1 proteins of lineage A antigens. Each genotype had at least one variant that displayed a ≥4-fold reduced neutralizing antibody sensitivity against at least one MAb, demonstrating that naturally occurring variation can affect one or more functional antigenic determinants on the HPV capsid. For HPV16, HPV18, HPV31, and HPV45, the overall impact was of a low magnitude. For HPV33 (sublineages A2 and A3 and lineages B and C), HPV52 (lineage D), and HPV58 (lineage C), however, variant residues in the indicated lineages and sublineages reduced their sensitivity to neutralization by all MAbs by up to 1,000-fold, suggesting the presence of key antigenic determinants on the surface of these capsids. These determinants were resolved further by site-directed mutagenesis. These data improve our understanding of the impact of naturally occurring variation on the antigenicity of the HPV capsid of vaccine-relevant oncogenic HPV genotypes. Human papillomavirus (HPV) is the causative agent of cervical and some other epithelial cancers. HPV vaccines generate functional (neutralizing) antibodies that target the virus particles (or capsids) of the most common HPV cancer-causing genotypes. Each genotype comprises variant forms that have arisen over millennia and which include changes within the capsid proteins. In this study, we explored the potential for these naturally occurring variant capsids to impact recognition by neutralizing monoclonal antibodies. All genotypes included at least one variant form that exhibited reduced recognition by at least one antibody, with some genotypes affected more than others. These data highlight the impact of naturally occurring variation on the structure of the HPV capsid proteins of vaccine-relevant oncogenic HPV genotypes.
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November 2020

Human papillomavirus (HPV) vaccination and oropharyngeal HPV in ethnically diverse, sexually active adolescents: community-based cross-sectional study.

Sex Transm Infect 2021 Sep 3;97(6):458-460. Epub 2020 Sep 3.

Population Health Research Institute, St George's University of London, London, UK

Objectives: Oropharyngeal squamous cell carcinoma is the most common human papillomavirus (HPV)-associated cancer in the UK, but little is known about the prevalence of oropharyngeal HPV in sexually active teenagers. We investigated reported HPV vaccination coverage (in females) and prevalence of oropharyngeal HPV in sexually active students attending six technical colleges in London, UK.

Methods: In 2017, we obtained mouthwash samples and questionnaires from male and female students taking part in the 'Test n Treat' chlamydia screening trial. Samples were subjected to HPV genotyping.

Results: Of 232 participants approached, 202 (87%) provided a mouthwash sample and questionnaire. Participants' median age was 17 years and 47% were male. Most (73%) were from black and minority ethnic groups, 64% gave a history of oral sex, 52% reported having a new sexual partner in the past 6 months, 33% smoked cigarettes, 5.9% had concurrent genitourinary infection and 1.5% and 5.0% were gay or bisexual. Only 47% (50/107) of females reported being vaccinated against HPV 16/18, of whom 74% had received ≥2 injections. HPV genotyping showed three mouthwash samples (1.5%, 95% CI 0.3% to 4.3%) were positive for possible high-risk human papillomavirus (HR-HPV), one (0.5%, 0.0% to 2.7%) for low-risk HPV 6/11, but none (0.0%, 0.0% to 1.8%) for HR-HPV. Four samples (2.0%, 0.5% to 5.0%) were positive for HPV16 using a HPV16 type-specific quantitative PCR, but these were at a very low copy number and considered essentially negative.

Conclusions: Despite the high prevalence of oral sex and genitourinary chlamydia and low prevalence of HPV vaccination, the prevalence of oropharyngeal HR-HPV in these adolescents was negligible.
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September 2021

Durability of the neutralizing antibody response to vaccine and non-vaccine HPV types 7 years following immunization with either Cervarix® or Gardasil® vaccine.

Vaccine 2019 04 27;37(18):2455-2462. Epub 2019 Mar 27.

Virus Reference Department, Public Health England, London, UK. Electronic address:

Bivalent (Cervarix®) and quadrivalent (Gardasil®) Human Papillomavirus (HPV) vaccines demonstrate remarkable efficacy against the targeted genotypes, HPV16 and HPV18, but also a degree of cross-protection against non-vaccine incorporated genotypes, HPV31 and HPV45. These outcomes seem to be supported by observations that the HPV vaccines induce high titer neutralizing antibodies against vaccine types and lower responses against non-vaccine types. Few data are available on the robustness of the immune response against non-vaccine types. We examined the durability of vaccine and non-vaccine antibody responses in a follow up of a head-to-head study of 12-15 year old girls initially randomized to receive three doses of Cervarix® or Gardasil® vaccine. Neutralizing antibodies against both vaccine and non-vaccine types remained detectable up to 7 years following initial vaccination and a mixed effects model was used to predict the decline in antibody titers over a 15 year period. The decline in vaccine and non-vaccine type neutralizing antibody titers over the study period was estimated to be 30% every 5-7 years, with Cervarix® antibody titers expected to remain 3-4 fold higher than Gardasil® antibody titers over the long term. The antibody decline rates in those with an initial response to non-vaccine types were similar to that of vaccine types and are predicted to remain detectable for many years. Empirical data on the breadth, magnitude, specificity and durability of the immune response elicited by the HPV vaccines contribute to improving the evidence base supporting this important public health intervention. Original trial: NCT00956553.
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April 2019

The Impact of the National HPV Vaccination Program in England Using the Bivalent HPV Vaccine: Surveillance of Type-Specific HPV in Young Females, 2010-2016.

J Infect Dis 2018 08;218(6):911-921

HIV and STI Department, Centre for Infectious Disease Surveillance and Control, London, United Kingdom.

Background: The national human papillomavirus (HPV) immunization program was introduced in England in September 2008 using the bivalent vaccine.

Methods: We collected residual vulva-vaginal swab specimens from 16 to 24-year-old women attending for chlamydia screening between 2010 and 2016 and tested for HPV DNA. We compared changes in type-specific (vaccine and nonvaccine) HPV prevalence over time and association with vaccination coverage. For women with known vaccination status, vaccine effectiveness was estimated.

Results: HPV DNA testing was completed for 15459 specimens. Prevalence of HPV16/18 decreased between 2010/2011 and 2016 from 8.2% to 1.6% in 16-18 year olds and from 14.0% to 1.6% in 19-21 year olds. Declines were also seen for HPV31/33/45 (6.5% to 0.6% for 16-18 year olds and 8.6% to 2.6% for 19-21 year olds). Vaccine effectiveness for HPV16/18 was 82.0% (95% confidence interval [CI], 60.6%-91.8%) and for HPV31/33/45 was 48.7% (95% CI, 20.8%-66.8%). Prevalence of HPV16/18 was compared to findings in 2007-2008 (prevaccination) and to predictions from Public Health England's mathematical model.

Discussion: Eight years after the introduction of a national HPV vaccination program, substantial declines have occurred in HPV16/18 and HPV31/33/45. The prevalence of other high-risk HPV types has not changed.
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August 2018

Human papillomavirus (HPV) in young women in Britain: Population-based evidence of the effectiveness of the bivalent immunisation programme and burden of quadrivalent and 9-valent vaccine types.

Papillomavirus Res 2017 Jun;3:36-41

Research Department of Infection & Population Health, University College London, Mortimer Market Centre, London WC1E 6JB, UK. Electronic address:

Background: In 2008, the UK introduced an HPV immunisation programme in girls. Population-based prevalence estimates of bivalent (HPV-16/18), quadrivalent (HPV-6/11/16/18) and 9-valent (HPV-6/11/16/18/31/33/45/52/58) vaccine types, and comparison over time, are needed to monitor impact, evaluate effectiveness and guide decision-making on vaccination strategies.

Methods: The third National Survey of Sexual Attitudes and Lifestyles (Natsal-3) in 2010-12, tested urine for HPV from 2569 sexually-experienced women aged 16-44. We report type-specific HPV prevalence and compare results with 1798 women in Natsal-2 (1999-2001) using age-adjusted prevalence ratios (APR).

Findings: In Natsal-3, 4.2% of women aged 16-44y were positive for HPV-16/18 and 2.9% for HPV-6/11. In 16-20 year olds, 4.5%, 10.8% and 20.7% had at least one bivalent, quadrivalent or 9-valent vaccine type, respectively. Three-dose vaccine coverage was 52.0% in women aged 18-20y. In this age group, HPV-16/18 prevalence was lower in Natsal-3 than Natsal-2 (5.8% vs 11.2%; APR=0.48[95%CI: 0.24-0.93]), however, prevalences of HPV-6/11, HPV-31/33/45 and HPV-52/58 were unchanged. HPV-16/18 prevalence was also unchanged in women aged 21-44y (APR=0.85[0.61-1.19]).

Interpretation: These probability surveys provide evidence of the impact of the bivalent immunisation programme. Reductions were specific to HPV-16/18 and to the age group eligible for vaccination. However, substantial vaccine-preventable HPV remains.
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June 2017

Continuing reductions in HPV 16/18 in a population with high coverage of bivalent HPV vaccination in England: an ongoing cross-sectional study.

BMJ Open 2016 Feb 11;6(2):e009915. Epub 2016 Feb 11.

HIV & STI Department, Centre for Infectious Disease Surveillance and Control, Public Health England, London, UK.

Objectives: The human papillomavirus (HPV) immunisation programme in England was introduced in 2008. Monitoring changes in type-specific HPV prevalence allows assessment of the population impact of this vaccination programme.

Methods: Residual vulva-vaginal swab specimens were collected from young sexually active women (aged 16-24 years) attending for chlamydia screening across England. Specimens were collected between 2010 and 2013 for type-specific HPV-DNA testing. HPV prevalence was compared to a similar survey conducted in 2008 prior to the introduction of HPV vaccination.

Results: A total of 7321 specimens collected in the postvaccination period, and 2354 specimens from the prevaccination period were included in this analysis. Among the individuals aged 16-18 years, with an estimated vaccination coverage of 67%, the prevalence of HPV16/18 infection decreased from 17.6% in 2008 to 6.1% in the postvaccination period. Within the postvaccination period, there was a trend towards lower HPV16/18 prevalence with higher vaccination coverage and increasing time since vaccine introduction from 8.5% in the period 2-3 years postvaccination to 4.0% in the period 4-5 years postvaccination. The prevalence of HPV31 reduced from 3.7% in the prevaccination period to 0.9% after vaccine introduction, although this no longer reached statistical significance after additional consideration of the uncertainty due to the assay change. Smaller reductions were seen in the individuals aged 19-21 years with lower estimated vaccination coverage, but there was no evidence of a reduction in the older unvaccinated women. Some overall increase in non-vaccine types was seen in the youngest age groups (ORs (95% CI); 1.3 (1.0 to 1.7) and 1.5 (1.1 to 2.0) for individuals aged 16-18 and 19-21 years, respectively, when adjusted for known population changes and the change in assay) although this should be interpreted with caution given the potential unmasking effect.

Conclusions: These data demonstrate a reduction in the HPV vaccine types in the age group with the highest HPV vaccination coverage.
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February 2016

Male Circumcision and STI Acquisition in Britain: Evidence from a National Probability Sample Survey.

PLoS One 2015 17;10(6):e0130396. Epub 2015 Jun 17.

Research Department of Infection and Population Health, University College London, London, United Kingdom.

Background: It is well-established that male circumcision reduces acquisition of HIV, herpes simplex virus 2, chancroid, and syphilis. However, the effect on the acquisition of non-ulcerative sexually transmitted infections (STIs) remains unclear. We examined the relationship between circumcision and biological measures of three STIs: human papillomavirus (HPV), Chlamydia trachomatis and Mycoplasma genitalium.

Methods: A probability sample survey of 15,162 men and women aged 16-74 years (including 4,060 men aged 16-44 years) was carried out in Britain between 2010 and 2012. Participants completed a computer-assisted personal interview, including a computer-assisted self-interview, which asked about experience of STI diagnoses, and circumcision. Additionally, 1,850 urine samples from sexually-experienced men aged 16-44 years were collected and tested for STIs. Multivariable logistic regression was used to calculate adjusted odds ratios (AOR) to quantify associations between circumcision and i) self-reporting any STI diagnosis and ii) presence of STIs in urine, in men aged 16-44 years, adjusting for key socio-demographic and sexual behavioural factors.

Results: The prevalence of circumcision in sexually-experienced men aged 16-44 years was 17.4% (95%CI 16.0-19.0). There was no association between circumcision and reporting any previous STI diagnoses, and specifically previous chlamydia or genital warts. However, circumcised men were less likely to have any HPV type (AOR 0.26, 95% confidence interval (CI) 0.13-0.50) including high-risk HPV types (HPV-16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59 and/or 68) (AOR 0.14, 95% CI 0.05-0.40) detected in urine.

Conclusions: Circumcised men had reduced odds of HPV detection in urine. These findings have implications for improving the precision of models of STI transmission in populations with different circumcision prevalence and in designing interventions to reduce STI acquisition.
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May 2016

Oral human papillomavirus (HPV) infection in men who have sex with men: prevalence and lack of anogenital concordance.

Sex Transm Infect 2015 Jun 17;91(4):284-6. Epub 2015 Apr 17.

Research Department of Infection and Population Health, University College London, London, UK.

Objectives: To estimate the prevalence of oral detectable human papillomavirus (HPV) DNA in HIV-negative men who have sex with men (MSM) attending a sexual health clinic in London and concordance with anogenital HPV infection. Such data are important to improve our understanding of the epidemiology of oral HPV and the potential use of vaccines to prevent oropharyngeal cancers.

Methods: Paired oral rinse samples and anogenital samples were available from 151 HIV-negative MSM within a larger cross-sectional survey. All samples were tested in parallel for 21 types of HPV DNA using an in-house assay.

Results: The median age of participants was 30 (IQR 25-35). The prevalence of any oral HPV and of high-risk HPV (HR-HPV) was 13.7% (n=21; 95% CI 8.7 to 20.2) and 5.9% (n=9; 95% CI 2.7 to 10.9) compared with 64.9% (n=98; 95% CI 56.7 to 72.5) and 34.4% (n=52; 95% CI 26.9 to 42.6) in any anogenital sample, respectively. The prevalence of types prevented by the bivalent (HPV16/18), quadrivalent (HPV6/11/16/18) and nonavalent (HPV6/11/16/18/31/33/45/52/58) vaccines was 1.3% (95% CI 0.2 to 4.7), 2.6% (95% CI 0.7 to 6.6) and 4.6% (95% CI 1.9 to 9.3), respectively. There was no concordance between HPV genotypes detected in oral and anogenital sites.

Conclusions: HR-HPV DNA, including HPV 16/18, was detected in oral specimens from HIV-negative MSM attending sexual health clinics, suggesting a potential role for vaccination, but is far less common than anogenital infection. How this relates to the risk and natural history of HPV-related head and neck cancers warrants further study. Lack of concordance with anogenital infection also suggests that oral HPV infection should be considered separately when estimating potential vaccine impact.
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June 2015

High-Risk Human Papillomavirus (HPV) Infection and Cervical Cancer Prevention in Britain: Evidence of Differential Uptake of Interventions from a Probability Survey.

Cancer Epidemiol Biomarkers Prev 2015 May 3;24(5):842-53. Epub 2015 Mar 3.

Research Department of Infection and Population Health, University College London, London, United Kingdom.

Background: The third British National Survey of Sexual Attitudes and Lifestyles (Natsal-3) provides an opportunity to explore high-risk human papillomavirus (HR-HPV) and uptake of cervical screening and HPV vaccination in the general population.

Methods: Natsal-3, a probability sample survey of men and women ages 16 to 74, resident in Britain, interviewed 8,869 women in 2010 to 2012. We explored risk factors for HR-HPV (in urine from 2,569 sexually experienced women ages 16 to 44), nonattendance for cervical screening in the past 5 years, and noncompletion of HPV catch-up vaccination.

Results: HR-HPV was associated with increasing numbers of lifetime partners, younger age, increasing area-level deprivation, and smoking. Screening nonattendance was associated with younger and older age, increasing area-level deprivation (age-adjusted OR 1.91, 95% confidence interval, 1.48-2.47 for living in most vs. least deprived two quintiles), Asian/Asian British ethnicity (1.96, 1.32-2.90), smoking (1.97, 1.57-2.47), and reporting no partner in the past 5 years (2.45, 1.67-3.61 vs. 1 partner) but not with HR-HPV (1.35, 0.79-2.31). Lower uptake of HPV catch-up vaccination was associated with increasing area-level deprivation, non-white ethnicity, smoking, and increasing lifetime partners.

Conclusions: Socioeconomic markers and smoking were associated with HR-HPV positivity, nonattendance for cervical screening, and noncompletion of catch-up HPV vaccination.

Impact: The cervical screening program needs to engage those missing HPV catch-up vaccination to avoid a potential widening of cervical cancer disparities in these cohorts. As some screening nonattenders are at low risk for HR-HPV, tailored approaches may be appropriate to increase screening among higher-risk women.
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May 2015