A survey-based assessment of rates and covariates of mpox diagnosis and vaccination provides evidence to refine eligibility criteria for mpox vaccination among gay, bisexual and other men who have sex with men in the Netherlands.

Background: The 2022 multicountry mpox outbreaks predominantly affected gay, bisexual and other men who have sex with men (GBMSM) in non-endemic countries, including in the Netherlands. We conducted a survey-based assessment of the alignment between the risk factors associated with mpox diagnosis among GBMSM in the Netherlands and the eligibility criteria used in 2022 for vaccinating this group, with the aim to refine these criteria. Methods: An online self-report survey was conducted among adult GBMSM in the Netherlands between 29 July and 30 August 2022, corresponding to the first month of the Dutch mpox vaccination campaign. GBMSM were recruited via advertisements on social media and gay dating apps. Participants reported on their sexual behaviour, mpox diagnosis, and/or (initial) mpox vaccination since the start of the outbreak. Covariables of mpox diagnosis and vaccination were assessed using logistic regression analyses. Results: Of the 2,460 participants, 73 (3.0%, 95% CI 2.3-3.6%) were diagnosed with mpox and 485 (19.7%, 95% CI 18.1-21.3%) had received (initial) mpox vaccination. Using sample weighting, we estimated that, of the GBMSM population aged 18-80 years in the Netherlands, 1.1% (95% CI 0.7-1.6%) had been diagnosed with mpox and 7.8% (95% CI 6.8-8.9%) had received (initial) vaccination. HIV-PrEP use, living with HIV, reporting ≥20 sex partners in the past 12 months, and sex in sex venues/parties in the past 2 months were independent risk factors for mpox diagnosis. Except for sex in sex venues/parties, these variables were also independently associated with mpox vaccination. Conclusion: This study provides novel evidence regarding the degree to which the 2022 eligibility criteria for mpox vaccination align with the risk factors for mpox among GBMSM in the Netherlands. The findings contribute to a refinement of the eligibility criteria for mpox vaccination, to which sex in sex venues/parties should be added.

The fading of the mpox outbreak among men who have sex with men: a mathematical modelling study.

BACKGROUND: In the Netherlands, the number of mpox cases started declining before mpox vaccination was initiated. Most cases were men who have sex with men (MSM). We investigated whether the decline in mpox could be attributed to infection-induced immunity or behavioural adaptations. METHODS: We developed a transmission model and accounted for possible behavioural adaptations: less casual partners and shorter time until MSM with mpox refrain from sexual contacts. RESULTS: Without behavioural adaptations, the peak in modelled cases matched observations, but the decline was less steep than observed. With behavioural adaptations in the model, we found a decline of 16-18% in numbers of casual partners in June and 13-22% in July 2022. Model results showed a halving of the time before refraining from sex. When mpox vaccination started, 57% of MSM with very high sexual activity in the model had been infected. Model scenarios revealed that the outbreak could have waned by November 2022 even without vaccination. CONCLUSIONS: The limited duration of the mpox outbreak in the Netherlands can be ascribed primarily to infection-induced immunity among MSM with high sexual activity levels. The decline was accelerated by behavioural adaptations. Immunity among those most sexually active is essential to impede mpox resurgence.

Eligibility criteria vs. need for pre-exposure prophylaxis: a reappraisal among men who have sex with men in Amsterdam, the Netherlands.

To reappraise pre-exposure prophylaxis (PrEP) eligibility criteria towards the men who have sex with men (MSM) with highest HIV-risk, we assessed PrEP need (i.e. HIV-risk) using Amsterdam Cohort Studies data from 2011-2017 for all non-PrEP using MSM. Outcomes were incident HIV-infection and newly-diagnosed anal STI. Determinants were current PrEP eligibility criteria (anal STI and condomless sex (CAS)) and additional determinants (age, education, group sex, alcohol use during sex and chemsex). We used targeted maximum likelihood estimation (TMLE) to estimate the relative risk (RR) and 95% confidence intervals (CI) of determinants on outcomes, and calculated population attributable fractions (PAFs) with 95% CI using RRs from TMLE. Among 810 included MSM, 22 HIV-infections and 436 anal STIs (n = 229) were diagnosed during follow-up. Chemsex (RR = 5.8 (95% CI 2.0-17.0); PAF = 55.3% (95% CI 43.3-83.4)), CAS with a casual partner (RR = 3.3 (95% CI 1.3-8.7); PAF = 38.0% (95% CI 18.3-93.6)) and anal STI (RR = 5.3 (95% CI 1.7-16.7); PAF = 22.0 (95% CI -16.8 to 100.0)) were significantly (P < 0.05) associated with and had highest attributable risk fractions for HIV. Chemsex (RR = 2.0 (95% CI 1.6-2.4); PAF = 19.5 (95% CI 10.6-30.6)) and CAS with a casual partner (RR = 2.5 (95% CI 2.0-3.0); PAF = 28.0 (95% CI 21.0-36.4)) were also significantly associated with anal STI, as was younger age (16-34/≥35; RR = 1.7 (95% CI 1.4-2.1); PAF = 15.5 (95% CI 6.4-27.6)) and group sex (RR = 1.3 (95% CI 1.1-1.6); PAF = 9.0 (95% CI -2.3 to 23.7)). Chemsex should be an additional PrEP eligibility criterion.

The impact of the COVID-19 pandemic on hepatitis B virus vaccination and transmission among men who have sex with men: A mathematical modelling study.

BACKGROUND: During the COVID-19 pandemic, the number of hepatitis B virus (HBV) vaccinations among men who have sex with men (MSM) has been considerably lower than before the pandemic. Moreover, less frequent HBV testing and a reduction in numbers of sex partners have been reported. We assessed the impact of these COVID-19-related changes on HBV transmission among MSM in the Netherlands. METHODS: We estimated the changes in sexual activity, HBV testing, and HBV vaccination among MSM during the pandemic from Dutch data. We used a deterministic compartmental model and investigated scenarios with small or large declines in sexual activity, testing, and vaccination for the current phase of the pandemic (without available data). We examined the increase in HBV vaccinations needed to prevent further increase in HBV incidence. RESULTS: With a decrease in numbers of sex partners of 15-25% during the first lockdown and 5% during the second lockdown, we found a decline of 6.6% in HBV incidence in 2020, despite a >70% reduction in HBV testing and vaccination during the first lockdown. With numbers of sex partners rebounding close to pre-pandemic level in 2021, and a reduction of 15% in testing and 30% in vaccination in 2021, we found an increase of 1.4% in incidence in 2021 and 3.1% in 2026. With these changes, an increase of ≥60% in HBV vaccinations in 2022 would be needed to bring the HBV incidence in 2023 back to the level that it would have had if the COVID-19-related changes had not occurred. CONCLUSIONS: Despite reductions in sexual activity during the COVID-19 pandemic, the decrease in HBV vaccinations may result in a small increase in HBV incidence after 2021, which may persist for years. It is important to restore the vaccination level and limit further increase in HBV transmission among MSM.

Estimated incubation period for monkeypox cases confirmed in the Netherlands, May 2022.

In May 2022, monkeypox outbreaks have been reported in countries not endemic for monkeypox. We estimated the monkeypox incubation period, using reported exposure and symptom-onset times for 18 cases detected and confirmed in the Netherlands up to 31 May 2022. Mean incubation period was 9.0 [corrected] days (5th-95th percentiles: 4.2-17.3), underpinning the current recommendation to monitor or isolate/quarantine case contacts for 21 days. However, as the incubation period may differ between different transmission routes, further epidemiological investigations are needed.

How the Disruption in Sexually Transmitted Infection Care Due to the COVID-19 Pandemic Could Lead to Increased Sexually Transmitted Infection Transmission Among Men Who Have Sex With Men in The Netherlands: A Mathematical Modeling Study.

BACKGROUND: During the COVID-19 pandemic, the disruption in care for sexually transmitted infections (STIs) and the social distancing measures have led to reductions in STI testing and sexual behavior. We assessed the impact of these COVID-19-related changes on transmission of Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) among men who have sex with men (MSM) in The Netherlands. METHODS: We developed a mathematical model for CT and NG transmission among MSM, accounting for COVID-19-related changes in sexual behavior and testing in 2020 to 2021. Changes in 2020 were estimated from data from the Dutch COVID-19, Sex, and Intimacy Survey among MSM and the National Database of STI Clinics. Because of the lack of data for 2021, we examined several scenarios covering a range of changes. RESULTS: A reduction of 10% and 40% in STI testing of symptomatic and asymptomatic, respectively, individuals with a 10% to 20% reduction in numbers of casual partners (according to partner status and activity level) during the second lockdown, resulted in a 2.4% increase in CT prevalence, but a 2.8% decline in NG prevalence in 2021. A 5% and 30% reduction in STI testing of symptomatic and asymptomatic, respectively, individuals with the same reduction in casual partners resulted in a 0.6% increase in CT prevalence and a 4.9% decrease in NG prevalence in 2021. CONCLUSIONS: The disruption in STI care due to COVID-19 might have resulted in a small increase in CT prevalence, but a decrease in NG prevalence. Scaling up STI care is imperative to prevent increases in STI transmission.

Offering a choice of daily and event-driven preexposure prophylaxis for men who have sex with men in the Netherlands: a cost-effectiveness analysis.

OBJECTIVES: To assess the cost-effectiveness of a preexposure prophylaxis (PrEP) programme offering a choice of daily and event-driven PrEP for men who have sex with men (MSM) in the Netherlands. METHODS: We used an agent-based transmission model and an economic model to simulate a programme offering only daily PrEP and a programme offering daily and event-driven PrEP. Use of PrEP medication and preference for daily versus event-driven PrEP were estimated from the Amsterdam PrEP Demonstration Project (AMPrEP). We calculated costs, quality-adjusted life-years (QALY), and incremental cost-effectiveness ratios (ICER), over 2018-2027. An ICER less than €20 000 per QALY gained was considered cost-effective. RESULTS: Using AMPrEP data, we estimated that 27% of PrEP users chose event-driven PrEP with a median of 12 pills per month; daily PrEP users used a median of 30 pills per month. With PrEP, 3740 HIV infections were averted and 1482 QALYs were gained over 2018-2027, compared to the scenario without PrEP. The probability of the PrEP programme being cost-effective (compared to not having a PrEP programme) increased from 91% with daily PrEP to 94% with a choice of daily and event-driven PrEP. The probability of being cost-saving increased from 42% with only daily PrEP to 48% with choice of daily and event-driven PrEP. CONCLUSIONS: A daily PrEP programme for MSM would be cost-effective. Providing a choice of daily and event-driven PrEP can result in savings and is more likely to be cost-effective and cost-saving, compared to a programme offering only daily PrEP.

Ending risk-group HBV vaccination for MSM after the introduction of universal infant HBV vaccination: A mathematical modelling study.

BACKGROUND: Risk-group HBV vaccination for men who have sex with men (MSM) was introduced in the Netherlands in 2002, followed by universal infant vaccination in 2011, that will enable termination of risk-group vaccination over time. The introduction of pre-exposure prophylaxis (PrEP) for HIV prevention might result in increased HBV testing and vaccination against HBV. The aim of this study was to investigate the impact of the transition from risk-group to universal HBV vaccination, accounting for improvements in HBV testing and treatment, as well as the introduction of PrEP. METHODS: We developed a mathematical model for HBV transmission among MSM. Universal vaccination was modelled by assigning some MSM (5-15% in 2028 increasing to 80-90% in 2033 and thereafter) to be vaccinated when they become sexually active. We investigated different scenarios assuming 0.5% extra vaccination rate and 0.5% extra testing rate due to PrEP consultations; and 5% of HIV-negative MSM on PrEP, that will reduce the probability of HBV acquisition by 88%. RESULTS: Universal vaccination resulted in a reduction of 24% (interquartile range; 22-25%) of the total number of HBV infections among MSM estimated to occur from 2020 to 2070. With universal vaccination, terminating risk-group vaccination in 2030 or 2040 resulted in 30% or 10% more HBV infections over 2020-2070, respectively, compared to continuation of risk-group vaccination until 2070. With PrEP and continued risk-group vaccination, the total number of HBV infections over 2020-2070 was reduced by 13%. CONCLUSIONS: Universal HBV vaccination can lead to a major reduction in HBV incidence among MSM in the future. The reduction becomes smaller when ending risk-group HBV vaccination, but larger by PrEP use for HIV prevention. Efforts to keep high levels of HBV vaccination, testing, and treatment have to be continued in the coming decades in order to eliminate HBV as a health threat for MSM.

Preexposure prophylaxis for men who have sex with men in the Netherlands: impact on HIV and Neisseria gonorrhoeae transmission and cost-effectiveness.

OBJECTIVES: To assess the impact of a preexposure prophylaxis (PrEP) programme for high-risk men who have sex with men (MSM), which includes gonorrhoea testing and treatment, on the transmission of HIV and Neisseria among MSM in the Netherlands and the cost-effectiveness of such programme with and without risk compensation (in the form of reduced condom use). METHODS: We developed a stochastic agent-based transmission model of HIV and gonorrhoea. We simulated a capped (max 2.5% of MSM) and uncapped (5.5% of MSM in 2018 declining to 3% in 2027) daily PrEP programme for high-risk MSM, with 3-monthly HIV and gonorrhoea testing, with and without risk compensation. Epidemiological outcomes were calculated from the transmission model and used in an economic model to calculate costs, quality-adjusted life-years (QALY), and incremental cost-effectiveness ratios (ICER), over 2018-2027, taking a healthcare payer perspective. RESULTS: Without risk compensation, PrEP can lead to a reduction of 61 or 49% in the total number of new HIV infections in 2018-2027, if the programme is uncapped or capped to 2.5% of MSM, respectively. With risk compensation, this reduction can be 63 or 46% in the uncapped and capped programmes, respectively. In all scenarios, gonorrhoea prevalence decreased after introducing PrEP. Without risk compensation, 92% of simulations were cost-effective (of which 52% cost-saving). With risk compensation, 73% of simulations were cost-effective (of which 23% was cost-saving). CONCLUSION: A nationwide PrEP programme for high-risk MSM can result in substantial reductions in HIV and gonorrhoea transmission and be cost-effective, even with risk compensation.

Impact of frequent testing on the transmission of HIV and N. gonorrhoeae among men who have sex with men: a mathematical modelling study.

OBJECTIVES: To investigate the impact and efficiency of combined testing for HIV and other STIs on HIV and STI transmission among men who have sex with men (MSM) and to assess what subgroups of MSM should be targeted for frequent testing. METHODS: We developed an agent-based transmission model that simulates infection with HIV or Neisseria gonorrhoeae (NG) among MSM. We examined scenarios with increased percentages of MSM getting tested six monthly, among all MSM or only specific subgroups of MSM (defined according to recent gonorrhoea, number of partners and engagement in condomless anal intercourse (CAI)) and scenarios with reduced intervals between HIV/STI tests. RESULTS: The most efficient strategies were those with increased percentage of MSM getting tested every 6 months among MSM with a recent gonorrhoea diagnosis; or among MSM who had CAI and ≥10 partners; or MSM who had ≥10 partners. Over 10 years, these strategies resulted in 387-718 averted HIV infections and required 29-164 additional HIV tests per averted HIV infection or one to seven additional gonorrhoea tests per averted NG infection. The most effective strategy in reducing HIV transmission was the one where the intervals between tests were reduced by half, followed by the strategy with increased percentage of MSM getting tested every 6 months among all MSM. Over 10 years, these strategies resulted in 1362 and 1319 averted HIV infections, but required 663 and 584 additional HIV tests per averted HIV infection, respectively. CONCLUSIONS: Targeting MSM with recent gonorrhoea diagnosis or MSM with many partners is efficient in terms of HIV/STI tests needed to prevent new HIV or NG infections. Major reductions in HIV incidence can be achieved with consistent HIV/STI testing every 6 months among larger groups, including low-risk MSM. To impede HIV transmission, frequent testing should be combined with other prevention measures.

Cost-effectiveness of increased HIV testing among MSM in The Netherlands.

OBJECTIVES: To assess the cost-effectiveness of increased consistent HIV testing among MSM in the Netherlands. METHODS: Among MSM testing at sexually transmitted infection clinics in the Netherlands in 2014-2015, approximately 20% tested consistently every 6 months. We examined four scenarios with increased percentage of MSM testing every 6 months: a small and a moderate increase among all MSM; a small and a moderate increase only among MSM with at least 10 partners in the preceding 6 months. We used an agent-based model to calculate numbers of HIV infections and AIDS cases prevented with increased HIV testing. These numbers were used in an economic model to calculate costs, quality-adjusted life-years (QALYs), and incremental cost-effectiveness ratios (ICERs) due to increased testing, over 2018-2027, taking a healthcare payer perspective. RESULTS: A small increase in the percentage testing every 6 months among all MSM resulted in 490 averted HIV infections and an average ICER of &OV0556;27 900/QALY gained. A moderate increase among all MSM, resulted in 1380 averted HIV infections and an average ICER of &OV0556;36 700/QALY gained. Both were not cost-effective, with a &OV0556;20 000 willingness-to-pay threshold. Increasing the percentage testing every 6 months only among MSM with at least 10 partners in the preceding 6 months resulted in less averted HIV infections than increased testing among all MSM, but was on average cost-saving. CONCLUSION: Increased HIV testing can prevent considerable numbers of new HIV infections among MSM, but may be cost-effective only if targeted at high-risk individuals, such as those with many partners.

Potential effectiveness of prophylactic HPV immunization for men who have sex with men in the Netherlands: A multi-model approach.

BACKGROUND: Men who have sex with men (MSM) are at high risk for anal cancer, primarily related to human papillomavirus genotype 16 (HPV16) infections. At 8.5 per 100,000 per year, the incidence rate of anal cancer among MSM is similar to that of cervical cancer among adult women in the Netherlands. However, MSM are not included in most HPV vaccination programs. We explored the potential effectiveness of prophylactic immunization in reducing anogenital HPV16 transmission among MSM in the Netherlands. METHODS AND FINDINGS: We developed a range of mathematical models for penile-anal HPV16 transmission, varying in sexual contact structure and natural history of infection, to provide robust and plausible predictions about the effectiveness of targeted vaccination. Models were informed by an observational cohort study among MSM in Amsterdam, 2010-2013. Parameters on sexual behavior and HPV16 infections were obtained by fitting the models to data from 461 HIV-negative study participants, considered representative of the local MSM population. We assumed 85% efficacy of vaccination against future HPV16 infections as reported for HIV-negative MSM, and age-specific uptake rates similar to those for hepatitis B vaccination among MSM in the Netherlands. Targeted vaccination was contrasted with vaccination of 12-year-old boys at 40% uptake in base-case scenarios, and we also considered the effectiveness of a combined strategy. Offering vaccine to MSM without age restrictions resulted in a model-averaged 27.3% reduction (90% prediction interval [PI] 11.9%-37.5%) in prevalence of anal HPV16 infections, assuming similar uptake among MSM as achieved for hepatitis B vaccination. The predicted reduction improved to 46.1% (90% PI 21.8%-62.4%) if uptake rates among MSM were doubled. The reductions in HPV16 infection prevalence were mostly achieved within 30 years of a targeted immunization campaign, during which they exceeded those induced by vaccinating 40% of preadolescent boys, if started simultaneously. The reduction in anal HPV16 prevalence amounted to 74.8% (90% PI 59.8%-93.0%) under a combined vaccination strategy. HPV16 prevalence reductions mostly exceeded vaccine coverage projections among MSM, illustrating the efficiency of prophylactic immunization even when the HPV vaccine is given after sexual debut. Mode of protection was identified as the key limitation to potential effectiveness of targeted vaccination, as the projected reductions were strongly reduced if we assumed no protection against future infections in recipients with prevalent infection or infection-derived immunity at the time of immunization. Unverified limitations of our study include the sparsity of data to inform the models, the omission of oral sex in transmission to the penile or anal site, and the restriction that our modeling results apply primarily to HIV-negative MSM. CONCLUSIONS: Our findings suggest that targeted vaccination may generate considerable reductions in anogenital HPV16 infections among MSM, and has the potential to accelerate anal cancer prevention, especially when combined with sex-neutral vaccination in preadolescence.

Microscopic examination of Gram-stained smears for anogenital gonorrhoea in men who have sex with men is cost-effective: evidence from a modelling study.

OBJECTIVE: To assess the cost-effectiveness of three testing strategies with or without light microscopic Gram-stained smear (GSS) evaluation for the detection of anogenital gonorrhoea among men who have sex with men (MSM) at the Amsterdam STI clinic using a healthcare payer perspective. METHODS: Three testing strategies for MSM were compared: (1) GSS in symptomatic MSM only (currently practised strategy), (2) no GSS and (3) GSS in symptomatic and asymptomatic MSM. The three testing protocols include testing with nucleic acid amplification test to verify the GSS results in (1) and (3), or as the only test in (2). A transmission model was employed to calculate the influence of the testing strategies on the prevalence of anogenital gonorrhoea over 10 years. An economic model combined cost data on medical consultations, tests and treatment and utility data to estimate the number of epididymitis cases and quality-adjusted life years (QALY) associated with gonorrhoea. Incremental cost-effectiveness ratios (ICERs) for the testing scenarios were estimated. Uncertainty and sensitivity analyses were performed. RESULTS: No GSS testing compared with GSS in symptomatic MSM only (current strategy) resulted in nine extra epididymitis cases (95% uncertainty interval (UI): 2-22), 72 QALYs lost (95% UI: 59-187) and €7300 additional costs (95% UI: -€185 000 (i.e.cost-saving) to €407 000) over 10 years. GSS testing in both symptomatic and asymptomatic MSM compared with GSS in symptomatic MSM only resulted in one prevented epididymitis case (95% UI: 0-2), 1.1 QALY gained (95% UI: 0.1-3.3), €148 000 additional costs (95% UI: €86 000 to-€217 000) and an ICER of €177 000 (95% UI: €67 000-to €705 000) per QALY gained over 10 years. The results were robust in sensitivity analyses. CONCLUSIONS: GSS for symptomatic MSM only is cost-effective compared with no GSS for MSM and with GSS for both symptomatic and asymptomatic MSM.

Impact of point-of-care management on the transmission of anogenital gonococcal infections among men who have sex with men in Amsterdam: a mathematical modelling and cost-effectiveness study.

OBJECTIVE: Point-of-care (POC) management may avert ongoing transmissions occurring between testing and treatment or due to loss to follow-up. We modelled the impact of POC management of anogenital gonorrhoea (with light microscopic evaluation of Gram stained smears) among men who have sex with men (MSM) on gonorrhoea prevalence and testing and treatment costs. METHODS: Data concerning costs and sexual behaviour were collected from the STI clinic of Amsterdam. With a deterministic model for gonorrhoea transmission, we calculated the prevalence of gonorrhoea in MSM in Amsterdam and the numbers of consultations at our clinic over 5 years, in three testing scenarios: POC for symptomatic MSM only (currently routine), POC for all MSM and no POC for MSM. RESULTS: Among MSM, 34.7% (109/314) had sexual contacts in the period between testing and treatment, of whom 22.9% (25/109) had unprotected anal intercourse. Expanding POC testing from symptomatic MSM to all MSM could result in an 11% decrease (IQR, 8%-15%) in gonorrhoea prevalence after 5 years and a cost increase of 8.6% (€2.40) per consultation and €86 118 overall (+8.3%). Switching from POC testing of symptomatic MSM to no POC testing could save €1.83 per consultation (6.5%) and €54 044 (-5.2%) after 5 years with a 60% (IQR, 26%-127%) gonorrhoea prevalence increase. Overtreatment was 2.1% (30/1411) with POC for symptomatic MSM only and 4.1% (68/1675) with POC for all MSM. CONCLUSIONS: In the Amsterdam setting, possible abandonment of POC testing of symptomatic MSM because of budget cuts could result in a considerable increase in gonorrhoea prevalence against a reduction in costs per consultation. Expanding POC testing to all MSM could result in a modest reduction in prevalence and a cost increase. While the costs and outcomes depend on specific local characteristics, the developed framework of this study is useful to evaluate POC management in other settings.

Cost-Effectiveness of Dual Antimicrobial Therapy for Gonococcal Infections Among Men Who Have Sex With Men in the Netherlands.

BACKGROUND: In response to the rising threat of resistance to first-line antibiotics for gonorrhea, international guidelines recommend dual antimicrobial therapy. However, some countries continue to recommend monotherapy. We assess the cost-effectiveness of dual therapy with ceftriaxone and azithromycin compared with monotherapy with ceftriaxone, for control of gonorrhea among men who have sex with men in the Netherlands. METHODS: We developed a transmission model and calculated the numbers of new gonorrhea infections, consultations at health care specialists, tests, and antibiotic doses. With these numbers, we calculated costs and quality-adjusted life-years (QALY) with each treatment; and the incremental cost-effectiveness ratio (ICER) of dual therapy compared to monotherapy. The impact of gonorrhea on human immunodeficiency virus transmission was not included in the model. RESULTS: In the absence of initial resistance, dual therapy can delay the spread of ceftriaxone resistance by at least 15 years, compared to monotherapy. In the beginning, when there is no resistance, dual therapy results in high additional costs, without any QALY gains. When resistance spreads over time, the additional costs of dual therapy decline, the gained QALYs increase, the ICER drops off and, after 50 years, falls below &OV0556;20,000 per QALY gained. If azithromycin resistance is initially prevalent, resistance to the first-line treatment rises almost equally fast with both treatment strategies and the ICER remains extremely high. CONCLUSIONS: Compared with ceftriaxone monotherapy, dual therapy with ceftriaxone and azithromycin can considerably delay the spread of ceftriaxone resistance, but may only be cost-effective in the long run and in the absence of initial resistance.

Does online dating lead to higher sexual risk behaviour? A cross-sectional study among MSM in Amsterdam, the Netherlands.

BACKGROUND: Men having sex with men (MSM) frequently use the Internet to find sex partners. We examined the association between unprotected anal intercourse (UAI) with partners dated online and with partners dated offline (met elsewhere), and examined whether differences can be explained by self-perceived HIV status of the index and knowledge of partnership characteristics. METHODS: MSM were recruited at the Sexually Transmitted Infections Clinic in Amsterdam, in 2008-2009. Participants completed a questionnaire concerning sexual behaviour. Only men reporting both online and offline casual sex partners were included. We assessed the association between online/offline partner dating and UAI, using random-effects logistic regression analysis. RESULTS: Five hundred seventy-seven men (351 HIV-negative, 153 HIV-positive, and 73 HIV-unaware) reported UAI in 26 % of 878 online, and 23 % of 903 offline casual partnerships. The crude OR of online dating for UAI was 1.36 (95 % CI 1.03-1.81). HIV-positive men were more likely to report UAI than HIV-negative men (49 % vs. 28 % of partnerships). Adjusted for demographic characteristics, online dating had no significant effect on UAI among HIV-negative and HIV status-unaware men, but HIV-positive men were more likely to have UAI with online partners (aOR = 1.65 [95 % CI 1.05-2.57]). After correction for partner and partnership characteristics the effect of online/offline dating on UAI among HIV-positive MSM was reduced and no longer significant. CONCLUSIONS: Online dating was not significantly associated with UAI among HIV-negative MSM. HIV-positive MSM were more likely to practise UAI with partners dated online; however, after correction for partner and partnership characteristics, online partnership acquisition was not associated with a significantly increased risk of UAI.

Changing Patterns of Undiagnosed HIV Infection in the Netherlands: Who Benefits Most from Intensified HIV Test and Treat Policies?

OBJECTIVES: To estimate HIV prevalence, the number of people living with HIV/AIDS (PLWHA) and the undiagnosed proportion in the Netherlands for 2012, and to compare these with published 2007 estimates. DESIGN: Synthesis of all available data sources. METHODS: Multi-Parameter Evidence Synthesis (MPES) was used to obtain estimates in mutually exclusive key populations at higher risk in three geographical regions (Amsterdam, Rotterdam, rest of the Netherlands). Data sources included HIV prevalence surveys, diagnoses at STI clinics, and registered cases in HIV care. Group specific estimates were reported as Bayesian posterior medians and 95% credible intervals (CrI). RESULTS: The 2012 model estimated 24,350 PLWHA (95% CrI 20,420-31,280) aged 15-70 years; 2,906 (+14%) more than in 2007. The estimated population HIV prevalence was 0.20% (95% CrI 0.17-0.26%). The overall proportion of undiagnosed HIV was lower in 2012 (34%, 95% CrI 22-49%) compared to 2007 (40%, 95% CrI 25-55%). After MSM, migrants from sub-Saharan Africa and the Caribbean formed the largest groups of PLWHA, but proportions of undiagnosed HIV remained high in these groups, 48% and 44% respectively. Amsterdam had lowest proportions undiagnosed for most key populations at higher risk, including MSM and migrants. CONCLUSIONS: In 2012, the number of PLWHA was higher compared to 2007, while the proportion of undiagnosed HIV was lower, especially among MSM. Higher HIV testing rates, earlier treatment, and an improved life expectancy may explain these differences. HIV interventions need to be expanded in all key populations at higher risk, with special focus on migrants and key populationsliving outside of Amsterdam.

HPV seroconversion following anal and penile HPV infection in HIV-negative and HIV-infected MSM.

BACKGROUND: We assessed human papillomavirus (HPV) seroconversion following anal and penile HPV infection in HIV-negative and HIV-infected men who have sex with men (MSM). METHODS: MSM aged ≥18 years were recruited in Amsterdam, the Netherlands (2010-2011), and followed up semiannually. Antibodies against 7 high-risk HPV types in baseline and 12-month serum samples were tested using a multiplex immunoassay. Baseline, 6-, and 12-month anal and penile samples were tested for HPV DNA using the SPF10-PCR DEIA/LiPA25 system. Statistical analyses were performed using logistic regression with generalized estimating equations. RESULTS: Of 644 MSM included in the analysis, 245 (38%) were HIV-infected. Median age was 38 years for HIV-negative and 47 years for HIV-infected MSM (P < 0.001). Seroconversion against ≥1 of the 7 HPV types was observed in 74 of 396 (19%) HIV-negative and 52 of 223 (23%) HIV-infected MSM at risk (P = 0.2). Incident [adjusted OR (aOR) 2.0; 95% confidence interval (CI), 1.1-3.4] and persistent (aOR 3.7; 95% CI, 1.5-9.5) anal HPV infections were independently associated with type-specific seroconversion in HIV-negative MSM. In HIV-infected MSM, there was a nonsignificant positive association between penile HPV infection at any time point and seroconversion (aOR 1.7; 95% CI, 0.9-3.2). CONCLUSIONS: Incident or persistent anal HPV infection was an independent determinant of seroconversion in HIV-negative MSM. IMPACT: Our data support that seroresponse may vary per anatomic site and that persistent HPV infections are more likely to elicit a detectable humoral immune response.

Perceived HIV status is a key determinant of unprotected anal intercourse within partnerships of men who have sex with men in Amsterdam.

The practice of unprotected anal intercourse (UAI) involves at least two partners. We examined the associations between insertive or receptive UAI and perceived HIV seroconcordance and partnership type in self-perceived HIV-negative and self-perceived HIV-positive men who have sex with men (MSM). MSM (age ≥ 18 years) were recruited for a cross-sectional survey at the sexually transmitted infections clinic in Amsterdam, the Netherlands, in 2008-2009. Participants completed a questionnaire concerning partnerships in the preceding 6 months. Associations were quantified via multinomial logistic regression models using generalized estimating equations. The outcomes were 'no, or safe anal intercourse', 'insertive UAI', and 'receptive UAI'. We included 5,456 partnerships from 1,890 self-perceived HIV-negative men and 1,861 partnerships from 558 self-perceived HIV-positive men. Within the partnerships, perceived HIV status of the partner was an important determinant of UAI (p < 0.001). Among HIV-negative men, perceived HIV discordance was negatively associated with receptive UAI compared with no or safe UAI (OR 0.57; 95 % CI 0.36-0.92); when the partners were more familiar with each other, the risk of receptive UAI was increased relative to no or safe anal intercourse. Among HIV-positive men, perceived HIV discordance was negatively associated with insertive UAI (OR 0.05; 95 % CI 0.03-0.08). Within partnerships, perceived HIV status of the partner was one of the strongest determinants of UAI among self-perceived HIV-negative and HIV-positive MSM, and discordant serostatus was negatively associated with UAI. The findings suggest that serosorting is one of the main strategies when engaging in UAI.