Amy Matser

Background: The uptake of preexposure prophylaxis (PrEP) against HIV is low among young men who have sex with men (MSM) in the Netherlands. Studying the intention to use PrEP among non-PrEP using young and older MSM can guide health authorities in developing new prevention campaigns to optimize PrEP uptake. Methods: We investigated the sociodemographic, behavioral, and psychosocial factors associated with a high PrEP use intention in the coming 6 months among 93 young MSM (aged ≤25 years), participating in an online survey, and 290 older MSM (aged ≥26 years), participating in an open, prospective cohort in 2019 to 2020. Results: Perceiving PrEP as an important prevention tool was associated with a high PrEP use intention among young and older MSM. Among young MSM, a high level of PrEP knowledge and believing that PrEP users take good care of themselves and others were associated with a high PrEP use intention. Among older MSM, 2 or more anal sex partners, chemsex, high HIV risk perception, and believing PrEP increases sexual pleasure were associated with a high PrEP use intention. Believing PrEP leads to adverse effects was associated with a low intention to use PrEP among older MSM. Conclusions: To conclude, we showed that both behavioral and psychosocial factors were associated with a high PrEP use intention among young and older MSM. In addition to focusing on sexual behavior and HIV risk, future prevention campaigns and counseling on PrEP could incorporate education, endorsing positive beliefs, and disarming negative beliefs to improve the uptake of PrEP in young and older MSM.

Objective: To investigate the impact of Dutch COVID-19 restrictions on sexual behavior and HIV/sexually transmitted infection (STI) acquisition among men who have sex with men (MSM) participating in the Amsterdam Cohort Studies (ACS) on HIV in Amsterdam. Methods: ACS participants complete a questionnaire on sexual behavior and are tested for HIV/STI biannually. They may also be tested at the STI clinic in-between study visits. On May 29, 2020, ACS participants were invited to complete an online questionnaire on health, COVID-19 risk perceptions, and sexual behavior. Determinants of reporting casual sex partners (CSP) during COVID-19 restrictions were examined using logistic regression. Results: Of 683 MSM, 353 (52%; median age, 47 years; interquartile range, 38–53 years) completed the questionnaire. Since COVID-19, 73% reported a reduction in the number of CSP. CSP during COVID-19 restrictions were reported by 133 MSM (38%) and, in multivariable analysis, was associated with not having a college/university degree, being single, lower perceived importance of avoiding COVID-19, number of CSP before COVID-19, and current preexposure prophylaxis use (P < 0.05 for all). During COVID-19 restrictions, no HIV infections were diagnosed, and the STI positivity rate was 8%. Conclusion: Since COVID-19, the number of CSP decreased among MSM, and there may have been a temporary reduction in HIV/STI transmission. Some MSM were not fully compliant to social distancing regulations and reported CSP, which was related to prior sexual behavior and low perceived importance of avoiding COVID-19. For these men, it is important to maintain accessible HIV/STI-related testing and care during times of lockdown.

Background: Before 2019, availability of affordable HIV preexposure prophylaxis (PrEP) was limited in the Netherlands. Consequently, some men who have sex with men and transgender persons obtained PrEP informally, that is, without a prescription. Methods: Between September 2017 and August 2018, we enrolled informal PrEP users in a cohort study (Informal PrEP [InPrEP]) at the Amsterdam Sexually Transmitted Infections (STI) Clinic. We compared PrEP use, PrEP eligibility and intention, chemsex, and STI positivity between 3 groups: (1) informal PrEP users enrolled in InPrEP, (2) nonenrolled informal PrEP users, and (3) non-PrEP users. Also, we assessed intention and associated characteristics among non-PrEP users who were eligible for PrEP. Results: During the study period, we enrolled 118 informal PrEP users in InPrEP who were compared with 224 nonenrolled informal PrEP users and 4975 non-PrEP users. Preexposure prophylaxis eligibility rates were 83.1%, 93.4%, and 63.0%; chemsex were reported by 39.1%, 48.1%, and 11.7%; and STI positivity was reported by 28.0%, 42.5%, and 20.3%, respectively. Among PrEP-eligible non-PrEP users, PrEP intention was 16.6% and associated with increasing age, non-Dutch origin, higher educational level, receptive condomless anal sex, increasing number of sex partners, chemsex, and sex with men only. Conclusions: Most informal PrEP users are eligible to use PrEP and have a clear sexual health care need. Especially in settings with limited PrEP access, providing the necessary care for informal PrEP users is important. The intention to use PrEP is low among PrEP-eligible STI clinic visitors. Further research should investigate modes to increase PrEP intention among PrEP-eligible persons.

In the current COVID-19 pandemic a key unsolved question is the duration of acquired immunity in recovered individuals. The recent emergence of SARS-CoV-2 precludes a direct study on this virus, but the four seasonal human coronaviruses may reveal common characteristics applicable to all human coronaviruses. We monitored healthy subjects over a time span of 35 years (1985-2020), providing a total of 2473 follow up person-months, and determined a) the time to reinfection by the same seasonal coronavirus and b) the dynamics of coronavirus antibody depletion post-infection. An alarmingly short duration of protective immunity to coronaviruses was found. Reinfections occurred frequently at 12 months post-infection and there was for each virus a substantial reduction in antibody levels as soon as 6 months post-infection.

Background and Aims: Men who have sex with men (MSM) are at high risk for both drug use and sexually transmitted infections (STI). We aimed to (1) identify subgroups of drug use during sex among MSM in Amsterdam and after classifying participants and (2) compare sexual behaviour and STI across groups.Design: Cross‐sectional study. Latent class analysis was used to identify subgroups with similar drug use patterns, between which sexual behaviour and STI prevalence were compared.Setting: Four different studies conducted at the STI out‐patient clinic in Amsterdam, the Netherlands, between January 2014 and June 2016.Participants: A total of 1130 self‐declared MSM, aged ≥ 18 years.Measurements: Self‐reported drug use, laboratory‐confirmed STI, socio‐demographics, sexual behaviour (including number of partners), condom use.Findings: Median age was 40 years [interquartile range (IQR) = 32–47]. We identified five latent classes of users, which we labelled: ‘no substance’ (n = 162), ‘alcohol’ (n = 159), ‘nitrites and erectile dysfunction drugs (EDD)’ (n = 286), ‘polydrug’ (n = 257) and ‘chems’ (n = 266). Median number of sex partners significantly differed across classes (P < 0.001), ranging from two (IQR = 1–6) in the ‘no substance’ class to 20 (IQR = 10–45) in the ‘chems’ class. The proportion of MSM reporting condomless anal sex also differed across classes (P < 0.001), ranging from 45.6% in the ‘no substance’ class to 86.5% in the ‘chems’ class. Compared with the ‘no substance’ class, the odds of STI were 3.9‐fold [95% confidence interval (CI) = 1.1–14.4] higher in the ‘alcohol’ class, 8.9‐fold (95% CI = 2.7–29.2) higher in the ‘nitrites and EDD’ class, 12.8‐fold (95% CI = 3.9–41.9) higher in the ‘polydrug’ class and 15.0‐fold (95% CI = 4.6–48.8) higher in the ‘chems’ class.Conclusion: There are five distinct classes of drug use in a sexual context among men who have sex with men in Amsterdam, the Netherlands. Classes with higher levels of drug use appear to coincide with higher levels of sexual risk behaviour and sexually transmitted infections.

Over-the-counter intra-vaginal lactic-acid containing douches are marketed as vaginal hygiene products that support optimal vaginal pH balance. We report the effect of a commercially available douche (Etos®) on the vaginal microbiota (VM) in a prospective study. Twenty-five healthy women were recruited through advertisements in 2015–2017 (ethical approval: METC-2014_413) and followed over three menstrual cycles. The participants had a median age of 24 years [IQR: 22–29], were mostly Dutch-Caucasian (88%), and 60% used combined oral contraceptives. All participants douched three times a week during the second cycle, starting on the first day of that cycle. Participants completed a questionnaire at baseline, kept a daily diary to report douching, menses, and sexual activity, self-collected vaginal swabs every other day during the first and third cycle and daily during the second cycle, and measured vaginal pH mid-cycle. A median of 44 vaginal swabs [inter-quartile range (IQR): 41–50] were assessed per participant by 16S rRNA gene (V3-V4 region) sequencing and a Candida albicans PCR was done at four time-points. At baseline, 21 participants (84%) had Lactobacillus-dominated VM (Lactobacillus crispatus (n = 14), L. iners (n = 6), or diverse Lactobacillus species (n = 1) and 4 participants (16%) had VM consisting of diverse anaerobes. In multinomial logistic regression models, a trend towards increased odds were observed for having diverse anaerobic VM in the second and third cycle, compared to the first cycle, after adjusting for menses [odds ratio (OR) = 1.4 (95% CI: 0.9–2.1) and OR = 1.7 (95% CI: 0.9–3.1), respectively] (p = 0.376). Douching did not affect vaginal pH. Menses increased the odds for having VM consisting of diverse anaerobes almost two-fold (OR = 1.7; 95% CI: 1.0–2.8), while douching during menses increased the odds 2.6 fold (OR = 2.6; 95% CI: 1.0–6.5), compared to not menstruating (p = 0.099). Participants were more likely to test positive for C. albicans after cycle 2, compared to cycle 1 [OR = 3.0 (95% CI: 1.2–7.2); p = 0.017]. The Etos® douche did not significantly affect the vaginal pH or VM composition, although increased odds for having diverse anaerobic VM was observed, especially when douching during menses. Furthermore, douching may promote C. albicans infections.

HIV and other sexually transmitted infections remain a burden on men who have sex with men in the era of effective combination antiretroviral therapy. New prevention efforts are therefore needed. One of these approaches is the current country-wide free condom distribution at gay bars with darkrooms and gay saunas in the Netherlands. This study assessed the effects of free condom distribution on incidence and burden of disease of HIV and other sexually transmitted infections. A static model was constructed to calculate the impact of free condom distribution on HIV, hepatitis C, chlamydia, gonorrhoea, and syphilis among men who have sex with men visiting these venues. Outcomes included new infections averted and disability-adjusted life years averted. Scenario studies were performed to predict the effects of a further increase of condom use, condom effectiveness and coverage. Lastly, cost-effectiveness and sensitivity analyses were performed. Our model showed that condom use at public sex venues increased after the intervention. Annual incidence risk decreased, ranging from 5.73% for gonorrhoea to 7.62% for HIV. The annual number of new infections averted was largest for chlamydia and gonorrhoea (261 and 394 infections, respectively), but 42 new HIV infections were averted as well. In scenarios where condom use and condom effectiveness were further increased, the number of infections reduced more extensively. Over 99% of the decrease in burden of disease was due to HIV. The intervention was cost-effective and cost-saving (for every €1 spent on condom distribution, €5.51 was saved) and remained this in all sensitivity analyses. Free condoms at public sex venues could reduce the transmission of HIV and other sexually transmitted infections. Condom distribution is an affordable and easily implemented intervention that could reduce the burden of disease in men who have sex with men substantially.

In the Netherlands, there are strong disparities in Chlamydia trachomatis (CT) prevalence between ethnic groups. The current study aims to identify whether socioeconomic status, sexual risk behavior and sexual healthcare seeking behavior may explain differences in CT seroprevalence between ethnic groups. We used 2011–2014 baseline data of the HELIUS (HEalthy LIfe in an Urban Setting) study, a multi-ethnic population-based cohort study in Amsterdam, the Netherlands, including participants from Dutch, African Surinamese, South-Asian Surinamese, Ghanaian, Moroccan and Turkish origin. For this analysis, we selected sexually active, heterosexual participants aged 18–34 years old. CT seroprevalence was determined using a multiplex serology assay. The CT seroprevalence ratios between different ethnicities are calculated and adjusted for potential indicators of socioeconomic status, sexual risk behavior and sexual healthcare seeking behavior. The study population consisted of 2001 individuals (52.8% female) with a median age of 28 years (IQR 24–31). CT seropositivity differed by ethnicities and ranged from 71.6% (African Surinamese), and 67.9% (Ghanaian) to 31.1% (Turkish). The CT seroprevalence ratio of African Surinamese was 1.72 (95% CI 1.43–2.06) and 1.52 (95% CI 1.16–1.99) of Ghanaian as compared to the Dutch reference group, after adjustment for socioeconomic status, sexual risk behavior and sexual healthcare seeking behavior. Indicators of socioeconomic status, sexual risk behavior, and sexual health seeking behavior could not explain the higher CT seroprevalence among African Surinamese and Ghanaian residents of Amsterdam.