The Impact of Pre-exposure Prophylaxis for Human Immunodeficiency Virus on Gonorrhea Prevalence

Australian Sexual Health Service Users' Perspectives on Reducing the Oral Transmission of Bacterial STIs: A Qualitative Study

Growing rates of bacterial sexually transmitted infections (STIs) demand new approaches to STI prevention. Sexual practices involving saliva or direct contact with the mouth increase the risk of STI transmission, but community awareness remains largely unexplored in the literature. The Community Awareness and Surveillance of STI Transmission study sought to explore sexual health clinic attendees' awareness of oral STIs; experiences when seeking testing and treatment; and acceptable educational and clinical interventions. Twenty-one semi-structured interviews were conducted with a diverse group of Melbourne Sexual Health Center attendees'. Reflective thematic analysis was undertaken, revealing key themes across people of different genders, sexual identities, ages, and nationalities. All participants emphasized the importance of understanding how their sexual practices might put them at risk of an oral STI. They also sought care from specialist sexual health services with the expectation that health-care providers (HCPs) in these settings had more understanding of diverse sexual practices. Participants' decisions to protect themselves against oral STIs were primarily driven by the effect the decision had on pleasure and intimacy. Comfort during the health-care encounter and trust in HCPs facilitated better understanding of individual STI risk. Differences in awareness and risk reduction strategies were noted based on past experience with oral testing and STIs. These findings highlight the importance of HCPs and public health interventions providing solutions that recognize the central role of pleasure and intimacy in our sexual lives.

Infectious Disease Modelling of HIV Prevention Interventions: A Systematic Review and Narrative Synthesis of Compartmental Models

BACKGROUND

The HIV epidemic remains a major public health problem. Critical to transmission control are HIV prevention strategies with new interventions continuing to be developed. Mathematical models are important for understanding the potential impact of these interventions and supporting policy decisions. This systematic review aims to answer the following question: when a new HIV prevention intervention is being considered or designed, what information regarding it is necessary to include in a compartmental model to provide useful insights to policy makers? The primary objective of this review is therefore to assess suitability of current compartmental HIV prevention models for informing policy development.

METHODS

Articles published in EMBASE, Medline, Econlit, and Global Health were screened. Included studies were identified using permutations of (i) HIV, (ii) pre-exposure prophylaxis (PrEP), circumcision (both voluntary male circumcision [VMMC] and early-infant male circumcision [EIMC]), and vaccination, and (iii) modelling. Data extraction focused on study design, model structure, and intervention incorporation into models. Article quality was assessed using the TRACE (TRAnsparent and Comprehensive Ecological modelling documentation) criteria for mathematical models.

RESULTS

Of 837 articles screened, 48 articles were included in the review, with 32 unique mathematical models identified. The substantial majority of studies included PrEP (83%), whilst fewer modelled circumcision (54%), and only a few focussed on vaccination (10%). Data evaluation, implementation verification, and model output corroboration were identified as areas of poorer model quality. Parameters commonly included in the mathematical models were intervention uptake and effectiveness, with additional intervention-specific common parameters identified. We identified key modelling gaps; critically, models insufficiently incorporate multiple interventions acting simultaneously. Additionally, population subgroups were generally poorly represented-with future models requiring improved incorporation of ethnicity and sexual risk group stratification-and many models contained inappropriate data in parameterisation which will affect output accuracy.

CONCLUSIONS

This review identified gaps in compartmental models to date and suggests areas of improvement for models focusing on new prevention interventions. Resolution of such gaps within future models will ensure greater robustness and transparency, and enable more accurate assessment of the impact that new interventions may have, thereby providing more meaningful guidance to policy makers.

Determining the screening frequency for sexually transmitted infections for people who use HIV pre-exposure prophylaxis: a systematic review and meta-analysis

OBJECTIVES

Although the World Health Organization recommends 'frequent' screening of sexually transmitted infections (STI) for people who use pre-exposure prophylaxis for HIV, there is no evidence for optimal frequency.

METHODS

We searched five databases and used random-effects meta-analysis to calculate pooled estimates of STI test positivity. We narratively synthesized data on secondary outcomes, including adherence to recommended STI screening frequency and changes in STI epidemiology.

RESULTS

Of 7477 studies, we included 38 for the meta-analysis and 11 for secondary outcomes. With 2-3 monthly STI screening, the pooled positivity was 0.20 (95% confidence interval [CI]: 0.15-0.25) for chlamydia, 0.17 (95% CI: 0.12-0.22) for gonorrhea, and 0.07 (95% CI: 0.05-0.08) for syphilis. For chlamydia and gonorrhea, the positivity was approximately 50% and 75% lower, respectively, in studies that screened 4-6 monthly vs 2-3 monthly. There was no significant difference in the positivity for syphilis in studies that screened 4-6 monthly compared to 2-3 monthly. Adherence of clients to recommended screening frequency varied significantly (39-94%) depending on population and country. Modeling studies suggest more frequent STI screening could reduce incidence.

CONCLUSION

Although more frequent STI screening could reduce delayed diagnoses and incidence, there remain significant knowledge gaps regarding the optimal STI screening frequency.

Real-world trends in incidence of bacterial sexually transmissible infections among gay and bisexual men using HIV pre-exposure prophylaxis (PrEP) in Australia following nationwide PrEP implementation: an analysis of sentinel surveillance data

BACKGROUND

Although data from large implementation trials suggest that sexually transmissible infection (STI) risk increases among gay and bisexual men who initiate HIV pre-exposure prophylaxis (PrEP), there are few data on the trends in population-level STI incidence in the years following widespread PrEP implementation. We aimed to describe trends in bacterial STI incidence among gay and bisexual men using PrEP across Australia in the context of broad PrEP availability through Australia's subsidised medicines scheme.

METHODS

We analysed linked clinical data from HIV-negative gay and bisexual men aged 16 years or older who had been prescribed PrEP across a sentinel surveillance clinical network, including 37 clinics in Australia, between Jan 1, 2016, and Dec 31, 2019. Patients were included if they had STI testing at least twice during the observation period. Repeat testing methods were used to calculate chlamydia, gonorrhoea, syphilis, and any STI incidence rates during individuals' periods of PrEP use. Incidence rate ratios (IRRs) for estimated change in incidence per half calendar year (6-month) period were calculated using negative binomial regression. Secondary analyses compared STI incidence rates across individuals initiating PrEP in each year from 2016 to 2019, as well as by length of time using PrEP (per each additional 6 months of PrEP use).

FINDINGS

22 730 men were included in the analyses. During the observation period, 11 351 chlamydia infections were diagnosed in 6630 (30·1%) of 22 034 men over 25 991·2 person-years of PrEP use (incidence rate 43·7 cases [95% CI 42·9-44·5] per 100 person-years). Chlamydia incidence decreased from 48·7 cases per 100 person-years in July-December, 2016, to 42·0 cases per 100 person-years in July-December, 2019 (IRR for estimated change per 6-month period 0·98 [95% CI 0·97-0·99]; p=0·0031). 9391 gonorrhoea infections were diagnosed in 5885 (26·9%) of 21 845 men over 24 858·7 person-years of PrEP use (incidence rate 37·8 cases [95% CI 37·0-38·5] per 100 person-years). Gonorrhoea incidence decreased from 45·5 cases per 100 person-years in July-December, 2016, to 37·2 cases per 100 person-years in July-December, 2019 (IRR 0·97 [95% CI 0·96-0·98]; p<0·0001). Declines in chlamydia and gonorrhoea incidence were most prominent in the first 18 months of observation and incidence was stable thereafter. 2062 syphilis infections were diagnosed in 1488 (7·7%) of 19 262 men over 21 978·9 person-years of PrEP use (incidence rate 9·4 cases [95% CI 9·0-9·8] per 100 person-years). Syphilis incidence increased from 6·2 cases per 100 person-years in July-December, 2016, to 9·8 cases per 100 person-years in July-December, 2019 (IRR 1·08 [95% CI 1·05-1·10]; p<0·0001).

INTERPRETATION

Chlamydia and gonorrhoea incidence among gay and bisexual men using PrEP were highest in the early months of PrEP implementation in Australia and stabilised at slightly lower rates thereafter following wider PrEP uptake. Lower prospective STI risk among people initiating PrEP in later years contributed to the observed trends in STI incidence. Widespread PrEP implementation can contribute to increased STI screening and detection.

FUNDING

Australian Department of Health, National Health and Medical Research Council.